Turmeric and Black Pepper: A Winning Combination

Turmeric (Curcuma longa) is a spice held in high regard for its bountiful health properties and its culinary uses. It’s a favorite herb of Ayurvedic and Chinese traditional medicine, and its therapeutic uses date back thousands of years. Numerous studies have found that turmeric root can have a significant positive effect on neurological, cardiovascular, metabolic, immune system, and cellular health. It may even help support your thyroid and promote longevity. Turmeric owes its many health-promoting qualities to curcumin, the natural compound that gives turmeric its rich golden color.

The Trouble With Turmeric

For all its miraculous health benefits, turmeric does have one weakness. The golden spice has very low bioavailability. This means that your body can only use a very small portion of the turmeric you consume. As the absorption levels of curcumin are very low, your body cannot harness the full healing properties of the spice. Fortunately, there is a simple way to enhance bioavailability. Just add black pepper to unlock the full potential of turmeric.

Black Pepper Can Boost Bioavailability by 2000%

Black pepper (Piper nigrum) is one of the most commonly consumed spices on the planet. In many parts of the world, you can find it on nearly every dinner table, right next to the salt. It’s usually just called “pepper,” but it also bears the nicknames “black gold” and “the king of spices.” It has a phenomenally long shelf life. Properly stored, black pepper can maintain its taste and aroma for many years.

Black pepper also has many health benefits of its own. It’s been used to relieve nausea, headaches, poor digestion, and sore throats. Much like how turmeric owes its healthy properties to curcumin, black pepper gets both its health benefits and its pungent flavor from a natural alkaloid compound called piperine.

Taking turmeric with black pepper may boost its bioavailability up to an astonishing 2000%. This is because piperine acts as an excellent bio-enhancer. Put simply, it can improve the bioavailability of other substances in the body.[1] The serving needed is quite small. You only need a pinch of pepper to enhance the absorption of turmeric.

The Powerful Potential of Piperine

When you consume a nutrient, your digestive system can only absorb a certain portion of it. The proportion of a nutrient that your body can digest, absorb, and utilize is its bioavailability. For example, the bioavailability of protein is very high. Most people use over 90% of the protein they consume. After it moves through your digestive system, your body eliminates the rest as waste.

For a nutrient to be absorbed into your body, it must pass through a membrane in your gut into your bloodstream. Large molecules have a more difficult time getting through this barrier. Piperine may help relax your intestinal membrane, allowing larger particles, like turmeric, to pass through.

The effect of piperine on the liver may play another factor. As part of your normal metabolism, your liver releases a substance called UDP-glucuronic acid. In a process called glucuronidation, this acid bonds with other substances to make them more water-soluble, and thus more easily excreted.

With turmeric, this glucuronidation may operate too quickly, eliminating the herb from your system before your body can make full use of it. Studies have found that piperine lowers the blood levels of UDP-glucuronic acid, inhibiting glucuronidation. In other words, it slows your liver metabolism of curcumin enough that your body can absorb the nutrient more effectively.

The Perks of Turmeric Plus Pepper

While turmeric and black pepper each have their own unique health properties, many of the properties are enhanced when you combine the two.

Possesses Antioxidant Properties

Turmeric contains many compounds with antioxidant properties. Curcumin, in particular, is a potent antioxidant. In fact, it’s ten times more powerful than resveratrol, the much-hyped antioxidant in red wine.

Piperine possesses its own antioxidant properties. Animal studies have found that piperine can reduce the oxidative stress brought on by a high-fat diet. By consuming pepper with turmeric regularly, you get double the antioxidant protection, helping you stay healthier, longer.

Resists Harmful Organisms

In vitro studies have found that turmeric resists harmful organisms, though more research is required to determine if this effect can be replicated in the human body. As a bioenhancer, black pepper not only boosts these abilities, it resists harmful organisms as well.

Protects Liver Health

In the liver, turmeric helps increase cholesterol elimination by boosting bile production. Curcumin also protects liver cells from damage caused by toxins such as peroxide, galactosamine, tobacco smoke, and household chemicals. Black pepper helps by boosting the bioavailability of glutathione, an important compound that protects the liver on a cellular level.

Eases Discomfort

Both turmeric and black pepper work to relieve temporary discomfort. Piperine desensitizes a pain receptor called TRPV1. Turmeric helps ease occasional joint discomfort. Put them together and you have surefire relief for stiffness and soreness. This is one of the reasons turmeric is so popular among athletes.

Aids Digestion

Ayurvedic medicine has relied on turmeric to support digestive health for thousands of years. Modern studies have found that it reduces spasms and flatulence. Both turmeric and black pepper have been found to enhance the activity of digestive enzymes in the gut, helping your system process food more quickly and easily.

The Best Ways to Get Black Pepper With Turmeric

Whole foods are always the best way to consume nutrients. When combining turmeric and black pepper, look to food sources such as curry. It may be a happy accident, or maybe the ancient peoples of India knew something we didn’t, but many recipes for curry happen to include turmeric and black pepper. You can also make a tasty tea from turmeric, black pepper, and other healing herbs like capsaicin. Simply mix these herbs into a high-fat liquid like almond milk and enjoy.

While undoubtedly delicious, making curry every day could prove inconvenient. In these cases, you should consider a turmeric and black pepper supplement. Read the label carefully as many turmeric extracts neglect to include black pepper. You could add your own, but top quality blends will already include both. Global Healing Center’s Turmeric extract combines these wonderful spices into one convenient, potent, and highly bioavailable blend.


Is Christmas Tree Syndrome A Real Thing?

As Christmas edges closer, the media is rife with seasonal health stories. But can our Christmas trees really make us sick?
Christmas tree allergy

What is Christmas tree syndrome?

Constantly on the lookout for interesting health stories, I stumbled across a collection of articles about Christmas tree syndrome recently, which piqued my interest.

According to a plethora of news outlets and articles spanning the past decade, Christmas trees are a ready source of mold, which can wreak havoc in our respiratory tract and potentially spoil our holiday fun.

This may be an issue for the roughly 13 percentof the population of the United States who are affected by mold allergy. But the studies cited are far from extensive, and mold allergy is not terribly well understood.

So, do you need to be throwing doubtful glances at your carefully decorated Christmas conifer, or is the whole thing a holiday hype?

Mold spores, allergy, and asthma

According to the Asthma and Allergy Foundation of America (AAFA), “[I]f, you have an allergy that occurs over several seasons, you may be allergic to the spores of molds or other fungi.”

Spores come in a variety of shapes and sizes, and they are ever-present in our environment — both indoors and outdoors. There may be in excess of 1 million fungal species that inhabit our planet, of which just over 100 families, or genera, can cause mold allergy.

The main culprits, however, are just four: AlternariaCladosporiumPenicillium, and Aspergillus.

Mold spores become dangerous when they reach critical levels. This is the case for individuals who have a mold allergy, as well as those with other allergies or asthma, where mold exposure can serve as a secondary trigger and make symptoms worse.

Our weather and light levels affect the composition and levels of individual spore species, which are in constant flux. Our knowledge of critical spore levels is far from extensive, but studies have suggested that for Alternaria, levels can be as low as 100 spores per cubic meter, while for Cladosporium, it is 3,000 spores per cubic meter.

But what does this have to do with our Christmas trees?

Are Christmas trees a health hazard?

It all started in 1970, when Dr. Derek M. Wyse published a paper titled “Christmas tree allergy: mold and pollen studies” in the Canadian Medical Association Journal.

He found that approximately 7 percent of allergic people saw a spike in symptoms when they had a Christmas tree in their home.

Yet, when he measured the variety of mold spores in 10 festive homes, he found his results largely inconclusive because the type of mold he found in the homes varied. Nonetheless, the term Christmas tree allergy was coined.

Fast forward to 2007, when Dr. Phillip Hemmers reported at the annual meeting of the American College of Allergy, Asthma & Immunology in Dallas, TX, that he had followed the fate of one particular Christmas tree.

He found that mold spores had gone up by more than fivefold during a 14-day period over the holidays, reaching 5,000 spores per cubic meter at the end of the festive period.

In 2011, Dr. Lawrence E. Kurlandsky — along with his colleagues from the State University of New York Upstate Medical University in Syracuse — published a more extensive study.

Having analyzed clippings from 28 Christmas trees belonging to their team and fellow staff, they found 53 mold species, of which 70 percent were potentially harmful.

Christmas trees — yay or nay?

Winter sees an annual peak in colds, flu outbreaks, and asthma attacks. The exact reasons aren’t known. But whether your Christmas tree or a combination of other factors is really to blame is difficult to say.

However, if you do have allergies or asthma, it’s worth taking the potential spike in tree-related spore levels seriously. Dr. Kurlandsky recommends washing your tree before bringing it inside, keeping it only for the minimum time possible, and using an air purifier to keep spore levels in check.

The AAFA recommend keeping your living spaces clear of other sources of mold and reducing damp by lowering humidity levels.

For those not affected by allergies, however, the alarm bells are off. “If you and your children don’t have any obvious allergies, then it is probably not going to bother you,” Dr. Kurlandsky says.

For now, our office Christmas tree is safe after all.

Clinical Efficacy of Hibiscus in Improving Iron Status in Patients with Anemia

Anemia, defined as a hemoglobin (Hb) serum concentration of <11.0 g/dL at sea level, is usually caused by low intake and absorption of dietary iron. Anemia currently affects roughly 67.6% of the population in Africa, many of whom are concurrently exposed to malaria. In Tanzania, hibiscus (Hibiscus sabdariffa, Malvaceae) flower and calyx infusions or juices are among several natural products used for anemia. Hibiscus contains several minerals, including iron, and ascorbic acid, which is known to increase iron absorption. In vivo, an aqueous extract of hibiscus significantly increased hematocrit (Hct) and Hb levels. Clinical trials have evaluated its use in lowering cholesterol, reducing hypertension, and controlling type 2 diabetes; however, none have examined its effect on iron deficiency. Therefore, these authors conducted a randomized clinical trial to measure the effect of hibiscus extract on iron status in patients with anemia.

Hibiscus calyxes were collected from local farms in March 2014, with a voucher specimen deposited in the herbarium of the Botany Department, University of Dar es Salaam, Tanzania. An aqueous extract optimized for both ascorbic acid and iron extraction was prepared to contain 0.831 mg/g L-ascorbic acid and 0.078 mg/g iron. The extract was issued to patients in 10-day dose packs with instructions.

Of the 202 individuals screened, 130 who were eligible (aged 18-50 years, Hb between 8.0-12.9 g/dL for men and 8.0-11.9 g/dL for women [anemic], no use of vitamin or mineral supplements for 30 days before enrollment, no organ impairment, no chronic illness, no blood given or received in prior 6 months, not pregnant or nursing, residents of study area, no history of serious medical conditions, and no participation in any investigational trial for 90 days before the study) were randomly assigned into 4 groups with similar proportions of key characteristics (e.g., gender, age, and Hb levels) in each.

Patients in group D1 (n=35) drank 1 L of the product daily; those in D2 (n=34), 1500 mL; and those in D3(n=32), 2 L. Patients in D4 (control; n=29) took 200 mg ferrous sulphate yielding 65 mg ferrous iron daily. The primary endpoint was changed in iron status indicators (Hb level, serum ferritin [Fer], and Hct parameters [mean corpuscular hemoglobin (MCH), mean corpuscular volume (MCV), and red cell distribution width (RDW)]) between baseline and end of follow-up. Vital signs, laboratory tests, and questionnaires were used at baseline and at clinic visits every 10th day. Tests included complete blood count, renal and liver function tests, and hematology. Adverse events were assessed and classified as mild, medium, or severe. Compliance was monitored through home visits by village health workers in addition to clinic visits.

Patients, from 8 villages in Mkuranga District, Tanzania, had a mean age of 37 ± 11.8 years; 79 (60.8%) were women. About 20% had been ill in the 12 months before baseline, with urinary tract infections most common (41.7%). About 34% were using antibiotics at baseline; 32.7%, analgesics. “A significant proportion” of patients with no reported illness was taking medicine. There were no significant differences among groups in red blood cell characteristics, nutrition, or inflammatory markers at baseline (P>0.05 for all). After 4 weeks, 82 patients remained in the study—18 in group D1, 24 in D2, 21 in D3, and 19 in D4. A total of 37 were lost to follow-up for unknown reasons; others, for medical reasons or by moving away. Malaria (58 cases) did not cause any cited dropouts. Baseline data on malaria status are not provided.

In this study, the hibiscus treatment was not effective in treating anemia, but showed potential for improving hematological parameters. Fer levels rose significantly in D4 (control; P=0.0014) compared to baseline; in other groups, nonsignificantly (P>0.05). RDW fell, although nonsignificantly, in all groups compared to baseline, most noticeably in D3 (P=0.2754). There was a significant decrease in MCH in D1, D2, and D4 compared to baseline (P<0.05 for all); in D3, there was a nonsignificant decrease in MCH (P=0.0571). In D1 and D4, significant declines in Hb were seen compared to baseline (P=0.0123 and P=0.0219, respectively). [Note: In the article text, the value for D1 is given as P=0.123.]

The authors call for studies with larger populations. Findings differ from a study of hibiscus and pineapple (Ananas comosus, Bromeliaceae) juice, with an average increase in Hb after 9 days that exceeded conventional anemia treatment (+2 g/dL in 3 weeks). Additional studies are also needed to examine the complex comorbidities of anemia and malaria. A recent study in Tanzania found that “iron deficiency appears to protect against both malaria infection and mortality.”1,2


1Richards S. Iron deficiency protective against malaria. The Scientist website. Available at: http://www.the-scientist.com/?articles.view/articleNo/31974/title/Iron-Deficiency-Protective-Against-Malaria/. Published April 13, 2012. Accessed October 4, 2017.

2Gwamaka M, Kurtis JD, Sorensen BE, et al. Iron deficiency protects against severe Plasmodium falciparum malaria and death in young children. Clin Infect Dis. April 15, 2012;54(8):1137-1144.

Peter EL, Rumisha SF, Mashoto KO, Minzi OMS, Mfinanga S. Efficacy of standardized extract of Hibiscus sabdariffa L. (Malvaceae) in improving the iron status of adults in malaria endemic area: a randomized controlled trial. J Ethnopharmacol. September 14, 2017;209:288-293.

What Do You Know About Rose Water?

Rose water is a liquid made from water and rose petals. It is used as a perfume due to its sweet scent, but it has medicinal and culinary values, as well.

There is a long tradition of rose water being used in medicine, including in Iran and other parts of the Middle East, as far back as the 7th century.

There is also evidence of North American Indian tribes using it to treat ailments.

Fast facts on rose water:

  • Rose water can usually be used without any side effects.
  • Rose water contains numerous, powerful antioxidants.
  • Recent research has found that it can help relax the central nervous system.

What are the benefits?

Below, we look at some of the benefits of rose water and their uses in medicine.


Rose water in small glass bottle, next to rose flower.

Rose water is often used as a perfume, though it also has many medicinal benefits.

The skin is the largest organ in the body and acts as a barrier against UV radiation, chemicals, and other physical pollutants.

The antioxidants in rose water protect the cells in the skin against damage.

Rose water also has anti-inflammatory properties, which means it can be put on the skin to soothe the irritation caused by conditions, such as eczema and rosacea.

Rose water acts as an inhibitor against elastase and collagenase, which are both harmful to the skin.

This, in turn, can help soothe the skin and reduce redness, as well as act as an anti-aging product by reducing the appearance of lines and wrinkles.


Due to its soothing and anti-inflammatory effect, rose water can be taken to treat a sore throat. Furthermore, a study has shown that it can act as a relaxant on the muscles in the throat.


In its liquid form rose water can be used as part of an eye drop and has been shown to have excellent benefits for people with eye problems.

Conditions it can help treat include:

  • conjunctivitis
  • conjunctival xerosis or dry eye
  • acute dacryocystitis
  • degenerative conditions, such as pterygium or pinguecula
  • cataracts


Rose water has antiseptic and antibacterial properties, which mean it can help wounds heal faster, by keeping them clean and fighting injections.

The types of wounds rose water can be used on include:

  • burns
  • cuts
  • scars


Due to its antiseptic properties and the fact rose water can prompt the creation of histamines by the immune system, it has been shown to be useful for preventing and treating infections.


Rose water in a bowl with rose petals, for vapor therapy.

Rose water vapor therapy can improve mood and aid relaxation.

The inhalation of rose water vapors has been traditionally used as a way to improve a person’s mood. The liquid can also be taken orally.

Research has shown that rose water has antidepressant and anti-anxiety properties. It is believed to induce sleep and to have a hypnotic effect similar to that of the pharmaceutical drug diazepam.

It has been used to treat a number of mental health conditions, including:

  • depression
  • grief
  • stress
  • tension

In other medical cases, rose water is known to be beneficial in the treatment of conditions such as dementia and Alzheimer’s disease.

A specific protein fragment called an amyloid, which is created by the body, has been shown to be present in these conditions and to affect the brain function, kill cells, and hinder memory. Encouragingly, properties found in rose water are an inhibitor of this amyloid.


Just as the fumes of rose water are inhaled to help improve mood, it is believed that the de-stressing effects can also help treat headaches and migraines.

Rose water has been used in aromatherapy for some time and can also be applied to a cloth and laid on the forehead for similar effects.


The ingestion of rose water has also been shown to have beneficial effects on the digestive system. It works by increasing bile flow, which helps symptoms of common complaints, including bloating and upset stomach.

The consumption of rose water can also work as a laxative. It can increase both the amount of water in the feces and the frequency of going to the toilet, making it a good treatment for constipation.

What forms and types are there?

Rose water in spray diffuser bottle.

Rose water contains rose oil and tends to be more affordable than pure rose oil.

Rose water contains between 10 and 50 percent rose oil. It is often used in religious ceremonies, as well as in the food industry. However, the same product can come in different forms.

Rose oil

This is created by distilling the rose flower. The oil can be mass-produced in factories and is a pale, yellow color and semisolid.

Due to its high concentration, rose oil is known to be a fairly expensive product.

Dried flowers

Both the buds and the petals of the rose can be dried and are used for different reasons.

Often the petals are eaten, with yogurt, for example, and are used for the previously mentioned digestive benefits.

Other products

Other forms that rose products may come in can include:

  • Rose hips: The seedpods of the roses, which are used either fresh or dried, and as they are or processed in factories.
  • Hydrosol and absolute extract: This can be taken from the flower, petals, or hips and can be a cheaper alternative to rose oil.
  • Ethanolic, aqueous, and chloroform extracts: These can be taken from the flower, petals, or hips and are used for research purposes.

Side effects

A person can apply rose products topically by putting a small amount — about the size of a dime — on their arm as an initial test. If there is no adverse or allergic reaction within 24 hours it can be safely applied elsewhere.

In some cases, a person can have a reaction to rose water due to a particular and often unknown sensitivity to the product.

This can include:

  • burning
  • stinging
  • redness
  • irritation

If someone experiences any of these effects after the use of rose water, they should tell a doctor immediately, as it may be a sign of an infection or allergic reaction.

Our Holiday Favorite Spice: Cinnamon

Most of us think of spices as incidental to our diets, but perhaps it’s time to update our appreciation of these flavorful, and powerfully health-promoting, seasonings.

Spices are defined as any “aromatic vegetable substance.” The keyword is a vegetable. Derived from “vegetables” in the form of tree bark {cinnamon}, seed {nutmeg}, or fruit {peppercorns}, spices have potent anticancer, anti-inflammatory and other health-promoting effects that are daily being confirmed by researchers. Indeed, the following spices have been identified b the National Cancer Institute as having cancer-preventive properties: sage, oregano, thyme, rosemary, fennel, turmeric, caraway, anise, coriander, cumin and tarragon. In one comparison of antioxidant power from the Agricultural Research Center, the compounds of oregano rank higher than vitamin E.

Spices also make major contributions to our health by allowing us to reduce the amounts of salt, sugar and fat in our foods.

We’ve chosen cinnamon as a super-spice because of its general popularity and usefulness.

Cinnamon is welcome all year round, but its special scent is a particular treat in the winter months. What could be more welcome and delicious than a warm mug of apple cider sprinkled with cinnamon or a cinnamon baked apple with crushed nuts on a cold snowy day? It’s exciting to learn that cinnamon has actual health benefits.


Cinnamon, that delightful spice eliciting memories of Grandma’s kitchen and the comforts of home, is actually more than a delicious addition to foods. One of the oldest spices known and long used in traditional medicine, cinnamon is currently being studied for its beneficial effects on a variety of ailments. Recent findings on the power of cinnamon to promote health, in particular, its benefits for people with type ll diabetes, have elevated it to the special status of a super-spice.

cinnamon two types

Cinnamon comes from the interior bark of evergreen trees that are native to Asia. The type we most commonly see in the supermarkets is cassia cinnamon {Cinnamomum cassia}. Known as Chinese cinnamon, it has the sweetly spiced flavor we’re familiar with. Varieties of Chinese cinnamon come from China and northern Vietnam. There’s also Ceylon, or “true,” cinnamon [Cinnamomum zeylanicum}, which is sweeter with a more complex, citrus flavor. Both types of cinnamon are available in sticks {“quills”} or ground.

Cinnamon and your Health:

Today, we’re in the process of learning about the power of cinnamon to affect health, and once you appreciate the special qualities of this mighty spice, I’m sure you’ll be eager to use it more frequently.

Perhaps the most exciting recent discovery concerning cinnamon is its effect on blood glucose levels as well as on triglyceride and cholesterol levels, all which could benefit people suffering from type ll diabetes.

In one study of 60 patients with type ll diabetes, it was found that after only 40 days of taking about one-half teaspoon of cinnamon daily, fasting serum glucose levels were lowered by 18 to 29 percent, triglycerides by 23 to 30 percent, low-density lipoproteins {LDL} by 7 to 27 percent and total cholesterol by 12 to 26 percent. It’s not yet clear whether less than one-half teaspoon a day would be effective. It’s particularly interesting that the effects of the cinnamon lasted for 20 days following the end of the study, leading to speculation that one wouldn’t have to eat cinnamon every day to enjoy its benefits. This is great news for all of us and points out once again the benefits of a varied diet of whole foods and spices. The cinnamon – and perhaps other spices and certainly many foods – that you’re eating today are affecting your health into the future.

Cinnamon, by its insulin-enhancing properties, is not the only spice to show a positive effect on blood glucose levels. Cloves, bay leaves, and turmeric also show beneficial effects.

In addition to being a glucose moderator, cinnamon is recognized as being antibacterial. The essential oils in cinnamon are able to stop the growth of bacteria as well as fungi, including the common yeast CandidaIn one interesting study, a few drops of cinnamon essential oil in about 3 ounces of carrot broth inhibited the growth of bacteria for at least 60 days. By contrast, bacteria flourished in the broth with no cinnamon oil. Cinnamon has also been shown to be effective in fighting the E. coli bacterium.

A recent fascinating study found that just smelling cinnamon increased the subjects’ cognitive ability and actually functioned as a kind of “brain boost.” Future testing will reveal whether this power of cinnamon can be harnessed to prevent cognitive decline or sharpen cognitive performance.

Cinnamon in Your Life:

cinnamon-leafWhat does this exciting news on cinnamon mean to you? While it may not be practical to eat cinnamon on a daily basis, try to incorporate it into dishes when appropriate. If you have been diagnosed with diabetes, make a special effort to increase your cinnamon consumption.

Almost everyone is a fan of cinnamon, but we may need a little inspiration to get cinnamon into our diets more frequently. A dash of cinnamon in applesauce, pumpkin smoothies, and pumpkin pudding, and other foods is a delightful treat.

  • For a healthy dessert, sprinkle cinnamon, a few raisins and walnuts, and a bit of honey, if desired, on a cored apple and bake at 350 degrees for about 45 minutes until soft.
  • Make cinnamon toast. Drizzle some honey and sprinkle some cinnamon on toasted whole grain bread.
  • Simmer, don’t boil, milk with a teaspoon of vanilla and a cinnamon stick for a few minutes. Drink the warm milk with a bit of added honey or pour over hot oatmeal.
  • Combine one teaspoon cinnamon with two tablespoons honey and one cup yogurt. Serve as a dip for sliced fruit or as a dressing for fruit salad. Spoon a dollop on top of hot oatmeal, whole-grain pancakes, waffles or granola.
  • Combine equal parts of cinnamon and cocoa. Sprinkle on yogurt and fruit slices.
  • Combine one tablespoon or more ground cinnamon with one-half cup sesame seeds, one-quarter cup golden flaxseeds and one-quarter cup ground flaxseed meal. Use as a topping on cereal, oatmeal, yogurt, grapefruit halves or cantaloupe. Whole flaxseeds add crunch and fiber, though you get more of the nutritional value from ground flaxseeds.
  • Try to buy organically grown cinnamon, as it is less likely to have been irradiated. We know that irradiating cinnamon may lead to a decrease in its vitamin C and carotenoid content.

Antioxidant Content and Activity of Untreated and Processed Guayusa Tea

Guayusa (Ilex guayusa, Aquifoliaceae) is an evergreen tree native to South America with a long history of use by the indigenous tribes of the Amazon. Traditionally, the twigs and leaves are infused in hot water to create a beverage. A distant relative of yerba maté (I. paraguariensis), this plant is a source of caffeine and is used as a pain reliever. The increasing commercial use of guayusa has led to more interest in its health benefits. The aim of this study was to characterize the phenolic and carotenoid content, as well as the antioxidant activity, of both untreated (green) and processed (blanched or fermented) guayusa.

Guayusa leaves were collected in Pastaza, Ecuador. Both green untreated and processed leaves were provided by the RUNA Foundation (the nonprofit arm of RUNA LLC, a beverage company that processes and sells guayusa; Archidona, Napo, Ecuador). The untreated and processed leaves were freeze-dried and made into separate powders. Blanching and fermentation of guayusa leaves were conducted at the manufacturing plant of the RUNA Foundation, following the standard protocols of the company. The leaf powders were extracted with alcohol-based solvents and assessed for total phenolic content (TPC), phenolic composition, carotenoid composition, and antioxidant capacity by chromatographic or biochemical assay techniques.

A total of 14 phenolic compounds were identified from all sources, nine of which were hydroxycinnamic acids or derivatives (neochlorogenic acid, chlorogenic acid, isochlorogenic acid, five other caffeoyl derivatives, and feruloylquinic acid), and five of which were flavonoids (four quercetin derivatives and one kaempferol derivative). Out of the hydroxycinnamic compounds, chlorogenic acid was the most abundant compound (24.10 mg/g DW [dry weight]). This concentration was similar or higher in comparison to maté and other Ilexspp., but lower than green coffee (Coffea spp., Rubiaceae). In terms of the flavonoids, the flavonol glycoside quercetin-3-O-hexose was the most abundant compound. The flavonol concentration of guayusa (11 mg/g DW) was around two, 20, and 28 times higher than described for yerba maté, other Ilex spp., and tea (Camellia sinensis, Theaceae), respectively.

Industrial processing (blanching or fermentation) did not alter the phenolic profile but did alter phenolic concentrations. As with the unprocessed green leaves, chlorogenic acid was the major phenolic compound found in the blanched samples, while isochlorogenic acid was the most abundant compound in the fermented samples. The TPC of the leaves without industrial processing was 54.86 mg gallic acid equivalents (GAE)/g DW. This is reportedly higher than yerba maté, but lower than green and black tea TPC. Blanching the guayusa leaves resulted in a significant increase in TPC (48.5%, 106.62 ± 4.41; P < 0.05), a concentration that is higher than what has been reported in maté and green and black tea. Fermentation resulted in no significant change in TPC compared to the unprocessed guayusa leaves.

A total of five carotenoid compounds were detected in the green and processed guayusa samples (α- and β-carotene, lutein, and violaxanthin + neoxanthin). In the unprocessed leaves, the concentrations of α-carotene and violaxanthin were higher compared to other teas, but β-carotene and lutein were about the same. There were no significant differences between the total carotenoids of unprocessed and processed leaves, but significantly more total carotenoids were found in the blanched guayusa vs. the fermented guayusa (P < 0.05). Higher contents of β-carotene and lutein were found in the blanched leaves compared to the green untreated leaves (305.39% and 141.52% more, respectively), but there were lower concentrations of α-carotene and violaxanthin + neoxanthin (55.27% and 22.38% less, respectively) (P < 0.05). Fermenting guayusa leaves had no significant effects on the concentrations of β-carotene and lutein. Overall, the results indicated that violaxanthin + neoxanthin was the most easily degraded carotenoid by industrial processing, with 77.6% and 92.5% lost after blanching and fermentation, respectively. Similar effects were seen for other teas.

Guayusa green leaves and blanched leaves had the highest antioxidant activity. The antioxidant activity of the green leaves (2,2-diphenyl-1-picrylhydrazyl [DPPH] assay: 32.98 mM Trolox/100 g DW; oxygen radical absorbance capacity [ORAC] assay: 154.03 mM Trolox/100 g DW) was similar to other studies on this plant species, yerba maté, and tea. The polyphenol and carotenoid content indicated there was a positive and direct correlation with antioxidant capacity, especially with the ORAC assay.

The authors conclude that guayusa has similar antioxidants and activity as yerba maté and tea and that blanching produces the highest concentration of polyphenols, as well as specific carotenoids. It would be interesting if this study also assessed hot water extracts of the tea rather than alcohol extracts since guayusa is often consumed as a hot water infusion. As the authors suggest, more studies are warranted that investigate the content and bioavailability of the bioactive compounds of guayusa to better understand the health benefits of this plant species.


García-Ruiz A, Baenas N, Benítez-González AM, et al. Guayusa (Ilex guayusa L.) new tea: phenolic and carotenoid composition and antioxidant capacity. J Sci Food Agric. September 2017;97(12):3929-3936.

Health Benefits of Moringa

Moringa oleifera is a plant, which is often called the drumstick tree, the miracle tree, the ben oil tree, or the horseradish tree.

Moringa has been used for centuries due to its medicinal properties and health benefits and has antifungal, antiviral, antidepressant, and anti-inflammatory properties.

Facts on Moringa:

  • The tree is native to India but also grows in Asia, Africa, and South America.
  • Moringa contains a variety of proteins, vitamins, and minerals.
  • Moringa oleifera has few known side effects.
  • People taking medication should consult a doctor before taking moringa extract.

What is in Moringa?

Moringa oleifera
Moringa has medicinal properties and contains many healthful compounds.

Moringa contains many healthful compounds such as:

  • vitamin A
  • vitamin B1 (thiamine)
  • B2 (riboflavin)
  • B3 (niacin), B-6
  • folate and ascorbic acid (vitamin C)
  • calcium
  • potassium
  • iron
  • magnesium
  • phosphorus
  • zinc

It is also extremely low in fats and contains no harmful cholesterol.

What are the benefits?

Moringa is believed to have many benefits and its uses range from health and beauty to helping prevent and cure diseases. The benefits of moringa include:

1. Protecting and nourishing skin and hair

Moringa seed oil is beneficial for protecting hair against free radicals and keeps it clean and healthy. Moringa also contains protein, which means it is helpful in protecting skin cells from damage. It also contains hydrating and detoxifying elements, which also boost the skin and hair.

It can be successful in curing skin infections and sores.

2. Treating edema

Edema is a painful condition where fluid builds up in specific tissues in the body. The anti-inflammatory properties of moringa may be effective in preventing edema from developing.

3. Protecting the liver

Moringa appears to protect the liver against damage caused by anti-tubercular drugs and can quicken its repair process.

4. Preventing and treating cancer

Moringa extracts contain properties that might help prevent cancer developing. It also contains niazimicin, which is a compound that suppresses the development of cancer cells.

5. Treating stomach complaints

Moringa extracts might help treat some stomach disorders, such as constipation, gastritis, and ulcerative colitis. The antibiotic and antibacterial properties of moringa may help inhibit the growth of various pathogens, and its high vitamin B content helps with digestion.

6. Fighting against antibacterial diseases

Due to it’s antibacterial, antifungal, and antimicrobial properties, moringa extracts might combat infections caused by SalmonellaRhizopus, and E. coli.

7. Making bones healthier

Moringa also contains calcium and phosphorous, which help keep bones healthy and strong. Along with its anti-inflammatory properties moringa extract might help to treat conditions such as arthritis and may also heal damaged bones.

8. Treating mood disorders

Moringa is thought to be helpful in treating depression, anxiety, and fatigue.

9. Protecting the cardiovascular system

The powerful antioxidants found in Moringa extract might help prevent cardiac damage and has also been shown to maintain a healthy heart.

10. Helping wounds to heal

Extract of moringa has been shown to help wounds close as well as reduce the appearance of scars.

11. Treating diabetes

Moringa helps to reduce the amount of glucose in the blood, as well as sugar and protein in the urine. This improved the hemoglobin levels and overall protein content in those tested.

12. Treating asthma

Moringa may help reduce the severity of some asthma attacks and protect against bronchial constrictions. It has also been shown to assist with better lung function and breathing overall.

13. Protecting against kidney disorders

People may be less likely to develop stones in the kidneys, bladder or uterus if they ingest moringa extract. Moringa contains high levels of antioxidants that might aid toxicity levels in the kidneys.

14. Reducing high blood pressure

Moringa contains isothiocyanate and niaziminin, compounds that help to stop arteries from thickening, which can cause blood pressure to rise.

15. Improving eye health

Moringa contains eyesight-improving properties thanks to its high antioxidant levels. Moringa may stop the dilation of retinal vessels, prevent the thickening of capillary membranes, and inhibit retinal dysfunction.

16. Treating anemia and sickle cell disease

Moringa might help a person’s body absorb more iron, therefore increasing their red blood cell count. It is thought the plant extract is very helpful in treating and preventing anemia and sickle cell disease.

Side effects

Moringa plant dried and powder
Although Moringa may have very few reported side effects, a healthcare professional should be consulted before it is taken.

Anyone considering using moringa is advised to discuss it with a doctor first.

Moringa may possess anti-fertility qualities and is therefore not recommended for pregnant women.

There have been very few side effects reported.

People should always read the label on the extract and follow dosage instructions.

Risks with existing medications

Some of the medications to be particularly aware of are:

  • Levothyroxine: Used to combat thyroid problems. Compounds in the moringa leaf may aid the thyroid function, but people should not take it in combination with other thyroid medication.
  • Any medications that might be broken down by the liver: Moringa extract may decrease how quickly this happens, which could lead to various side effects or complications.
  • Diabetes medications: Diabetes medications are used to lower blood sugar, which moringa also does effectively. It is vital to ensure blood sugar levels do not get too low.
  • High blood pressure medication: Moringa has shown to be effective at lowering blood pressure. Taking moringa alongside other drugs that lower your blood pressure may result in it becoming too low.

Can it aid weight loss?

Evidence has shown that moringa extract can be effective in reducing and controlling weight gain in mice. Its high vitamin B content helps with smooth and efficient digestion and can assist the body when converting food into energy, as opposed to storing it as fat.

Moringa is thought of:

  • reduce weight gain
  • help to lower cholesterol and blood pressure
  • prevent inflammation
  • help the body convert fats into energy
  • reduce fatigue and improve energy levels

What are the studies saying?

 Like all supplements, the United States Food & Drug Administration (FDA) does not monitor moringa so there might be concerns about purity or quality. It is essential to understand the validity of the claims made by the manufacturers, whether it is safe to use, and what potential side effects there may be.

There is plenty of recent research to back up the benefits as stated above, though many of the studies are still in the preliminary stages or the tests have only taken place on animals as opposed to humans, so there is plenty more to be done.

American Botanical Council Publishes Online Version of The Identification of Medicinal Plants Book

Online access to identification book provides new quality control resource for herb industry

AUSTIN, Texas (October 19, 2017) — The American Botanical Council (ABC) announces a new benefit for its members around the world: the online publication of The Identification of Medicinal Plants: A Handbook of the Morphology of Botanicals in Commerce, a manual that addresses the macroscopic assessment of 124 medicinal plants used in North America and Europe.

The book was originally co-published in 2006 by ABC with the Missouri Botanical Garden in St. Louis. It was written by Wendy Applequist, PhD, associate curator at the Missouri Botanical Garden’s William L. Brown Center, and illustrated with botanically accurate black-and-white line drawings by artist Barbara Alongi.

Accurate identification of the correct genus and species of botanical raw materials is the first step in quality control of botanical preparations. While several methods of identification are addressed in the introduction — including macroscopic taxonomic identification, microscopy of plant cells, chemical analysis of plant constituents, and molecular analysis of the plant’s DNA — it is Applequist’s opinion that macroscopic analysis of whole plants and plant parts (when possible) is often a preferred method of species identification because it is quick and relatively inexpensive.

The drawings by Alongi emphasize various morphological features of plant parts to aid in the identification process. In some cases (e.g., to estimate the actual size of a plant part, or to illustrate small details), such drawings can be more useful than actual photographs.

“ABC is pleased to be able to make this important book available to its members, particularly those in academic analytical research and in the herb industry,” noted ABC Founder and Executive Director Mark Blumenthal. “Because many botanical raw materials used in the current herb industry are either cut plant parts (e.g., for use as teas) or powders (to be made into capsules or tablets), many companies never receive and process whole plants or whole plant parts. In such cases, microscopy, chemical analysis, and/or genetic (DNA) testing are required analytical methods. But for growers, wildcrafters, collectors, processors, and others who deal with whole plants and their whole parts, this manual is a highly valuable quality control resource.”

Part 1 of the text provides a succinct discussion of the main morphological features of medicinal plants; practical plant identification, including necessary tools and how to deal with dried plant materials; botanical nomenclature and its importance in the identification process; and a description of the format of the botanical entries included in the book.

Part 2 provides a detailed macroscopic description of each of the 124 plants included. Ordered alphabetically by Latin binomial, each entry includes the standardized common name per the American Herbal Products Association’s Herbs of Commerce, 2nd edition, other common names, family, a brief taxonomic representation, plant parts in commerce, a description of the plant and key morphological characteristics, organoleptic characteristics such as taste and odor, information on potential adulteration, references, and botanical illustrations. Each plant entry a downloadable PDF for ease of use.

“Morphological identification of unprocessed botanicals, when it is feasible, is the most rigorous possible form of authentication and the lowest-cost and quickest,” said Applequist. “I hope that ABC’s making this work available online will help to encourage people who work with herbs to develop the skill of old-fashioned botanical identification.”

Stefan Gafner, PhD, ABC’s chief science officer, added: “Macroscopic identification is an essential step in the identification of whole or cut crude herbal materials. Visual inspection not only helps to authenticate the material, but it also enables the detection of excess amounts of foreign matter such as dirt or sand, and improperly handled material that is rotten or filthy. Resources that help with the training and education of analysts in macroscopic analysis are scarce, and, as such, this is a very valuable book and one of the few texts in which information on macroscopic identification of many commercial botanical ingredients is gathered in one place.”

An appendix contains general references, a glossary that defines botanical terms, and illustrations of common leaf and flower characteristics. Finally, an index is included to facilitate easy access to the materials.

The Identification of Medicinal Plants will be available online to ABC members at the Professional level and above effective October 20, 2017. To become an ABC Member or upgrade membership levels, visit ABC’s membership page or call 512-926-4900.

Adulteration of Rhodiola (Rhodiola rosea) Rhizome, Root, and Extracts

By Ezra Bejar, PhD,Roy Upton,b and John H. Cardellina II, PhDc

American Botanical Council, PO Box 144345, Austin, TX 78714
American Herbal Pharmacopoeia, PO Box 66809, Scotts Valley, CA 95067,
cReevesGroup, 1137 Treefern Drive, Virginia Beach, VA 23451*Corresponding author

Keywords: Rhodiola rosea, rhodiola, rhodiola root, rhodiola root extract, arctic root, arctic rose, golden root, adulterant, adulteration, substitution, Rhodiola crenulata, Crassulaceae


Goal: The goal of this bulletin is to provide timely information and/or updates on issues of adulteration, substitution, potential interchangeable use, and mislabeling of Rhodiola rosea rhizome/root, in particular with other species from the genus Rhodiola, e.g., R. crenulata. The bulletin may serve as guidance for quality control personnel, the international herbal products industry, regulators, and extended natural products community in general. It is also intended to summarize the scientific data and analytical methods on the occurrence of species substitution and/or adulteration, the market situation, and economic and safety consequences for the consumer and the industry.

1          General Information 

1.1 Common name for Rhodiola rosea: Rhodiola1

The American Herbal Products Association’s Herbs of Commerce, 2nd edition1 also applies the Standardized Common Name “rhodiola” to R. algida and R. kirilowii. (see section 1.10)


1.2 Other common names:

English: Arctic rose, king’s crown, roseroot, Arctic root, rosewort, snowdown rose, Tibeten rhodiola root1-4

Chinese: Hong jing tian (红景天)1,3,5-8

Danish: Rosenrod

Dutch: Rozewortel

French: Orpin rose, rhodiole, racine arctique, racine d’or

German: Rosenwurz

Italian: Rhodiola, rodiola, radice d’oro, radice ártica

Japanese: Iwa-benkei (イワベンケ)

Mongolian: Yagaan mugez, altan gagnuur9

Norwegian: Rosenrot

RussianRodióla rózovaya (Родиола розовая), zolotoy koren (золотой корень – golden root)

Spanish: Raíz dorada Siberiana, raíz del Ártico, rizoma de Rhodiola

Swedish: Rosenrot

1.3 Accepted Latin binomial: Rhodiola rosea L. 10


1.4 Synonyms: Sedum rhodiola DC., Sedum rosea (L.) Scop., Sedum roseum (L.) Scop. 10

1.5 Common names for Rhodiola crenulata:


English: Bigflower rhodiola root,11 Rhodiola crenulata1


Chinese: Da hua hong jing tian (大花红景天)5-7

1.6 Botanical family: Crassulaceae

1.7 Distribution: Rhodiola rosea is native to boreal areas of Eastern Europe, China, and North America; its range extends from China to Russia, US Northern states, northern Canada, and Alaska. In New England it occurs along the Maine Coast and in southern Vermont. Disjunctive populations extend from the southern Appalachians to North Carolina. Taxonomic lumpers include the genus Rhodiola in a broader concept ofSedum, though most modern floras follow Linnaeus in segregating Rhodiola from Sedum. It is important to be aware that some references to Rhodiola rosea may treat the species as Sedum rosea or Sedum roseum.In the Arctic, plants typically occur in crevices or among patches of moss and other vegetation, often near shores. 9,10 The highest plant densities are found on grassy or rocky slopes on the weather side of coasts (in the north) or mountains (in the south). Depending on the latitude, the plants grow at altitudes from 800–3000 m (2625–9843 ft). In China, Rhodiola rosea grows in the northern to central provinces of Xinjiang, Gansu, Shanxi, Hebei, and Jilin.

Rhodiola crenulata (J.D. Hooker & Thomson) H Ohba is native to the high mountains and plateaus close to the Himalayas of China, Bhutan, Nepal, and the Indian province of Sikkim. In China, R. crenulata is found in the southwestern provinces of Xizang (Tibet), Qinghai, Sichuan, and Yunnan.12,13

1.8 Plant part and form: Rhodiola rosea raw material is sold in the United States in bulk, either in the form of dried rhizome, dried rhizome/root, or standardized extracts of dried rhizome or dried rhizome/root. According to the United States Pharmacopeia (USP), the raw plant material consists of the dried roots and rhizomes of R. rosea L. containing not less than (NLT) 0.3% of the phenylpropanoid glycosides rosarin, rosavin and rosin (these three compounds are also collectively referred to as ‘rosavins’) calculated as rosavin, and NLT 0.08% of salidroside, calculated on a dry weight basis.8 Hydro-alcoholic extracts of R. rosea roots and rhizomes should contain NLT 90.0% and not more than (NMT) 110.0% of the labeled amount of the above-mentioned phenylpropanoid glycosides (rosavins), and NLT 90.0% and NMT 110.0% of the labeled amount of salidroside.7 In Canada, R. rosea is sold as the dried root/rhizome, as an extract (standardized to contain 1-6% rosavins, or 0.8-3% salidroside), or as a tincture.14 Rhodiola rosea is sold in the EU as dried root/rhizome, an herbal tincture or dry extract, (drug:extract ratio 1.5-5:1, extraction solvent 67-70% ethanol, v/v).10

1.9 General use(s): Rhodiola rosea has a long history of use as a medicinal plant, appearing in the body of collected knowledge (materia medica) of many European countries15 and included in several traditional herbal systems in Asia and North America.5,6,14 Between 1748 and 1961, diverse medicinal applications for R. rosea have been reported in the scientific literature of Sweden, Norway, France, Germany, Iceland, and the Soviet Union, principally considered as an adaptogen, or an agent stabilizing physiological processes and promoting homeostasis, with various health-promoting effects.2,15 In Europe it is considered a traditional herbal medicinal product used for temporary relief of stress symptoms, such as fatigue and sensation of weakness.5,16 Uses in the European Union (EU), Australia, and New Zealand include support of cognitive function, such as mental focus and mental stamina, a source of antioxidants, and a source of immune function-enhancing constituents. In North America and Brazil, it is primarily used as an adaptogen, and to improve athletic performance by reducing recovery time after prolonged exercise. 2,14,17-19 In Central Asia, R. rosea was used traditionally as a remedy for the prevention and treatment of cold and flu.2 In Mongolia, R. rosea is traditionally used for fever, lung inflammation, and strengthening of the body, as well as a mouthwash for bad breath. 62

The genus Rhodiola has about 90 species possibly having originated in the mountainous regions of southwest China and the Himalayas. Altogether, over 20 species are used throughout Asia, in some cases interchangeably. Specific uses are given today in traditional Chinese medicine (TCM) to R. crenulata, R. kirilowii, R. quadrifida, R. sacra, and R. yunnanensis; the last four species have been often used as a substitute and even sold as R. crenulata in the Chinese markets.9 Rhodiola crenulata uses include tonification of qi, activation of blood circulation, and unblocking the meridians.11 Other species also mentioned as being used in TCM include R. atuntsuensis, R. algida, R. coccinea, R. himalensis, and R. subopposita. In Tibetan medicine, species such as R. alsia and R. chrysanthemifolia have also been used as a substitute to the more popular R. crenulata.9

According to traditional Chinese medicine expert Subhuti Dharmananda, PhD, of the Institute for Traditional Medicine in Portland, Oregon, the herb entered into some folk applications (local uses, not tied to the theoretical framework of TCM), but it was not an herb commonly recorded in standard Chinese materia medica. Hong jing tian is the Chinese denomination given to the root and rhizome of several Rhodiolaspecies. It is described as an adaptogenic herb that regulates physiological functions, and is believed to have a central stimulant action. Its general tonic actions are similar to those of ginseng (Panax ginseng, Araliaceae) and root and rhizome of Eleutherococcus senticosus (Araliaceae). [email to S. Gafner, May 5, 2017]

1.10 Nomenclature considerations: In the United States, many rhodiola products in the marketplace bear the R. rosea binomial in the nutritional/supplement facts panel listing ingredients on the label. Due to this species-specific statement, any mixing, dilution, substitution, or replacement with other Rhodiolaspecies will lead to a product’s being considered misbranded. Regardless of the law, the interchangeable use of different species within the same genus may create some variations in chemical composition, which could affect quality, safety and efficacy.

The first edition of Herbs of Commerce (1992),20 formerly the basis for standard nomenclature for herbal dietary supplements in the United States and the official document for commercial nomenclature cited in the Code of Federal Regulations (CFR), does not include any Rhodiola species. The second edition of Herbs of Commerce (2000)1 includes R. algida, R. kirilowii, and R. rosea under the standardized common name “rhodiola”, which means these species should be labeled as “rhodiola” or with the correct scientific name. The roots and rhizomes of these species are also assigned the Chinese pinyin name hong jing tian. Rhodiola crenulata is listed separately with the standardized common name of “Rhodiola crenulata” and the Chinese pinyin name da hua hong jing tian. However, the CFR codification was not updated to include this second edition of Herbs of Commerce. In the Pharmacopoeia of the Peoples’ Republic of China (2010 Edition – Part I), the officially accepted species is Rhodiola crenulata and the medicinally used part is the dried root and rhizome. However, the Chinese pharmacopoeia lists hong jing tian rather than da hua hong jing tian as the common name of R. crenulata.

2          Market

2.1 Importance in the trade and market dynamics: The use of R. rosea as an ingredient in dietary supplements is quite extensive. According to the market research company SPINS, sales of R. rosea in the natural channel in the United States have been stable for four consecutive years from 2013-2016 (Table 1). Rhodiola rosea ranked #35 in 2013, and #36 in 2016, with sales in the range of US $2.2-2.5 million in the years 2013-2016. However, in the Mainstream Multi-outlet channel, R. rosea ranked #11 in 2013 with $17.7 million in sales, sliding to #28 in 2016 with $10.1 million in sales. The decrease in the Mainstream Multi-outlet channel is thought to be multifactorial.21

As noted above, the sales data for 2013-2016 (Table 1) indicate a gradual decrease in sales of R. rosea-based products in the United States. Retail pricing for the rhizome is in the range of US $30-100/kg dried rhizome, according to an informal Internet search conducted in September 2016. However, standardized R. rosea extract (3% rosavins/1% salidroside) is sold by suppliers to dietary supplement manufacturers in a price ranging from 80-110 €/kg in the EU and US $70-100/kg, depending on the extract quality. (A. Bily [Naturex] oral communication to E. Bejar, October 5, 2016)

Table 1. Rhodiola Dietary Supplement Sales in the US from 2013-2016

Channel 2013 2014 2015 2016
Rank Sales [US$] Rank Sales [US$] Rank Sales [US$] Rank Sales [US$]
Naturala 35 2,214,255 32 2,561,873 35 2,461,235 36 2,588,730
Mainstream Multi-Outletb 11 17,716,775 17 14,188,978 27 10,624,592 28 10,080,448

aAccording to SPINS (SPINS does not track sales from Whole Foods Market.)
bAccording to SPINS/IRI (The Mainstream Multi-Outlet channel was formerly known as the Food, Drug, and Mass Market channel [FDM], exclusive of possible sales at Walmart, a major retailer in the US and beyond.)
Sources: Smith T, et al.22; T. Smith (American Botanical Council) e-mail to S. Gafner, September 2, 2015 and September 3, 2015. K. Kawa (SPINS) e-mail to S. Gafner, July 11, 2016.

2.2 Supply sources: The largest natural resources for R. rosea are in Russia. The major part of the growing range cannot be exploited due to difficulties in access or sparse populations. Most R. rosea raw material is collected in China by wildcrafters, whose subsistence depends on selling their fresh produce at regional collection sites. Most of the root plant material is gathered in the summertime from a minimum of four-year old plants by digging under the plant, removing most of the rhizome/root and (hopefully) leaving a part of the rhizome/root for the plant to regenerate over the next years. Rhodiola crenulata is often collected for the Chinese market in some regions in China and Mongolia where both species may share ecological niches. Wildcrafters should be able to distinguish R. rosea from R. crenulata easily during the collection season, since R. rosea has yellow flowers with yellow to reddish buds, while R. crenulata flowers are purple.12

The Xinjiang region is one of the most prolific producers of R. rosea with 4-5 collection sites selling about 500 tons of dry rhizomes annually. The dried roots/rhizomes are cleaned, dried, and sold to one of several East China extract manufacturers; most such extracts are sold abroad. Other regions of China, Mongolia, Kazakhstan, Russia, and North America have a more limited supply of R. rosea, and their contribution to the US market is small, except for a few select products. Most Mongolian and Kazakhstani R. rosea end up in the Russian market at a higher price. (A. Bily and C. Pierron [Naturex] oral communication to E. Bejar. September 29, 2016).

Projects for cultivation of R. rosea exist in Denmark, Germany, Canada, Alaska, Bulgaria, Switzerland, and Norway. Production in the latter two countries is small and limited to supply local and regional markets.

2.3 Raw material forms: Dried rhizome/root is sold in whole or powdered form, or after extraction with alcohol-water mixtures and subsequent spray-drying. The extract may contain suitable added substances as carriers. Various lots of extracts are often mixed to meet standardization requirements of the USP monographs.7,8

Because wildcrafters collect the rhizome (with root material) exclusively, and leave parts of the root with the aerial parts of the plant behind to regenerate, it is rare to find adulteration of R. rosea rhizome with aboveground plant parts. However, suppliers from China sell R. rosea aerial plant (herb), flowers, and stems according to their certificates of analysis. The sale of R. rosea herb and flower extracts, correctly labeled as such, is not within the scope of this bulletin.

3          Substitution

3.1 Known substitutes and adulterants: The main concern regarding the authenticity and quality of R. rosea is the admixture of, or substitution with, rhizome/root material from other Rhodiola species. Over 90 Rhodiola species have been documented in the world and in China 73 different Rhodiola species have been reported, mainly in the northwest and southwest regions, such as Tibet and the Sichuan province.19 ManyRhodiola species have similar pinyin names (hong jing tian)23 and are used interchangeably in China and other parts of Asia, including R. crenulata R. heterodontaR. kirilowiiR. quadrifida, and R. semenovii.1,15,19However, R. crenulata is the only species formally accepted in the PPRC.11 Because of the number of imports from Asia, mainly from China, to the United States and to the European herbal supplement industry, R. rosea raw materials are often mixed or interchanged with other Asian species, including R. crenulata, but also other Rhodiola species.19,23 Adulteration with materials other than those from the Rhodiola genus, e.g., with 5-hydroxytryptophan, has been described by Booker et al.,19 but seems to be infrequent.

Herbal medicine experts have expressed contrasting views about the interchangeable use of R. rosea and other Rhodiola species in standard-setting documents and reference textbooks. The European Medicines Agency’s community herbal monograph specifies the use of R. rosea for rhodiola-containing products that are marketed as an herbal drug for temporary relief of symptoms of stress.4,5  Similarly, the highly regarded German textbook Wichtl – Teedrogen und Phytopharmaka24 indicates that rhizomes from other Rhodiola species may appear as adulterants of R. rosea. However, the USP Herbal Medicines Compendiumlists R. crenulata, R. kirilowii, R. sacra, R. sachalinensis, and R. yunnanensis, as confounding materials for R. rosea rhizome.8 This is a more accurate way to characterize the substitution or admixing of related species within a genus. In the United States, by regulatory definition, replacement by, or admixing with a species that is listed under the same common name in the American Herbal Products Association’s Herbs of Commerce, 1st edition,20 is considered substitution, unless the product label notes a particular species in the ”active ingredients” section. Hence, products labeled to contain “rhodiola”, but not specifying a particular species of Rhodiola, may be derived from a number of Rhodiola species (see section 1.1).

3.2 Sources of information supporting substitution of rhodiola and frequency of occurrence: With the use of a rapid resolution liquid chromatography (RRLC, a variation of high-performance liquid chromatography [HPLC]) method, Ma et al. found that approximately one-third of the commercial rhodiola rhizome powder extract samples they tested did not show a consistent RRLC profile and lacked the characteristic peaks of rosarin, rosavin, and rosin present in authentic R. rosea rhizome.25 However, absence of rosavins may not always be indicative of adulteration. If not handled properly, rosavins may be subject to enzymatic degradation and thus not be present in a finished product (Y-C Ma email to S. Gafner, May 26, 2017).

Booker et al. analyzed 39 raw materials of products from different vendors in the United Kingdom (UK) labeled as R. rosea. Most products were sold without any registration (i.e., generally unlicensed food supplements available on the internet or from retail outlets), although the researchers included two Traditional Herbal Medicine products registered under the traditional herbal medicine products directive (THMPD).19 Registration of a product under the THMPD requires the submission of appropriate data supporting the safety of the product (qualitative and quantitative composition, manufacturing process and controls, potential risks to the environment, therapeutic benefits and dosage, contraindications and known adverse reactions, pharmacovigilance data, and packaging information), but does not include the need for preclinical or clinical data. Products were compared to R. rosea crude drug reference material and two bulk powders. The samples were analyzed by 1H-NMR (nuclear magnetic resonance) spectroscopy and high-performance thin-layer chromatography (HPTLC). Results from 1H-NMR were evaluated statistically using principal component analysis (PCA). Rhodiola rosea products registered under the THMPD were confirmed to contain authentic R. rosea, but seven (about 25%) unregistered food supplements labeled as R. roseaproducts were determined to be substituted with various other Rhodiola species, and in one instance adulterated with synthetic 5-hydroxytryptophan (5-HTP). The PCA model used to analyze 1H NMR spectroscopy data appeared to discriminate poorly between dietary supplement products containing R. rosea extracts and those extracts containing R. crenulata or other Rhodiola species when using the entire NMR spectrum, likely due to the presence of excipients. Restricting the 1H NMR spectrum to the aromatic region allowed the distinction among R. rosea and various other Rhodiola species. The HPTLC method detected both admixed/substituted and adulterated samples effectively.19

Several analyses of crude samples of R. crenulata rhizome confirmed that the rhizome does not contain rosavin, but does contain salidroside and other p-tyrosol derivatives, a class of compounds also found in R. rosea.15,26 Salidroside is associated with increase of exercise tolerance.27 Another Rhodiola species, R sachalinensis, was found to contain both rosavin and salidroside, but at lower concentrations than R. rosea;23,29 contrarily, a TLC analysis by Kurkin et al.28 did not find any rosavins in R. sachalinensis.23,29Booker et al. verified the identity of 45 commercial samples (labeled to contain R. rosea [N = 11], R. crenulata [N = 7], R. sachalinensis [N = 4], R. quadrifida [N = 3] or Rhodiola spp. [N = 20]), collected from retailers, local markets, and the internet in China and the United Kingdom, by HPTLC and 1H NMR with subsequent statistical analysis. An analysis of the 11 samples labeled to contain R. rosea indicated that eight (72.7%) contained other Rhodiola species, with four samples containing R. crenulata and one R. serrata23,29 Three of the seven purported R. crenulata samples were also composed of the incorrect species, containing either R. serrata (N = 2) or an unknown material (N = 1).

An unpublished investigation from 2008 by researchers of the University of Ottawa and the Montreal Botanical Garden of the quality of 20 commercial products sold as tablets, capsules, or liquid extracts on the North American market found salidroside (14.4-45.7 mg/g of product) and rosavins (6.1-68.5 mg/g of product) to be present in every sample. The data, obtained using HPLC-UV, suggest that these products contained authentic R. rosea rhizome and root (A. Cuerrier [Montreal Botanical Garden] email to S. Gafner, November 8, 2016).

3.3 Accidental vs intentional substitution: Both intentional and accidental Rhodiola substitution seems to occur during collection based on anecdotal (A. Bily and C.Pierron [Naturex], oral communication to E. Bejar, September 29, 2016) and scientific evidence. 23,29,30 This has been confirmed in a systematic field collection study, which identified several factors contributing to a substitution of Rhodiola species: (1) the lack of genuine raw material, (2) confusion over the (vernacular) Chinese pinyin name of the plant when sourcing from China, and, (3) deliberate substitution during the (collection and) manufacturing of a dietary supplement. 23 In the Altai region, an area in southern Siberia in Russia, there are 24 different species of the genus Rhodiola that could be misclassified as R. rosea by collectors.15

Resource depletion and habitat destruction have led to the disappearance of Rhodiola species in many locations, as most raw materials are wildcrafted and the plant needs several years to regenerate. In some geographical areas, the two most frequently used species, R. crenulata and R. rosea, are becoming vulnerable or at-risk (one source uses the terms “threatened” and “critically endangered” when referring to specific areas),31 making them more expensive to obtain. 23,30,31

Lack of proper collection procedures and the possible interchangeability of Rhodiola species may also contribute to R. rosea and/or R. crenulata being frequently substituted by or accidentally substituted with other Rhodiola species. The fact that most Rhodiola species (in particular, R. rosea and R. crenulata) are morphologically distinct suggests that the lack of raw material definitions and collection guidelines leads collectors to pick or substitute with whatever Rhodiola is locally available. After removal of the aboveground parts, the similarity in the root/rhizome morphology makes it practically impossible to distinguish one species macroscopically from the other and separate them before processing, although they can be distinguished chemically.

Different Rhodiola species, including R. rosea and R. crenulata, can be found on the Chinese market. Often, these are neither sold separately nor well-identified; therefore, there is a high potential of substitution and admixing among these species. While R. crenulata root/rhizome is preferred over R. rosea in TCM, this species is sometimes substituted with R. rosea, R. serrata, or other Rhodiola species. 23,30

The prevalence of R. crenulata on the Chinese market is most likely due to its greater abundance; it is not considered to be a substitute or an adulterant for R. rosea. Overall, the Chinese market is driven by Chinese names, not Latin names, and the Chinese name hong jing tian as an umbrella term generally refers to multiple species of Rhodiola, of which R. crenulata is the most abundant in trade. In China, it is rare for vendors to differentiate the various species, and most vendors have little knowledge about rhodiola because it has a short history of use in TCM and trade. They sell it because it is popular as a general health food item but most vendors know little about it beyond its province of origin, which does not always correlate to the species or morphological form.

As certain Rhodiola species, e.g., R. rosea and R. crenulata, are becoming scarce in the field, other Rhodiola species such as R. fastigiata, R. quadrifida, R. sacra, and R. serrata appear to be replacing them in the market. 32 For example, in a recent analysis of raw material samples purchased from drug stores and hospitals in China, only 40% of the samples labeled to contain R. crenulata were conclusively identified as such, while 40% were replaced with R. serrata, and the remaining samples with other Rhodiola species. 32As demand for the rhizome of R. rosea and R. crenulata increases, so does the cost, creating a greater risk that species substitution will occur.

Although substitution of R. rosea products with R. crenulata is considered the main problem with respect to authenticity of R. rosea species, 19,29 field work data suggest that other species are being implicated. A particular case is R. sachalinensis, a species that has a similar composition to R. rosea, containing rosavins (the marker compounds used to identify R. rosea), as well as salidroside, and is considered by some botanists to be the same species as R. rosea.23,32,33 To complicate matters, different populations of R. sachalinensis may display differences in their high-performance liquid chromatography-ultraviolet detection (HPLC-UV) fingerprints, making accurate species identification based on chemical analysis difficult.32However, substitution with R. sachalinensis may become less of a concern, since its growing range has decreased significantly and it is now considered to be critically endangered in China.Conversely, as the various species of Rhodiola are used interchangeably within traditional systems, differentiation may be necessary only when claiming to sell a specific species.

3.4 Possible safety issues: According to an assessment report by the European Medicines Agency and a more recent safety review, ingestion of R. rosea is considered safe.4,34 Although no assessments of R. crenulata or other Rhodiola species that might be used as substitutes have been published, there are no apparent health concerns when R. rosea is substituted with other materials from the same genus. There is a report about herb-drug interactions based on the fact that Rhodiola species rhizomes contain various amounts of salidroside. Salidroside has been found to significantly inhibit CYP3A4, which is an important drug-metabolizing enzyme. Although the potential for this interaction is based mostly on in vitro data, one clinical case report suggests this could be of clinical relevance leading to amplification of the effects of drugs with CYP3A4 mediated metabolism.34

3.5 Analytical methods to detect substitution: Roots and rhizomes of R. rosea can be distinguished from roots/rhizomes of R. crenulata and other Rhodiola species by trained experts using botanical, TLC, HPLC, NMR, and genetic methods. The color of the flower allows distinguishing R. rosea from R. crenulataand other purple-flowering species botanically.8,9,12,35 Dried rhizomes of various Rhodiola species, however, cannot be differentiated macroscopically from one another, but can be distinguished by chemical comparisons to authentic reference materials.

One of the approaches to distinguish R. rosea rhizome from other Rhodiola species is the presence/absence of rosavins by TLC. The first TLC method to detect rosavins was reported by Kurkin et al.28 Several other methods have been developed since then, including an HPTLC method with very clear criteria to distinguish R. rosea from other Rhodiola species.23,36,37

Kurkin et al. noted that salidroside was common in the genus Rhodiola, but among 11 Rhodiola species that were tested, only R. rosea contained the rosavins, allowing one to use the presence or absence of these compounds to possibly differentiate among species.28 The lack of rosavins in R. sachalinensis was later refuted by other researchers.23,29 Various HPLC methods have been reported in the literature to distinguish R. rosea chemically from other species. 38-40 The use of rosarin, rosavin, and rosin as marker compounds is critical to ensure identity of R. rosea products. Identification of R. rosea products containing other Rhodiola species may require not only identification of the presence of the rosavins, but also quantification of the amount of each and their ratios. Other methods have been suggested, including NMR-based metabolomics, 23,41 and HPTLC. The suite of methods appears to be helpful in detecting irregularities in commercial R. rosea products.

A DNA barcoding approach to identify Rhodiola species, based on 189 accessions representing 48 of the 55 species of Rhodiola described in the Flora of China,7 has been reported.42 The results suggested that the internal transcribed spacer (ITS) genomic region was best suited for use as a single-locus barcode, resolving 66% of the Rhodiola species. Combining five loci (rbcLmatKtrnH-psbAtrnLF, and ITS) increased the resolution to 81% of the species. However, the DNA method may not be considered adequate when used alone in quality control procedures, since close to 20% of species cannot be distinguished, and also due to the inability to discern the plant part. Various DNA-based approaches have also shown little success in species identification of highly processed botanical ingredients, e.g., extracts.

4          Conclusions

Substitution or mixing of R. rosea root/rhizome raw material and extracts with other species, especially R. crenulata, remains an issue of regulatory concern for manufacturers and marketers of products labeled as R. rosea. Substitution of R. rosea with other Rhodiola species can be detected botanically and through chemical analysis (e.g., HPTLC, HPLC and NMR). The increasing scarcity of wildcrafted R. rosea and R. crenulata, as well as reliance on complex supply chains involving many stakeholders (especially many collectors in diverse regions, particularly in China), is increasing the likelihood for substitution and admixing with other Rhodiola species, particularly R. fastigiata, R. quadrifida, R. sacra, and R. serrata.

5                 References

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  3. Moran RV. Rhodiola rosea. Flora of North America. Vol 8. New York, NY and Oxford, United Kingdom: Flora of North America North of Mexico. 20+ vols.; 1993-2017:167.
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  6. Rhodiola quadrifida Fisch & Mey and Rhodiola rosea L. Medicinal Plants in Mongolia. Geneva, Switzerland: World Health Organization (WHO); 2013:163-172.
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  8. Rhodiola roseaUSP 40 – NF 35. Rockville, MD: United States Pharmacopeial Convention; 2017:6805-6807.
  9. Cuerrier A, Tendland Y, Rapinski M. Ethnobotany and conservation of Rhodiola species. In: Cuerrier A, Ampong-Nyarko K, eds. Rhodiola rosea. Boca Raton, FL: CRC Press; 2014.
  10. Rhodiola rosea. Germplasm Resources Information Network [Internet]. United States Department of Agriculture, Agricultural Research Service; 1998. Available at: https://npgsweb.ars-grin.gov/gringlobal/taxonomydetail.aspx?31156. Accessed May 24, 2017.
  11. Rhodiola crenulataPharmacopoeia of the Peoples Republic of China. Vol 1. Beijing, China: China Medical Science; 2010:376-377.
  12. Rhodiola. In: Wu Y-Z, Raven PH, eds. Flora of China. Vol 8. Beijing, China and St. Louis, MO: Missouri Botanical Garden Press; 2001:251-268.
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  15. Panossian A, Wikman G, Sarris J. Rosenroot (Rhodiola rosea): traditional use, chemical composition, pharmacology and clinical efficacy. Phytomedicine. 2010;17(7):481-493.
  16. Hartwich M. The importance of immunological studies on Rhodiola rosea in the new effective and safe herbal drug discovery. Centr Eur J Immunol. 2011;35(4).
  17. Rhodiola rosea. Therapeutic Research Faculty; 2007.
  18. Anonymous. Rhodiola rosea. Monograph. Altern Med Rev. 2002;7(5):421-423.
  19. Booker A, Jalil B, Frommenwiler D, et al. The authenticity and quality of Rhodiola rosea products. Phytomedicine. 2016;23(7):754-762.
  20. Moley T, Foster S, Awang D, Hu SY, Kartesz JT, Tucker AO. Herbs of Commerce. 1st ed. Austin, TX: American Herbal Products Association; 1992.
  21. Smith T, Kawa K, Eckl V, Johnson J. Sales of herbal dietary supplement sales in US increased 7.5% in 2015. HerbalGram. 2016;111:67-73.
  22. Smith T, Kawa K, Eckl V. Herbal supplement sales in US increase 7.7% in 2016. HerbalGram. 2017;115:56-65.
  23. Booker A, Zhai L, Gkouva C, Li S, Heinrich M. From traditional resource to global commodities: a comparison of Rhodiola species using NMR spectroscopy-metabolomics and HPTLC. Front Pharmacol. 2016;7:254.
  24. Lichius JJ, Loew D. Rhodiola rhizoma et radix. In: Blaschek W, ed. Wichtl – Teedrogen und Phytopharmaka. 6th ed. Stuttgart, Germany: Wissenschaftliche Verlagsgesellschaft mbH; 2016:554-555.
  25. Ma Y-C, Wang X-Q, Hou F, et al. Rapid resolution liquid chromatography (RRLC) analysis for quality control of Rhodiola rosea roots and commercial standardized products. Nat Prod Commun. 2011;6(5):645-650.
  26. Ma C-Y, Tang J, Wang H-X, Gu X-H, Tao G-J. Simultaneous determination of six active compounds in Rhodiola L. by RP-LC. Chromatographia. 2008;67(5):383-388.
  27. Xu J, Li Y. Effects of salidroside on exhaustive exercise-induced oxidative stress in rats. Mol Med Rep.6(5):1195-1198.
  28. Kurkin VA, Zapesochnaya GG, Shchavlinskii AN, Nukhimovskii EL, Vandyshev VV. Method of analysis of identity and quality of Rhodiola rosea rhizome. Khim Farm Zh. 1985;19(3):185-190.
  29. Booker AJ, Zhai L, Heinrich M. A metabolomic and phytochemical based study of Rhodiola species sourced from Asia and Europe. Planta Med. 2015;81(16):SL3A_03.
  30. Xin T, Li X, Yao H, et al. Survey of commercial Rhodiola products revealed species diversity and potential safety issues. Sci Rep. 2015;5:8337.
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  32. Zhao W, Shi X, Li J, Guo W, Liu C, Chen X. Genetic, epigenetic, and HPLC fingerprint differentiation between natural and ex situ populations of Rhodiola sachalinensis from Changbai Mountain, China. PLoS One. 2014;9(11):e112869.
  33. The Plant List. Version 1.1 Available at: http://www.theplantlist.org. Accessed May 19, 2017.
  34. Semple H, Bugiak B. Toxicology and safety of Rhodiola rosea. In: Cuerrier A, Ampong-Nyarko K, eds. Rhodiola rosea. Boca Raton, FL: CRC Press; 2014.
  35. Compositional guideline: Rhodiola rosea dried root (powdered) extract. In: Aging DoHa, ed. Symonston, ACT, Australia: Therapeutic Goods Administration; 2012:1-3.
  36. Rumalla C, Avula B, Ali Z, et al. Quantitative HPTLC analysis of phenylpropanoids in Rhodiola species. J Plan Chromatogr – Modern TLC. 2011;24(2):116-120.
  37. Rhodiola rosea root (Rhodiola rosea). HPTLC Association. Available at: http://www.hptlc-association.org. Accessed May 24, 2017.
  38. Ganzera M, Yayla Y, Khan IA. Analysis of the marker compounds of Rhodiola rosea L. (golden root) by reversed phase high performance liquid chromatography. Chem Pharm Bull 2001;49(4):465-467.
  39. Wang Q, Ruan X, Jin Z-h, Yan Q-c, Tu S-j. Identification of Rhodiola species by using RP-HPLC. J Zhejiang Univ Sci B. 2005;6(6):477-482.
  40. Avula B, Wang Y-H, Ali Z, et al. RP-HPLC determination of phenylalkanoids and monoterpenoids in Rhodiola rosea and identification by LC-ESI-TOF. Biomed Chromatogr 2009;23(8):865-872.
  41. Ndjoko Ioset K, Nyberg NT, Van Diermen D, et al. Metabolic profiling of Rhodiola rosea rhizomes by (1)H NMR spectroscopy. Phytochem Anal. 2011;22(2):158-165.
  42. Zhang JQ, Meng SY, Wen J, Rao GY. DNA barcoding of Rhodiola (Crassulaceae): a case study on a group of recently diversified medicinal plants from the Qinghai-Tibetan Plateau. PLoS One. 2015;10(3):e0119921.

Revision Summary

Version # , Author Date Revised Section Revised List of Changes
Version 1, E. Bejar, R. Upton, J.H. Cardellina II n/a n/a none

Rooibos Tea: Research into Antioxidant and Antimutagenic Properties

Antioxidants are hot topics in the health news these days, and a herbal tea called rooibos (pronounced ROY-boss) is becoming popular partly because it is being marketed as a healthy beverage with high levels of antioxidants. The rooibos plant (Aspalathus linearis (Burm. f.) Dahlgren, Fabaceae) is a South African flowering shrub used to make a mild-tasting tea that has no caffeine, very little tannin, and significant amounts of polyphenol antioxidants. Although the tea is new to many Americans, it has been made in the Cedarberg mountain region of South Africa for generations. Distributors are promoting the tea for numerous health benefits, citing recent studies that show some antioxidants found in rooibos tea may protect against cancer, heart disease, and stroke. What’s the evidence for these claims?

A Note on Tea Terminology

In the strict sense, the word tea has been reserved for infusions made from leaves of the evergreen shrub Camellia sinensis (L.) Kuntze, Theaceae, while infusions made from herbs such as rooibos have been called tisanes. Over time, however, the common use of the word tea has been extended to include herbal infusions, and this relaxed usage is followed here. Rooibos is often referred to as red tea because it makes a vibrant red-colored tea, which can be confusing because black tea and hibiscus herbal tea are also sometimes called red tea.

Botanical Description

Rooibos is a shrubby legume that is indigenous to the mountains of South Africa’s Western Cape.1-3 The genus Aspalathus includes more than 200 species native to South Africa.2-5 Alinearis is a polymorphic species; various wild forms have been described, each with characteristic morphology and geographical distribution.1-3 Some forms are prostrate and remain less than 30 cm (1 foot) tall, while other forms grow erect and may reach up to 2 m (about 6 feet) in height.1-3,6 The types of wild rooibos that have been used to make tea are sometimes referred to as the Red, Black, Grey, and Red-Brown types.1,2

The type of A. linearis that is cultivated commercially for tea is the Red type, also known as the Rocklands type;1,6 it is native to the Pakhuis Pass area in the northern Cedarberg region.6 The Rocklands type grows erect, up to 1.5 m (about 5 feet) in height. It has a single basal stem that divides just above the ground surface into multiple thin branches that carry bright green, needle-like leaves of about 10—40 mm (0.4—1.6 inches) in length.7 The plant produces small yellow flowers in spring through early summer,6 and each flower generates a one-seeded leguminous fruit.4,5

Rooibos has adapted to coarse, nutrient-poor, acidic soil and hot, dry summers.4,5,8 In addition to a network of roots just below the soil surface, the plant has a long tap root that reaches as deep as 2 m (about 6 feet) and helps the plant find moisture during summer drought.5 As a legume, rooibos contains nodules of nitrogen-fixing bacteria on its roots; this characteristic helps the plant survive in the poor Cedarberg soils and minimizes the need for fertilizing commercial crops with nitrogen.8 The bacteria convert nitrogen dioxide to biologically useful ammonia in a process known as nitrogen fixation. The plant absorbs the nitrogen and benefits from it in exchange for providing the bacteria with food sources created from photosynthesis.

One study found genetic variations between four morphologically different populations of A. linearis.1 The authors suggest that the wild forms of A. linearis might be used to improve characteristics, such as yield and disease resistance, of the cultivated form. They also observe that because the cultivated Rocklands form is being grown outside of its original Pakhuis Pass location, this introduction of the cultivated form into new areas could threaten the genetic integrity of the wild forms in these areas.

A later study7 showed genetic differences between populations of A. linearis that are sprouters (plants that can resprout from a deep rootstock to regenerate after a fire) and populations that are seeders (plants that rely on producing plentiful seeds to reproduce). The authors suggest that reseeding is the primitive character state in A. linearis and resprouting is a derived state that evolved to help the plant survive in a region prone to wildfires. The rooibos plant that is commercially grown for tea is the seeder type.7

In addition to differences in morphology and genetics, researchers have found differences in chemistry between various populations of A. linearis.6,9 Van Wyk, of the Department of Botany at Rand Afrikaans University, presented results of his tests on the different wild populations of rooibos, showing significant variations in the polyphenol profile by population.9

Historical Background

More than 300 years ago, indigenous inhabitants of the mountainous regions of South Africa’s Western Cape were the first to collect wild rooibos and use it to make tea.10 These people discovered that they could brew a sweet, tasty tea from rooibos leaves and stems that they cut, bruised with wooden hammers, fermented in heaps, and then sun-dried. Botanists first recorded rooibos plants in 1772 when they were introduced to the tea by the Khoi people.10

Rooibos became a cultivated crop by the early 1930s, has been grown commercially since World War II, and now is exported to countries worldwide, including Germany, Japan, the Netherlands, England, Malaysia, South Korea, Poland, China, and the United States.10 In 1999, about 29 percent of South Africa’s total rooibos sales were exported to 31 countries.10 The quantity of rooibos exported in 2000 was two and a half times greater than the quantity exported in 1999, and exports continue to grow.10 The small towns of Clanwilliam and Wupperthal, north of Cape Town in the Cedarberg region, have a long history of rooibos cultivation; these towns are popular tourist stops because of their beautiful rural scenery and their role in the rooibos industry.

Roughly 70 percent of the bulk rooibos that is exported goes through Clanwilliam-based Rooibos Ltd. <www.rooibosltd.co.za>, a partnership of private growers/processors and a cooperative of large and small farmers in the area. The rooibos is sold in a variety of products in Europe, Asia, and, increasingly, America. Other South African companies that market rooibos tea products include Khoisan, Cape Natural Tea Products, and Coetzee & Coetzee. International demand for rooibos has been increasing since trade sanctions against South Africa were lifted following the demise of apartheid in the 1990s. Since 1999, the nonprofit organization Agribusiness in Sustainable Natural African Plant Products (ASNAPP, <www.asnapp.org>) has helped small farmers in and around Wupperthal to introduce sustainable methods of rooibos cultivation that allow them to compete in the world market. ASNAPP is sponsored by the U.S. Agency for International Development, Rutgers University, and Stellenbosch University. Through Stellenbosch University, ASNAPP also helped the farmers at Wupperthal fund construction of a tea court to process rooibos.

Rutgers University provides a quality control program for ASNAPP’s Wupperthal tea program, evaluating parameters such as color, taste, aroma, pH, moisture content, cleanliness, total phenol content, and antioxidant capability for tea samples collected from the industry in general and from all the growers in the Wupperthal tea program.11 Data from their analyses are made available to the farmers and also to prospective buyers via product specification sheets.

The Perishable Products Export Control Board (PPECB) of South Africa ensures that all exported rooibos products pass a phytosanitary inspection and are certified to be free of bacteria and impurities.4,10 In order to pass these health and safety tests, rooibos producers steam pasteurize the tea as the final step before packing. Organic rooibos is also monitored by various international organizations that provide organic certification, such as the German firms Ecocert and Lacon.

Harvesting and Processing: Fermented and Unfermented Rooibos

When rooibos is cultivated commercially, the needle-like leaves and stems are usually harvested in the summer, which corresponds to January through March in South Africa.4 The plants are cut to about 30 cm (1 foot) from the ground at harvest time and begin another major growth cycle the following spring. The harvested rooibos is processed two different ways, producing two types of tea. The green leaves and stems are either bruised and fermented or immediately dried to prevent oxidation. The traditional fermented tea is processed today in much the same way as the indigenous people processed it hundreds of years ago, including the sun-drying step, but the tools are more sophisticated now.

The fermented type is called red tea because fermentation turns the leaves and the resulting tea a rich orange/red color; this distinctive color led to the Afrikaans name rooibos, which means “red bush.” The unfermented type, often called green rooibos, contains higher levels of polyphenol antioxidants because fermented rooibos loses some antioxidants during the fermentation process. The unfermented type was developed to maximize antioxidant levels in response to recent interest in the health benefits associated with the antioxidants found in C. sinensis teas. Unfermented rooibos tea is a tan/yellow color rather than the rich reddish color of fermented rooibos.

Both types of rooibos tea are available plain or flavored, loose or in tea bags, organic or conventionally grown. Rooibos is graded according to color, flavor, and cut length, with the highest grade labeled “supergrade.” The tea has a smooth, non-bitter flavor that is pleasant hot or chilled. The unfermented variety has a very mild “green” taste reminiscent of green tea but without the astringency; the fermented type is quite different, with a stronger sweet and fruity taste. The mild flavor of rooibos has made it popular in multi-ingredient herbal tea blends.

Antioxidants in Rooibos

Free radicals (unstable molecules that have lost an electron) can damage the DNA in cells, leading to cancer, and they can oxidize cholesterol, leading to clogged blood vessels, heart attack, and stroke. Antioxidants can bind to free radicals before the free radicals cause harm. Some antioxidants are called polyphenols because these substances contain a phenolic ring in their chemical structure. Polyphenols are common in plants; they act as pigments and sunscreens, as insect attractants and repellants, and as antimicrobials and antioxidants.12,13 The polyphenol group is further divided into subgroups such as flavonoids and phenolic acids. Polyphenols can also be classified as monomeric (molecules containing a single unit) or polymeric (larger molecules containing more than one unit). As described in this section, laboratory studies have found that rooibos tea contains polyphenol antioxidants, including flavonoids and phenolic acids, that are potent free radical scavengers.

Flavonoids: The polyphenol antioxidants identified in rooibos tea include the monomeric flavonoids aspalathin, nothofagin, quercetin, rutin, isoquercitrin, orientin, isoorientin, luteolin, vitexin, isovitexin, and chrysoeriol.14-19 Currently, rooibos is the only known natural source of aspalathin.15 Nothofagin is similar in structure to aspalathin and has only been identified in one other natural source besides rooibos: the heartwood of the red beech tree (Nothofagus fusca (Hook F.) Oerst, Nothofagaceae), which is native to New Zealand.20

A recent analysis of fermented rooibos measured the levels of all the flavonoids listed above except nothofagin (see Table 1).19 Of the 10 flavonoids measured, the three that occurred in largest amounts were aspalathin, rutin, and orientin, followed by isoorientin and isoquercitrin. Nothofagin was identified by mass spectrometry but was not quantified because a standard was not available. The amount of nothofagin in fermented and unfermented rooibos was estimated to be about three times less than aspalathin in one study.20 Aspalathin and nothofagin arepresent in relatively large amounts in unfermented rooibos tea,19,20but some of the aspalathin and nothofagin oxidizes to other substancesduring fermentation; thus, fermented rooibos contains less aspalathin and nothofagin than unfermented rooibos.20 The change in polyphenol composition is the reason the tea changes color with fermentation.20

Phenolic Acids: In addition to flavonoid antioxidants, rooibos also contains phenolic acids that have been shown to have antioxidant activity.14,18,21 Like flavonoids, phenolic acids are polyphenol substances that are found in fruits, vegetables, and whole grains. The phenolic acids identified in rooibos tea, in decreasing order of antioxidant activity as measured in one study21 with the commonly used 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay, include caffeic acid, protocatechuic acid, syringic acid, ferulic acid, vanillic acid, p-hydroxybenzoic acid, and p-coumaric acid.14,18 Using the DPPH assay, caffeic acid was just as active an antioxidant as the most potent flavonoids tested (quercetin, isoquercitrin, and aspalathin).21

Total Polyphenol Content: Despite some promotional claims, a serving of rooibos tea has less total polyphenols than the same size serving of green or black tea. Serving size varies, but for comparison purposes a 150 to 200 ml serving is often used (about 3/4 of a standard baking measuring cup). Elizabeth Joubert, Ph.D., specialist researcher at South Africa’s ARC Infruitec-Nietvoorbij and a rooibos expert, says that the total polyphenol content of an average 150 to 200 ml serving of rooibos tea can be as much as 60 to 80 mg, depending on factors such as the brewing time and amount of leaves used.22 For comparison, one study found that brewing black tea leaves for 1 to 3 minutes at a concentration of 1 g leaves per 100 ml water resulted in black tea that contains 128 to 199 mg of polyphenols per 200 ml serving of tea.23 The types of polyphenols in rooibos tea are different than those in green and black teas, so the potential health benefits of the teas cannot be compared solely on their total polyphenol content. Rooibos tea does not contain epigallocatechin gallate (EGCG), which is a polyphenol in green tea that has shown anticarcinogenic and antioxidant capabilities, but many of the polyphenols in rooibos tea are also strong antioxidants.

Quercetin and Luteolin: Two of the flavonoids in rooibos tea, quercetin and luteolin, are potent antioxidants found in many fruits and vegetables. Studies in vitro (in the test tube) have shown that these antioxidants can cause cancer cells to “commit suicide,” referred to as apoptosis.24-27 Quercetin decreased primary tumor growth and prevented metastasis in a model of pancreatic cancer.25 Luteolin and quercetin inhibited proliferation of thyroid28 and colon29 cancer cells, respectively, in vitro. Quercetin inhibited cyclooxygenase-2 (COX-2) expression in colon cancer cells, which may help prevent colon cancer.30,31 Both luteolin and quercetin can block the formation of lipid peroxides.32-34

Although studies like these show quercetin and luteolin are strong antioxidants, researchers haven’t yet determined whether enough of either of these two flavonoids are present in rooibos tea and absorbed by the body to have beneficial effects. As shown in Table 1, recent analysis of fermented rooibos found considerably more quercetin than luteolin,19 but even quercetin was present in much lower amounts than aspalathin, orientin, and rutin.

Based on the data in Table 1, a 150 ml serving of fermented rooibos tea made with 2.5 g of tea leaves has about 0.27 mg of quercetin; for comparison, one study found that C. sinensis contains 1.5 to 3.75 mg of quercetin per 150 ml serving of tea.35 A previous study36 found 1.5 mg of quercetin per 150 ml serving of fermented rooibos, but that may be an upper limit. Joubert says that the 1.5 mg estimate is probably high,22 but emphasizes that these estimates will vary with parameters such as the brewing time and the amount of water and tea leaves used. At any rate, the amount of quercetin per serving of rooibos is a small percentage of the total polyphenol content per serving of rooibos.

Aspalathin and Nothofagin: A unique polyphenol that is one of the most abundant monomeric flavonoids in rooibos tea,19,20 aspalathin seems to contribute to the antioxidant capabilities of rooibos,21 but aspalathin is not as well studied as quercetin and luteolin. Nothofagin is similar in structure to aspalathin and may have similar antioxidant capabilities.

Joubert says that chief research technologist Petra Snijman of the Program on Mycotoxins and Experimental Carcinogenesis (PROMEC) at the Medical Research Council of South Africa recently developed a way to isolate pure aspalathin and nothofagin from rooibos. Joubert says, “According to unpublished in vitro studies done at ARC Infruitec-Nietvoorbij, aspalathin compared well with quercetin in terms of antioxidant activity, except in a fat medium where quercetin demonstrated much higher potency than aspalathin. What is important in these comparative studies is the test environment. Relative efficacy will depend on the test system used (the polarity of the medium, the type of free radical that needs to be scavenged, etc.).”22

Joubert co-authored a study21 that found aspalathin compared well to other antioxidants with the DPPH radical scavenging assay. The study measured the antioxidant capability of many of the flavonoids and phenolic acids found in rooibos tea and compared them to several reference standards such as alpha-tocopherol (vitamin E). The percent inhibition of the DPPH radical by quercetin, isoquercitrin, aspalathin, rutin, luteolin, and alpha-tocopherol was 98.27, 91.99, 91.74, 91.18, 90.85, and 75.10, respectively (using a 0.25 mole ratio of antioxidant to DPPH). All of the flavonoids tested showed potent hydrogen donating abilities with DPPH except for vitexin, which only had a 7.26 percent inhibition even at a 0.5 mole ratio to DPPH.

According to the data in Table 1, a 150 ml serving of fermented rooibos made with 2.5 g of tea leaves has about 3 mg of aspalathin; since the amount of nothofagin was measured to be three times less than aspalathin in one study,20 a 150 ml serving of fermented rooibos has on the order of 1 mg of nothofagin. A serving of unfermented rooibos has considerably more aspalathin and nothofagin than an equal serving of fermented rooibos because a portion of these flavonoids oxidizes to other substances during fermentation.20

Orientin and Rutin: Orientin and rutin are two of the other most abundant monomeric flavonoids in rooibos,19 and both have been associated with health benefits. Orientin is a potent free radical scavenger. It reduced by half the number of cancer-associated changes in cells of human blood exposed to radiation.38When mice were exposed to radiation, orientin protected against lipid peroxidation in the liver and also reduced damage to the bone marrow and gastrointestinal tract.39,40 Rutin, a flavonoid found in buckwheat (Fagopyrum esculentum Moench, Polygonaceae) and some fruits and vegetables, seems to help maintain the strength of capillary walls; oral rutin as well as oral and topical o-(beta-Hydroxylethyl)-rutoside (HR) have been used to treat hemorrhoids, varicose veins, and the lower leg edema associated with venous insufficiency and venous hypertension.41-46 According to the data in Table 1, a 150 ml serving of fermented rooibos tea made with 2.5 g of tea leaves has about 2.5 mg of orientin and 3.2 mg of rutin.

Total Antioxidant Capability: Although the 10 flavonoids in Table 1 are important because they are known to have antioxidant properties, they only represent a small percentage of the total polyphenol content of a serving of fermented rooibos tea. A 150 to 200 ml serving of rooibos can have up to 60 to 80 mg of total polyphenols,22 and Table 1 shows that a 150 ml serving of fermented rooibos made with 2.5 g of leaves has about 14 mg of the 10 flavonoids in the table. Many other polyphenols are present, but they have not all been identified or quantified.

To assess the antioxidant capability of rooibos tea as a whole, researchers compared the antioxidant activity of rooibos tea extracts to that of green and black tea extracts with the DPPH radical scavenging assay as well as the beta-carotene bleaching method.47 All the teas showed strong antioxidant activity with both methods. Using the DPPH method, the ranking from highest to lowest antioxidant activity was green tea (90.8 percent inhibition), unfermented rooibos (86.6 percent), fermented rooibos (83.4 percent), and black tea (81.7 percent). Green tea was significantly higher than the others (< 0.05), but the other three teas did not differ from each other significantly with respect to DPPH inhibition. Using the beta-carotene bleaching method, the ranking was green tea, black tea, fermented rooibos, and unfermented rooibos. The relative ranking varies with the type of test because the substance to be tested will have different reactivity to the different oxidizing agents used. These tests only measure the antioxidant capability of substances outside of the body and don’t provide data on whether the antioxidants are absorbed by the body and effective after the food is consumed.

In this study, all the tea extracts were diluted to the same amount of soluble solids rather than to the amounts of solids found in the teas.47 This method allows a comparison of antioxidant capability on a mass equivalent basis, but does not reflect a comparison of the antioxidant strength of equal volume servings of the teas. Although the soluble solid content varies with the method of tea preparation, it usually decreases in the order green tea, black tea, unfermented rooibos, fermented rooibos.47 The percent of soluble solids represented by polyphenols is similar for the four teas and the DPPH antioxidant activity is similar on a mass equivalent basis, so the DPPH antioxidant capability of equal-sized servings will decrease in the order of the soluble solid content.47 Black and green teas have over twice as much soluble solids as rooibos tea when prepared conventionally, so over two 200 ml servings of rooibos tea would need to be consumed to receive the same antioxidant benefit (as measured by DPPH) as one 200 ml serving of black or green tea (or the rooibos would need to be brewed to twice the standard concentration).47 This result agrees with the data given previously for 60 to 80 mg polyphenols for a 150 to 200 ml serving of rooibos tea22 as compared to 128 to 199 mg polyphenols for a 200 ml serving of black tea.23

The studies referenced above show that rooibos tea contains antioxidants that have positive effects when tested as isolated substances and that the tea as a whole has good antioxidant activity in vitro. So, do all these antioxidants in rooibos tea lead to health benefits for tea drinkers?

Rooibos Research in Live Animals and Animal Cells

Laboratory studies have demonstrated potential health benefits of rooibos in vitro (in test tubes) and in vivo (in live animals), but human studies have not been conducted. Much more research is needed, but the studies so far look intriguing.

Fermented Rooibos against Mutagens: Researchers found that fermented rooibos tea reduced cancer-associated changes in animal cells induced by the mutagens benzo[a]pyrene (B(a)P) and mitomycin C (MMC) both in vitro and in vivo.48 The in vitro part of the study measured chromosomal aberrations in animal cells caused by exposure to the mutagens. The cells were treated with tea extract either at the same time as the mutagen or after the mutagen. Some of the tests used rat liver microsomal enzyme, called S9, to provide metabolic activation of the mutagen; B(a)P requires metabolic activation, but MMC can act with or without it.

Both green tea and rooibos tea suppressed aberrant cells caused by B(a)P and MMC in the presence of S9, but rooibos showed a greater suppression of aberrant cells than did green tea (see Table 2). In fact, when the cells were exposed to B(a)P and S9 simultaneously with rooibos tea, the highest concentration of rooibos tea (1000 microgram/ml) completely inhibited the aberrant cells, bringing their percentage down to the level of the controls that were not exposed to any mutagen. Also, rooibos tea suppressed aberrant cells caused by MMC both with and without the presence of S9, but green tea showed no suppression without S9. Treating the cells simultaneously with the mutagen and tea extract caused a greater protective effect than treating the cells with tea extract following exposure to the mutagen (compare Tables 2 and 3).

In the in vivo part of this study, mice were given oral doses of tea and an injection of B(a)P or MMC.48 The researchers measured the frequency of micronucleated reticulocytes (MNRETs), which are cells with damaged DNA that may lead to cancer. In one experiment, a single oral dose of tea (1 ml of 0.2 percent green tea or 0.1 percent rooibos tea) was given 6 hours prior to an injection of MMC and the number of MNRETs was counted at 24, 48, and 72 hours after the MMC. Rooibos tea and green tea provided similar inhibition of the frequency of MNRETs. After 48 hours, rooibos tea reduced the level of MNRETs by about 34 percent, and green tea reduced the level by about 38 percent. When the mice received the single dose of tea either after the mutagen or 24 hours prior to the mutagen, neither green tea nor rooibos tea reduced the frequency of MNRETs.

When the teas were given as one oral dose daily for 28 days and then the mutagen was injected on day 29, both rooibos tea and green tea reduced the frequency of MNRETs caused by B(a)P. Daily doses of 0.2 percent green tea reduced MNRETs by about 62 percent 48 hours after B(a)P exposure, and daily doses of 0.1 percent rooibos tea reduced MNRETs by about 49 percent. Daily doses of 0.1 percent rooibos tea reduced MNRETs by about 34 percent 48 hours after MMC exposure, but daily doses of green tea did not provide a significant reduction with MMC.

Fermented Rooibos against Irradiation: Another research group found that extract of fermented rooibos tea reduced cancerous transformation of mouse cells exposed to x-rays in vitro.49 The amount of protection correlated with the dose of rooibos, and an extract concentration of 10 percent reduced the cell transformations to a level similar to the spontaneous level of the controls. Interestingly, green tea in equivalent concentrations did not show any detectable protective effect. In another study, fermented rooibos tea reduced cell damage in live mice that were exposed to irradiation two hours following a single dose of rooibos administered by gastric intubation.34

Fermented Rooibos against Brain Lipid Peroxidation: Rats given fermented rooibos tea daily ad libitum (free access) from the age of 3 months to 24 months had greatly reduced age-related lipid peroxide accumulation in four areas of their brains compared to rats that drank plain water.50 Increases in lipid peroxides in the brain may damage neuronal cells and contribute to age-related diseases.50 The lipid peroxide levels were evaluated by measuring the amounts of thiobarbituric acid reactive substances (TBARS) in eight regions of the brain. The 24-month-old rats that had been drinking plain water had significantly higher TBARS in the frontal cortex, occipital cortex, hippocampus, and cerebellum compared to 5-week-old rats, but the 24-month-old rats that had been drinking rooibos tea had no increase in TBARS in those four areas of the brain. The TBARS of the 24-month-old rooibos group were similar to the TBARS of the young 5-week-old group (see Table 4).

The authors give a bar chart that summarizes the TBARS data for each area of the brain.50 The TBARS values in nmol/g for 24-month-old rats without rooibos tea, 24-month-old rats given rooibos tea, and 5-week-old rats, respectively, were approximately 120, 80, 80 in the frontal cortex; 115, 70, 80 in the occipital cortex; 80, 40, 50 in the hippocampus; and 115, 80, 85 in the cerebellum. The authors say these results suggest that the administration of rooibos tea protected several regions of the rat brain against lipid peroxidation accompanying aging. Magnetic resonance images taken of the brain were consistent with the TBARS data.

Fermented vs. Unfermented Rooibos:Another study found that both fermented and unfermented rooibos tea exhibits antimutagenic properties in vitro as measured by the Salmonella typhimurium mutagenicity assay with several different mutagens; the antimutagenic activity was stronger against the metabolically activated mutagens 2-acetylaminofluorene (2-AAF) and aflatoxin B1 (AFB1) than it was against three direct-acting mutagens.51 Further research showed that the fermentation process causes a decrease in the antimutagenic and antioxidant activity of rooibos tea as measured by the Salmonella typhimurium mutagenicity assay (with 2-AAF), the hydrogen donating ability (assessed with DPPH), and the superoxide anion radical scavenging assay.52 The researchers suggest that fermented rooibos may show less antioxidant and antimutagenic activity because it has less polyphenols than unfermented rooibos. One analysis showed that polyphenols represent about 41 percent of the total solid matter in unfermented rooibos tea extract, but only about 30 percent of the total solid matter in fermented rooibos tea extract.51

One of the authors of both these studies is senior research scientist Jeanine Marnewick of the Program on Mycotoxins and Experimental Carcinogenesis (PROMEC) at the Medical Research Council of South Africa. She says, “Rooibos showed protective effects against DNA damage when tested in an in vitro assay as well as in an in vivo animal system.” 53 The in vitro studies found unfermented rooibos was generally more protective against DNA damage than fermented rooibos. But Marnewick says her group’s research shows that fermented rooibos has a stronger effect against some mutagens. She says, “Both the fermented and unfermented rooibos showed a significant protection, and we’re busy elucidating the mechanisms.”53 She is currently evaluating the protective effect of rooibos on liver, esophageal, colon, and skin cancer induced in live animal models. The studies are in the early phases and she cautions, “Very little is known about the effect of rooibos on cancer development.” 53

Joubert also adds a cautionary note, saying that many questions about rooibos still need to be answered.22She says that researchers need to determine which of the antioxidant substances in rooibos tea are absorbed by the body and how much tea is needed to produce a measurable benefit. She also emphasizes that no human studies have been conducted yet.

Whole Foods vs. Isolated Antioxidants: The full benefits of teas are likely to come from a combination of all the antioxidants in them rather than from just one substance. Quite a few studies have found that isolated antioxidants don’t have as positive an anticancer effect as the mixture of antioxidants found in natural food sources; whole apple extracts were better than pure quercetin at inhibiting the growth of cancer cells in vitro,13,54 tomato powder was better than pure lycopene at extending the life of rats with prostrate tumors,13,55 and freeze-dried strawberries exhibited better anticancer properties in animals than did pure ellagic acid.13,56 Also, white and green tea extracts demonstrated better antimutagenic propertiesin vitro than mixtures of nine polyphenols found in the teas (mixed according to their relative proportions in the teas).57 Researchers believe these results indicate that other substances in the whole food products besides the identified antioxidants probably contribute to the total anticancer effect of the food, and that the relative amounts of all these substances could be important. Different teas have different mixtures of antioxidants, and they will protect against different mutagens. Sorting out all of these interactions will take time.

Rooibos Folklore: What’s Proven?

Although rooibos does contain active antioxidants, many of the other health claims made for rooibos tea are not well documented (based only on anecdotal evidence) or are not supported by science. Researchers are still investigating many of these claims to evaluate all the potential benefits of rooibos.

Vitamins And Minerals: Despite some promotional claims that rooibos is a source of vitamin C, Joubert says it is not. “We have tested both the traditional rooibos and green rooibos, and vitamin C was not present,” she says.22

With the exceptions of fluoride and copper, the trace amounts of minerals in rooibos are not enough to make the tea a meaningful dietary source of minerals for the average consumer. As shown in Table 5, the nutritional labeling that is given on some packages of rooibos tea and on some websites of distributors4,5indicates that the amounts of iron, potassium, zinc, calcium, and magnesium in a 200 ml serving of rooibos tea are all less than 1 percent of the U.S. reference daily intake (RDI). A 200 ml serving of rooibos provides over 5 percent of the RDI of fluoride for adults and over 7 percent of the RDI for copper (see Table 5). Marc S. Micozzi, M.D., Ph.D., director of the Policy Institute for Integrative Medicine in Bethesda, Maryland, notes that when rooibos is used as a fluid replacement throughout the day, as is done with some athletes in South Africa, it does provide measurable amounts of several minerals and electrolytes.58

Colic, Allergies, And Other Ailments:Distributors of rooibos tea often suggest it can help allergies, sleep problems, digestive problems, headache, and other ailments,4,5but these claims have not been verified by scientific research. If the indigenous people of the Cedarberg region used rooibos tea medicinally, that tradition was lost and rooibos was just enjoyed as a good-tasting beverage until the recent interest in its health benefits.10 Many of the health claims for rooibos tea began in 1968 when a South African woman, Annekie Theron, found that rooibos tea eased her infant’s colic.10 As the story goes, she found no documentation on the benefits of rooibos and began her own experiments with local babies who had colic and allergies.10 She concluded that rooibos helped these babies, and she published a book in 1970 titled Allergies: An Amazing Discovery. Since then, she patented a rooibos extract that is now used in cosmetic products, and she started her own line of health and cosmetic products.10

Today, South African physicians recommend rooibos for infant colic.59 South Africans also use it to calm digestive upset in adults, to help induce sound sleep, and topically to sooth eczema, skin allergies, and diaper rash.59 Not enough research has been done to know if these folk remedies really are effective or to identify the substances in the tea that might be responsible for any observable benefits. Joubert says the tea does seem to help infant colic, but no formal studies have been done.22

Immune Function: An in vitro and in vivo study showed that rooibos might enhance immune function, but very little research has been done on this topic.60 One study found that a polysaccharide in rooibos leaves may have antiviral activity against the HIV virus, but the polysaccharide had to be chemically extracted from the leaves and is not found in tea made by steeping the leaves in water.61 There’s no evidence that rooibos tea fights the HIV virus.

Zero Caffeine And Low Tannin: Several other health advantages of rooibos tea that are often mentioned are its zero caffeine content and its low tannin content. Because rooibos is naturally caffeine-free, it does not have to be subjected to a decaffeination process and, therefore, does not lose any of its polyphenol content (as occurs when green and black teas are decaffeinated). The zero caffeine content also means rooibos can be enjoyed by those who want to avoid the stimulating effects of caffeine and can be consumed in quantity by those who want to use it as a fluid replacement.

Rooibos only has about 4.4 percent tannin content,51 which means that it does not have the astringent taste associated with C. sinensis and will not become bitter even after long steeping times. Rooibos tea can be a good alternative to C. sinensis for people who prefer the milder taste of a less astringent herbal tea or for those who have digestive problems with tannin-rich beverages. And as Micozzi observes, some people can receive a higher total antioxidant intake from rooibos than from green or black tea because the low tannin content and caffeine-free nature of rooibos allow it to be consumed in larger quantities.58

Iron Absorption: Other disadvantages have been attributed to tannins; they can bind to non-heme iron (iron from non-meat sources), reducing iron absorption, and they can decrease the metabolism and utilization of proteins.62-69 Black and green teas reduce the amount of non-heme iron absorbed by the body when the tea is consumed at the same time as the iron source.62-66 These effects do not cause problems for most people, but they can cause problems for people who have nutritionally marginal diets or low intake of heme iron sources (meats).69

Other polyphenol-rich beverages besides C. sinensis teas can also inhibit iron absorption. One study found that the inhibition of iron was 79 to 94 percent for black tea, 84 percent for peppermint tea, 73 percent for hot cocoa, and 47 percent for tea of chamomile (Matricaria recutita L., Asteraceae).62 The teas still inhibited iron absorption to the same degree even if milk was added to them. Some of these beverages contain only low levels of tannins, but other polyphenols in foods and beverages can also reduce iron absorption.62,64The ability of polyphenols to chelate prooxidant metal ions might provide some antioxidant protection, but it can also be a disadvantage by decreasing absorption of necessary dietary minerals such as iron.64

The low tannin content of rooibos is sometimes used to infer that rooibos tea won’t inhibit iron absorption, but that conclusion is not automatic since rooibos is rich in other polyphenols that might decrease iron absorption. In one small study, three groups of 10 young healthy men were given an oral dose of iron, followed by rooibos tea, C. sinensis tea, or plain water.71 Iron absorption was measured to be 7.25 percent for rooibos tea, 1.70 percent for C. sinensis tea, and 9.34 percent for plain water. The result for C. sinensis was significant (P < .0001), but the data for rooibos did not reach statistical significance (that is, the data for rooibos were not good enough to determine whether this result can be generalized to the whole population or whether the result was just chance). More studies are needed to better document the effect of rooibos on iron absorption, but this study implies that rooibos might not inhibit iron absorption nearly as much as C. sinensis tea.

The Bottom Line

Rooibos tea has become popular because of its fruity, sweet taste and its caffeine-free, low tannin, antioxidant-rich status. Although more research is needed, rooibos appears to be safe and free of side effects. The antioxidants present in rooibos may help protect against free radical damage that can lead to cancer, heart attack, and stroke. Unfermented (green) rooibos has a higher amount of polyphenols than traditional fermented rooibos and generally demonstrates higher antioxidant and antimutagenic capabilities in vitro. Future research should reveal whether the antioxidant benefits of rooibos observed in vitro and in animals translates into health benefits for humans.


The author thanks Elizabeth Joubert, Ph.D., specialist researcher at South Africa’s ARC Infruitec-Nietvoorbij, and Jeanine L. Marnewick, senior research scientist at the Program on Mycotoxins and Experimental Carcinogenesis (PROMEC) at the Medical Research Council of South Africa, for their quotes and technical input, as well as for providing copies of several research papers. Their expertise on rooibos has contributed much valuable information to this article. Lorenzo Bramati, Ph.D., research scientist at the Instituto Tecnologie Biomediche CNR in Italy, provided helpful input and copies of several research papers. Erica Renaud, a member of the quality control program for ASNAPP (Agribusiness in Sustainable Natural African Plant Products) at the Center for New Use Agriculture and Natural Plant Products at Rutgers University provided valuable input and photos. Marc S. Micozzi, M.D., Ph.D., director of the Policy Institute for Integrative Medicine, offered helpful review and comments. Rooibos Ltd./SunnRooibos also provided valuable insight and photos.

Laurie Erickson, a freelance writer in Mountain View, California, is interested in the medicinal and horticultural aspects of herbs. She began investigating rooibos out of personal curiosity and has no financial connections with the rooibos industry. Her educational background includes a B.S. in Environmental Earth Science and an M.S. in Geomechanics from Stanford University. She has also written the medical website <http://www.tendinosis.org> and has been published in the garden section of several newspapers.


1. Van der Bank M, Van Wyk B-E, Van der Bank H. Biochemical genetic variation in four wild populations of Aspalathus linearis (rooibos tea). Biochem Syst Ecol 1995;23(3)257-262.

2. Dahlgren R. Revision of the genus Aspalathus II. The species with ericoid and pinoid leaflets. 7. Subgenus Nortieria, with remarks on rooibos tea cultivation. Bot Notiser 1968;121,165-208.

3. Dahlgren R. Aspalathus. In Flora of Southern Africa. National Botanical Institute, Pretoria. 1988;16(3,6)1-430.

4. Rooibos Limited website: <www.rooibosltd.co.za>. (Rooibos Ltd. is the largest producer/distributor of rooibos in South Africa.)

5. Red Bush Tea website: <http://www.redbushtea.com>. Text discusses the tap root; also see photo of rooibos seedling with tap root on this site.

6. Van Wyk B-E, Van Oudtshoorn B, Gericke N. Medicinal Plants of South Africa. Briza Publications, Pretoria, South Africa. 1998. 304 p. Online condensed version available at <http://www.african-medicines.com>.

7. Van der Bank M, Van der Bank FH, van Wyk B-E. Evolution of sprouting versus seeding in Aspalathus linearisPlant Syst Evol 1999;219(1,2)27-38.

8. Muofhe ML, Dakora FD. Nitrogen nutrition in nodulated field plants of the shrub tea legume Aspalathus linearis assessed using 15N natural abundance. Plant and Soil 1999;209(2)181-6.

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