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.


Hops Extract Improves Anxiety, Depression, and Stress Symptoms in Healthy Young Adults

The female inflorescence of hops (Humulus lupulus, Cannabaceae) is used traditionally to treat insomnia, excitability, and restlessness. The German Commission E approved the use of hops for sleep disturbances and mood disorders such as anxiety and restlessness; however, according to the authors, there is a lack of high-quality, placebo-controlled studies evaluating the efficacy of hops in reducing stress-related symptoms. Hence, the purpose of this randomized, placebo-controlled, double-blind, crossover study was to assess the effects of the commercially available hops dry extract on depression, anxiety, and stress levels in healthy young adults.

Healthy students (n = 42, aged > 18 years) attending Harokopio University in Athens, Greece, with at least mild self-reported symptoms of depression, anxiety, and stress according to the Depression Anxiety Stress Scale-21 (DASS-21) participated in the trial (study dates not reported). Exclusion criteria were any systemic disease (e.g., neurological or psychiatric disorders, including clinically diagnosed anxiety disorders and depression) or systemic treatment (e.g., sedatives, antidepressants, or supplements), changes in body weight > 3% of total body weight within the past 2 months, changes in physical activity levels within the past 2 months, and drug and/or alcohol use disorders.

Subjects were treated with either 400 mg/day hops dry extract (Melcalin® HOPs; Biotekna Srl; Marcon, Venice, Italy) or placebo (not described; Biotekna Srl) for 4 weeks and then were crossed over to the alternate treatment after a 2-week washout period. Subjects were asked to abstain from consuming products containing hops (i.e., beer), taking other supplements/vitamins (i.e., valerian [Valeriana officinalis, Caprifoliaceae] root or St. John’s wort [Hypericum perforatum, Hypericaceae] aerial parts), and significantly changing dietary and activity habits. At the beginning and end of each study period, anthropometric measurements were taken; symptoms of depression, anxiety, and stress were assessed with the DASS-21; and blood was collected to measure morning cortisol plasma levels. Adverse events (AEs) were collected via diary throughout the study.

Of the 42 subjects enrolled in the study, 6 (14.2%) did not complete the first treatment per protocol and were excluded from the analysis (3 in the hops group and 2 in the placebo group discontinued treatment, and 1 in the placebo group was lost to follow-up). Neither group had significant changes in body weight, body mass index, body composition parameters, or plasma cortisol levels (P > 0.05 for all).

Compared to placebo, the hops treatment significantly decreased DASS-21 subscores for anxiety (P = 0.009), depression (P = 0.001), and stress (P = 0.009). There were no significant correlations between any of the DASS-21 subscale scores and the other study variables (anthropometric measurements and plasma cortisol levels). There were no AEs reported for either group.

According to the authors, the extant literature on the clinical effects of hops pertains to trials evaluating combination products containing hops and this is the first placebo-controlled, randomized study to provide evidence that hops monotherapy significantly improves measures of self-reported depression, anxiety, and stress in otherwise healthy young adults. Cautions have been published regarding the use of hops in people with depression because the known sedative effects may heighten depressive symptoms and potentiate the soporific effects of antidepressant drugs; however, the results of the present study “suggest that hops may have an overall beneficial mood-enhancing effect without significant adverse/side effects in treatment-naïve individuals presenting with symptoms of both depression and anxiety/stress.”

Acknowledged limitations of this study include potential recruitment/selection bias, the use of subjective measures (although the DASS-21 is a well-validated instrument), the results cannot be generalized to other populations, only morning cortisol levels were measured (there may be diurnal variations), and other stress biomarkers were not assessed. The authors conclude, “Longer studies are required to explore the long-term efficacy and safety of this intervention, which should be also studied in older patients with depression and/or anxiety/stress disorders.”

This publication conformed with the Consolidated Standards of Reporting Trials (CONSORT) guidelines, except for the reporting of funding sources. The Melcalin HOPs and placebo treatments were provided by Biotekna Srl. The authors report no conflict of interest.


Kyrou I, Christou A, Panagiotakos D, et al. Effects of hops (Humulus lupulus L.) dry extract supplement on self-reported depression, anxiety and stress levels in apparently healthy young adults: a randomized, placebo-controlled, double-blind, crossover pilot study. Hormones (Athens). 2017;16(2):171-180.


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

  1. McGuffin M, Kartesz JT, Leung AY, Tucker AO. American Herbal Products Association’s Herbs of Commerce. 2nd ed. Silver Spring, MD: American Herbal Products Association; 2000.
  2. Brown R, Gerbarg P, Ramazanov Z. Rhodiola rosea – a phytomedicinal overview. HerbalGram. 2002;56:40-52.
  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.
  4. Assessment report on Rhodiola rosea L., rhizoma et radix London, United Kingdom: European Medicines Agency Committee on Herbal Medicinal Products (HMPC); 2011:1-32.
  5. Community herbal monograph on Rhodiola rosea L., rhizoma et radix. London, United Kingdom: European Medicines Agency Committee on Herbal Medicinal Products (HMPC); 2012:1-5.
  6. Rhodiola quadrifida Fisch & Mey and Rhodiola rosea L. Medicinal Plants in Mongolia. Geneva, Switzerland: World Health Organization (WHO); 2013:163-172.
  7. Powdered Rhodiola rosea extract. USP 40 – NF 35. Rockville, MD: United States Pharmacopeial Convention; 2017:6809-6810.
  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: 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.
  13. Bohm BA. The Geography of Phytochemical Races. Dordrecht, Netherlands: Springer Netherlands; 2009.
  14. Rhodiola – Rhodiola rosea. Ottawa, ON, Canada: Natural Health Products Directorate, Health Canada; 2013.
  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.
  31. Allen D, Bilz M, Leaman DJ, Miller RM, Timoshyna A, Window J. European Red List of Medicinal Plants.Luxembourg, Luxemburg: Publications Office of the European Union; 2014.
  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: 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: 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

Health Benefits of Butterbur

Butterbur has a plant extract used in alternative remedies. But what are its health benefits and are there any risks involved in using it?

Butterbur comes from a shrub that grows in Europe, Asia, and parts of North America, and is available as a natural remedy in many health food stores and pharmacies. It is most commonly used to treat migraines and hay fever, although it has a number of other potential uses.

What is butterbur?

Butterbur plant and flower.
Butterbur extract comes from the bulb, leaf, and roots of the plant.

The proper name for the butterbur plant is petasites hybridus. It grows best in wet marshland, damp forest soil, or on riverbanks.

The name butterbur is thought to come from the fact that its large leaves were traditionally used to wrap butter and stop it from melting in summer.

Butterbur extract is taken from the leaf, roots, or bulb of the plant.

The use of butterbur to treat ailments can be traced back to the Middle Ages when it was used to fight the plague. Over the centuries it has been used to treat a range of conditions, including:

  • wounds
  • coughs
  • asthma

Today it is most commonly used to treat:

  • headaches and migraines
  • allergies, such as hay fever
  • upset stomachs
  • urinary tract infections

Uses of butterbur

This section explores the modern day uses of butterbur and the scientific evidence available to support them.


Butterbur may be able to treat the symptoms of migraines and may make attacks less frequent.

The most popular use of butterbur is in the treatment of migraines and headaches. Scientific research shows that this use is well-founded.

2011 review found butterbur to be a safe and effective treatment for migraines, especially at high doses.

Researchers noted that the exact way butterbur works to relieve migraines is unknown. However, they believe it has to do with the anti-inflammatory effects of the active components.

A 2012 review conducted on behalf of the American Academy of Neurology and the American Headache Society found that butterbur is effective for migraine prevention.

The review recommends that butterbur should be offered to people who experience migraines to reduce the frequency and severity of their attacks.

Hay fever

Butterbur is often used to treat allergic rhinitis, commonly known as hay fever.

2007 review of existing studies found that there is encouraging evidence that suggests butterbur may help to treat seasonal allergic rhinitis.

However, the review called for further studies to be done to confirm the findings because three of the trials that found butterbur to improve allergic rhinitis symptoms were funded by a company that manufactured butterbur products.

Upset stomachs

Some people use butterbur to treat stomach upsets and find it to be effective. However, there is little scientific evidence to support this use.

2011 review noted that studies have found that butterbur may actually cause stomach problems. Researchers found that problems with digestion, such as belching, were a side-effect of taking butterbur.

More research is needed to support the claim that butterbur is an effective treatment for an upset stomach.

Urinary tract infections

As the active chemicals in butterbur help reduce spasms and inflammation, some people believe butterbur could help treat urinary tract infections.

However, there is not sufficient scientific evidence to support the claim that butterbur can combat urinary tract infections.

How butterbur works

Butterbur contains two chemicals called petasin and isopetasin. These chemicals help to reduce spasms and inflammation. It is the action of these chemicals that are thought to give butterbur its health benefits.

Butterbur is sold in a number of forms, including:

  • extracts
  • capsules
  • powders
  • tinctures
  • gels

There are several things to consider before deciding to take butterbur. As with any natural remedy, it is a good idea for an individual to speak to a doctor to check how butterbur may interact with any existing medications they may be taking.

Additionally, the U.S. Food and Drug Administration (FDA) do not regulate the quality or sale of butterbur, so a person should always buy natural remedies from a reputable source.

Check the label

Depending on how they are prepared, butterbur remedies may contain chemicals called pyrrolizidine alkaloids (PAs). These are known to damage the liver and can cause serious illness.

Teas and other raw or unprocessed butterbur products are likely to contain PAs and should be avoided.

It is only safe to take butterbur products that are certified as “PA-free,” as these products have been processed in a way that removes the dangerous chemicals.

Be aware of side effects

While most people tolerate butterbur well, some may experience side effects. Side effects can include:

  • headaches
  • itchy eyes
  • diarrhea
  • breathing difficulties
  • fatigue
  • drowsiness

Avoid if sensitive to plants

Butterbur may cause an allergic reaction in people who are sensitive or allergic to other plants and plant products. In these cases, it should be avoided.

Avoid long-term use

While studies have looked at the short-term use of butterbur, there are no studies that look at long-term use of the plant. Consequently, it is not known if long-term butterbur use is safe.

It is best to take butterbur only to provide short-term relief.

Using “PA-free” natural remedies containing butterbur is safe for most people, but a person should still use caution and research the brand and potential side effects. Some people may experience mild side effects, especially if they have a sensitivity to plants.

Butterbur has been shown to be effective in treating migraines. The evidence of its use to treat hay fever is encouraging, but research is ongoing.

Based on current research, there is little evidence to support the use of butterbur to treat other ailments.

Proper Brewing of Rooibos Tea

There’s no need to be intimidated by brewing rooibos tea, even if it is less well known. In fact, brewing this tea is very similar to brewing the average cup of black tea. Still, there are a lot of factors that affect the finished product, including proper storage of rooibos tea leaves, water type and temperature, and steeping time. Practice the following steps and tips, and you’ll always create a delicious and nutritious cup of rooibos.

Storing your tea leaves

Tea leaves of all varieties are generally delicate and should be handled and stored in the correct manner. For the best tasting and healthiest tea, make sure to store rooibos tea leaves in a dry and cool location like a cupboard. Also, the container the tea is in should be opaque and airtight so that light and smells cannot affect the tea. When you’re ready for brewing rooibos tea, these storage techniques should ensure that the tea leaves retain their flavor and antioxidants and produce an excellent final product.

Brewing Rooibos Tea

While brewing tea entails remembering a few essentials, the process will become habitual after a few attempts. Don’t worry if you need to refer to these instructions several times before feeling confident in your brewing technique.

Step 1: The Water – It’s always best to use spring water or filtered water when brewing rooibos tea, as the tea will have the purest taste possible. One type of water to always avoid is distilled water, which will not properly release the intense flavor of rooibos tea leaves.

As for water temperature, it is preferable to brew rooibos tea leaves in heartily boiling water and keep the water hot for the entire time the leaves are steeping. One tip to keep the water warm is to place your steeping cup of tea on stove surface near the burner you just used.

Step 2: The Tea – Personal opinion differs greatly on how much tea should be used for each cup, but in general those who like weaker tea use fewer leaves than those who like stronger tea. The standard ratio of tea to water, however, is one heaping teaspoon of tea leaves per eight ounces (one cup) of water.

Step 3: Steeping – Rooibos tea has a longer steeping time than most other teas. The shortest amount of time it should steep is four to five minutes, but studies have shown that steeping rooibos tea for five to ten minutes greatly increases the amount of antioxidants and nutrients in the finished cup.

Brewing rooibos tea and enjoying it in its natural form always creates a delectable cup, but many people also like to serve the tea with milk and sugar or honey for a little added sweetness. Rooibos tea also creates a wonderful iced tea that can be infused with a variety of flavors.

Where to buy rooibos tea: Organic Kosher Rooibos Red Tea & African Herbs Gourmet Tea, Naturally Caffeine Free, Very Little Tannic Acid And More Antioxidants

Rooibos Tea Consumption Acutely Increases Plasma Antioxidant Capacity

Pre-clinical studies have shown that rooibos (Aspalathus linearis) tea possesses antioxidant effects.1 This antioxidant activity has been primarily attributed to polyphenolic constituents that include the unusual compounds aspalathin and nothofagin, as well as caffeic acid, protocatechuic acid, quercetin, rutin, isoquercitrin, and others.1 Fermentation of rooibos tea oxidizes many of these polyphenolic compounds. This randomized, placebo-controlled, crossover, clinical study was the first to assess the antioxidant capacity of both fermented and unfermented rooibos tea in healthy human subjects.

Beverage Partners Worldwide (Zurich, Switzerland) provided 500 mL bottles of fermented and unfermented rooibos teas containing 1.5 g/L rooibos extract powder for the study. The authors recruited 15 healthy nonsmokers who did not take medications or antioxidant supplements. For 2 days prior to the study, the subjects followed a low-antioxidant diet that excluded fresh fruits and vegetables, tea, coffee, and wine. The subjects kept dietary records to ensure that they did not consume high-antioxidant foods and beverages. The subjects were randomized into 3 groups (randomization method not stated): group A received 500 mL water (control), group B received 500 mL fermented rooibos tea, and group C received 500 mL unfermented rooibos tea. Venous blood samples were collected 0, 0.5, 1, 2, and 5 hours after the subjects drank the tea. Following 2-week wash-out periods, the subjects were crossed over to the other treatments until all patients had received all treatments. The researchers measured the total antioxidant capacity (TAC) of the subjects’ plasma and the teas using the total radical-trapping antioxidant potential (TRAP) assay. In addition, they measured the subjects’ levels of plasma glucose, total cholesterol, triglycerides, and urate.

The in vitro results showed that unfermented rooibos tea has a 28% higher TAC than fermented rooibos tea (unfermented: 5.23 ± 0.80 mmol/L; fermented: 4.07 ± 0.29 mmol/L). The authors comment that both fermented and unfermented rooibos teas “possess a lower chain-breaking antioxidant potential than do green and black teas [Camellia sinensis] but higher than commercially available instant tea.”

There were no significant changes in the subjects’ plasma triglyceride, uric acid, or total cholesterol levels. Their plasma glucose levels increased significantly compared to baseline 30 minutes after drinking the fermented and unfermented rooibos teas (fermented: +32.0%, P<0.001; unfermented: +21.6%, P<0.001), but not water. The authors do not provide information about product formulation, but this increase could be due to sweetener added to the teas. Water did not affect the subjects’ plasma TRAP values. Plasma TRAP values increased compared to baseline 30 minutes after the subjects drank the fermented rooibos tea (+4.8%), and the increase was statistically significant 1-hour post-ingestion (+6.6%, P<0.05 compared to baseline and control). The subjects’ plasma TRAP values increased 30 minutes after drinking the unfermented rooibos tea (+1.7%), and the difference was statistically significantly higher than the control 1 hour (+2.9%, P<0.01) and 2 hours post-ingestion (+2.7%, P<0.05). Although still significantly higher than baseline values, the subjects’ plasma TRAP values started to decline at 2 hours post-ingestion (+4.9%, P<0.05 compared to baseline). The subjects’ plasma TRAP values returned to baseline levels 5 hours after ingestion. The authors failed to mention the presence or absence of adverse side effects. No withdrawals from the study were reported.

This is the first clinical study to show that rooibos tea acutely increases plasma antioxidant levels in human subjects. It is interesting to note that, while the unfermented rooibos tea showed a greater antioxidant capacity compared to the fermented tea in vitro, the in vivo results show that fermented tea has a greater effect on plasma TRAP values compared to the unfermented rooibos tea. This raises questions about bioavailability. Further clinical studies to confirm these results and to examine the effect of chronic rooibos tea consumption on antioxidant status are warranted.


Villano D, Pecorari M, Testa M, et al. Unfermented and fermented rooibos teas (Aspalathus linearis) increase plasma total antioxidant capacity in healthy humans. Food Chem. 2010;123(3):679-683.

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. <>, 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, <>) 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 <> and has been published in the garden section of several newspapers.


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Ergogenic Effects of Tongkat Ali

Tongkat Ali (Eurycoma longifolia, Simaroubaceae), also known as long jack, is a dioecious flowering shrub widely distributed in Southeast Asia and Indochina. An aqueous decoction of its roots is used traditionally to promote sexual health and fertility and to counter the effects of ageing. It is reported to have anti-inflammatory, antimalarial, antimicrobial, and antioxidant activity. Other traditional uses include as an anxiolytic and for its antiulcer and anticancer effects. Tongkat Ali’s composition includes alkaloids such as β-carboline and cathine-6-one, flavonoids, phenolics, saponins, tannins, propanoids such as scopolin and propan, biphenylneolignans, and triterpenes such as tirucallane and eurylene. It is rich in quassinoids, including eurycolactones A-F, eurycomalactone, hydroxylongilactone, dehydroklaineanone, 15β-O-acetyl-14-hydroxyklaineanone, eurycomanol, eurycomanone, and eurycomaoside, all thought to contribute to its salutary effects on muscle strength, endurance, and reduced anxiety and stress.

These latter effects fall within the realm of ergogenics. An ergogenic aid is defined as any means of enhancing energy use, production, control, or efficiency. Besides mechanical and psychological ergogenic aids, other types are physiological, pharmacological, and nutritional. Pharmacological ergogenic aids might include manufactured drugs as well as natural substances. Consumption of various herbs is a common ergogenic practice, often intended to boost endurance and strength in sports. The authors review evidence regarding the use of Tongkat Ali as an ergogenic aid.

The authors, without disclosing their search strategy, review available evidence concerning ergogenic benefits of Tongkat Ali. Four human studies are discussed. A randomized, double-blind study evaluated the effects of a Malaysian herbal drink containing Tongkat Ali (0.1 mg/100 mL), cassia (Cinnamomum aromaticum syn. C. cassia, Lauraceae; 2.0 mg), calcium (2.9 mg), sodium (1.1 mg), and potassium (0.9 mg). Cyclists received 3 mL/kg body weight of the herbal drink or the same amount of placebo (colored water) every 20 minutes during bouts of exercise. Cycling time before exhaustion was longer for the active group, but not significantly so. Researchers concluded that both the herbal drink and water acted ergogenically in this study. In another study, 12 recreational athletes took two capsules (150 mg) of Tongkat Ali or placebo daily for seven days. No difference was found between the groups in endurance, running performance, or physiological responses. Other researchers, with a longer study time of five weeks and a dose of 100 mg per day, reported that Tongkat Ali can increase fat-free mass, muscle strength, and muscle size. [Note: The review incorrectly states 150 mg.] In addition, it is suggested that the aphrodisiac effects of Tongkat Ali may be due to stimulation of androgen production. Androgen, the main male sex hormone, is responsible for testosterone production; however, the use of testosterone supplements in organized sports is forbidden. In another study, 13 male recreational athletes took 400 mg of Tongkat Ali or placebo daily for six weeks and it was reported that the urinary testosterone level of those in the active group remained below the cutoff point of the International Olympic Committee Medical Commission and that Tongkat Ali caused no adverse effects on subjects’ liver and kidney functions. It is not stated whether this study found any performance benefits for Tongkat Ali supplementation.

Another clinical study evaluated the effects of Tongkat Ali supplementation (200 mg) vs. placebo on stress hormones and mood in 63 subjects. At four weeks, the active group showed significant improvements, with decreased tension, anger, and confusion, as well as in stress marker profiles, with reduced cortisol and increased testosterone levels.

Tongkat Ali’s effects on endurance and energy use are more pronounced at higher doses and with longer supplementation times. Future studies should examine its effects on mood more closely to determine if the herb’s ergogenic effects are mediated by improvements in mood.

An appended table lists several other herbs studied or used for anti-fatigue, antistress, and endurance-enhancing effects, but it is by no means exhaustive, and these herbs are not discussed.


Khanijo T, Jiraungkoorskul W. Review ergogenic effect of long jack, Eurycoma longifoliaPharmacogn Rev. July-December 2016;10(20):139-142.


Proprietary Bilberry Fruit Extract (Mirtoselect®) May Aid in Dry Eye Syndrome

Dry eye is a chronic disease that can damage the eye’s surface and diminish the quality of life and work productivity. Dry eye complications include discomfort, vision changes, compromised tear film, and inflammation of the eye’s surface. Bilberry (Vaccinium myrtillus, Ericaceae) extract may be beneficial in promoting eye health. In a previous study, Mirtoselect® (Indena S.p.A.; Milan, Italy), a natural bilberry extract with standardized anthocyanins derived from bilberry fresh frozen fruit, outperformed a generic bilberry extract in improving “retinal circulatory parameters.”1 The purpose of this study was to investigate Mirtoselect’s bioavailability, its ability to relieve dry eye symptoms, and its potential as an antioxidant.

First, an in vivo pharmacokinetic study was performed. The authors did not state where this study occurred. Five male rats were given “bilberry dried extract derived from Vaccinium myrtillus L. fresh frozen fruits (Mirtoselect®, Indena, Milan, Italy), containing 36% anthocyanins and matching the full phytochemical profile of the whole fruit,” while 5 other male rats were given “a highly purified anthocyanin-rich extract, containing 89% anthocyanins and devoid of the non-anthocyanin fraction … .” The dosage was 400 mg/kg body weight, dissolved in water, and administered by mouth. The rats’ blood was then drawn at 5, 10, 15, 20, 30, 45, 60, 90, and 120 minutes after treatment, processed and evaluated by an ultraviolet (UV) spectrophotometric method at 530 nm. The area under the curve (AUC) was higher for the Mirtoselect group than for the group receiving the highly purified anthocyanin-rich fraction (202.34 ± 24.23 µg·min/ml versus 130.93 ± 4.93 µg·min/ml). Calculation of the dosage-adjusted AUC value ratios revealed that anthocyanosides were 4 times more bioavailable in the Mirtoselect group than in the anthocyanin-rich group.

Next, Mirtoselect was compared to placebo in a 4-week, randomized, double-blinded, parallel-group, comparison study conducted at Ario Nishi-Arai Eye Clinic; Tokyo, Japan. Healthy subjects (n=22; ages 30-60) had visual fatigue or eye strain; at least 4 hours daily of video game, PC, or video display terminal (VDT) use; corrected visual acuity of at least 1.0 decimal (20/20 feet) for both eyes; and no regular ingestion of pharmaceuticals or health foods known to alleviate eye strain. Exclusion criteria included a history of cardiac failure or infarction, treatment for chronic disease, allergies to a component of the investigated products, using contact lenses, eye diseases, entropion palpebrae (introverted eyelids), smoking, poor diet, insufficient sleep, pregnancy, breastfeeding, and childbearing potential. Subjects took 2 tablets of Mirtoselect or placebo daily for 4 weeks. Each dietary supplement tablet contained 80 mg of Mirtoselect and 170 mg of excipients. The placebo tablets contained only excipients.

To recreate VDT visual load, subjects were instructed to play for 45 minutes on a video game console before an examination. Clinical and ophthalmological tests were completed at inclusion and 4 weeks later. Tear flow was quantified with Schirmer’s test (which determines whether the eye produces enough tears to keep it moist); pupil constriction was measured with TriIRIS® C9000 (Hamamatsu Photonics K.K.; Hamamatsu City, Japan; a machine that can monitor the accommodation and convergence function simultaneously) before and after visual load (pupil constriction was used as a surrogate marker for eye strain); diacron-reactive oxygen metabolites (d-ROMs) test was used to evaluate oxidative stress; and biological antioxidant potential (BAP) was used to evaluate antioxidant potential. Modified BAP/d-ROMs ratio was used to comprehensively assess antioxidant potential.

Eleven subjects were randomly assigned to the Mirtoselect dietary supplement group and 11 to the placebo group. One dropped out of the placebo group for personal reasons. It was not reported if the demographic data were balanced.

Schirmer’s test revealed that, after 4 weeks, subjects receiving Mirtoselect had significantly more tear secretion from the right eye (19.5 ± 7.3 mm; P<0.01) and from both eyes (19.7 ± 8.6 mm; P<0.05), but not from the left eye (P=0.062), as compared to baseline. [Note: Data are expressed as the mean ± standard deviation.] The placebo group did not have statistically significant findings for Schirmer’s test values after 4 weeks compared to baseline (right eye, P=0.361; left eye, P=0.118; both eyes, P=0.177). Mean improvement rates from baseline to 4 weeks were higher in the Mirtoselect group compared to the placebo group for the right eye, left eye, and both eyes, with a statistically significant difference for the right eye (P=0.049). When the groups were further divided into severe versus mild symptoms (the authors did not define these terms), the severe Mirtoselect group had a statistically significantly higher improvement rate than the mild Mirtoselect group for the right eye and for the left eye (right eye, P=0.028; left eye, P=0.023), and among all subjects with severe symptoms, the rate of improvement was greater in the Mirtoselect group than in the placebo group for the right eye (P=0.015).

The pupil constriction test revealed no significant findings (data not shown). From baseline to 4 weeks, BAP increased significantly (P=0.003) in the Mirtoselect group only, while d-ROMs increased significantly (P=0.013) in the placebo group only. The modified BAP/d-ROMs ratio results were not statistically significant (P=0.187, Mirtoselect group; P=0.293, placebo group).

In summary, in the Mirtoselect group, anthocyanosides were more bioavailable and tear secretion increased significantly. In addition, Mirtoselect may be an effective antioxidant. The authors hypothesize Mirtoselect’s non-anthocyanin bilberry components may have aided absorption, and Mirtoselect could be an effective dry eye treatment for some people. To be elucidated are Mirtoselect’s complete pharmacokinetic profile, mechanism of action, and patient-reported outcomes. Five of the authors (Riva, Togni, Franceschi, Kawada, and Inaba) are employees of, and 1 author (Giacomelli) is a consultant for, Indena S.p.A., the manufacturer of Mirtoselect.


1Gizzi C, Belcaro G, Gizzi G, et al. Bilberry extracts are not created equal: the role of non-anthocyanin fraction. Discovering the “dark side of the force” in a preliminary study. Eur Rev Med Pharmacol Sci. 2016;20(11):2418-2424.

Riva A, Togni S, Franceschi F, et al. The effect of a natural, standardized bilberry extract (Mirtoselect®) in dry eye: a randomized, double-blinded, placebo-controlled trial. Eur Rev Med Pharmacol Sci. May 2017;21(10):2518-2525.

Health Benefits of Fennel Tea

In the Middle Ages, on Midsummer’s night, people hung fennel over doorways to protect the household from evil spirits.

Although it is no longer used as a protective decoration, fennel is still one of the more widely used medicinal plants, being suggested for everything from colic to conjunctivitis.

The benefits of fennel tea are both culinary and curative. Fennel is used in many different cuisines, from Indian to Italian, to contemporary fusion, and all parts of the plant are used, including the leaves, seeds, and bulb.

Fast facts on fennel:

  • The Latin name for fennel is foeniculum vulgare.
  • The ancient Greeks and Romans thought fennel could bring strength and fortitude and lead to longer life.
  • The benefits of fennel tea are very similar to those derived from fennel seeds.

What is fennel?

Fennel tea in clear mug, with fennel seed in a bowl and wooden spoon, and a caraway flower,
Fennel tea has long been enjoyed for its flavor, though many choose to drink it for its purported health benefits.

Native to the Mediterranean region, fennel is now found all over the world, and its uses are as numerous as the places in which it grows.

Flavorful and fragrant, fennel is used in the following ways:

  • as a spice
  • eaten raw
  • dried
  • braised
  • grilled
  • shaved
  • stewed

It has a distinctive licorice-like flavor and is used in salads, sausages, ice cream, cookies, alcoholic beverages, pasta dishes, and more.

The history of fennel

Emperor Charlemagne was so taken with fennel that he brought the flowering plant to Europe and grew it on his estates.

Through the ages, many health claims have been made for fennel, and drinking fennel tea is an established practice in traditional medicine throughout the world.

Although Western science has not verified all these benefits, humans have used fennel to:

  • relieve flatulence
  • encourage urination
  • boost metabolism
  • treat hypertension
  • improve eyesight
  • prevent glaucoma
  • regulate appetite
  • clear mucus from the airways
  • stimulate milk production in nursing women
  • speed digestion
  • reduce gas
  • reduce stress
  • detoxify the body

Health benefits

Fennel seeds in a tea strainer over a mug of herbal tea.
Fennel tea may aid healthy digestion, and treat bloating, gas, or cramps, and may also act as a diuretic.

According to herbalists, fennel seed is an effective aid to digestion. It can help the smooth muscles of the gastrointestinal system relax and reduce gas, bloating, and stomach cramps.

In fact, tinctures or teas made from fennel seeds can be used to treat stomach muscle spasms caused by irritable bowel syndrome, ulcerative colitis, Crohn’s disease, and other conditions affecting the gastrointestinal system.

Fennel may also be used in combination with other herbal remedies to modify the side effects of herbal formulas used as laxatives, or other treatments for digestive problems.

1. Painful periods

Painful periods or dysmenorrhoea are a common problem for many women, who often use over-the-counter medications, such as non-steroidal anti-inflammatory drugs (NSAIDs) to treat the pain.

However, roughly 10-20 percent of women who suffer from severe cramping and discomfort during their period do not find relief through this approach.

Many turn to alternative or complementary treatments instead, and a 2012 study suggested that fennel can be helpful in this regard.

Researchers speculate that fennel helps keep the uterus from contracting, which is what prompts the pain reported by women with dysmenorrhea.

2. Colic

One of the significant benefits of fennel is its anti-spasmodic qualities. Because of this, some people believe that fennel tea may also play a role in reducing the symptoms of colic in infants.

3. Regulating blood sugar

Many herbalists and complementary healthcare practitioners recommend fennel tea as a way to regulate blood sugar.

study in Bangladesh, in which mice were treated with an extract made from mentholated fennel seeds, found that, at some dosage levels, this extract reduced blood glucose levels at a rate comparable to that of standard antihyperglycemic medications.

4. Pain relief

Fennel is also considered helpful for pain relief. The same study from Bangladesh found that fennel extract reduced indications of pain at a level close to that provided by aspirin.

5. Hydration

Staying well hydrated is important for overall health, so one of the more direct benefits of fennel tea is that it provides individuals with a tasty, caffeine-free beverage.

Fennel tea or fennel extract?

Extract of fennel seeds is not the same thing as fennel tea. Fennel tea is less processed and more likely to be pure; and the measurable, beneficial impacts of fennel tea suggest multiple reasons for drinking it. The U.S. Food and Drugs Administration (FDA) do not monitor supplements and extracts of herbs.

Also, some people simply find fennel tea delicious.

Studies on fennel benefits

Fennel on a wooden table, with a small bottle of fennel oil and some seed in a larger jar.
The essential oils derived from fennel seeds have a range of potentially beneficial properties.

Although most of the health claims made for fennel and fennel tea are based on traditional medicine, some scientific, medical studies have identified specific drug-like qualities of the plant, particularly its essential oils, which may promote health.

Studies have found that fennel tea benefits linked to fennel’s essential oils include:

  • reducing the formation of blood clots
  • increasing milk secretion and supporting the female reproductive system
  • acting as an antioxidant
  • antibacterial effects
  • antifungal activity
  • anti-inflammatory properties
  • anti-diabetic
  • controlling dust mites

Researchers found that ground fennel seeds in solution were effective against bacteria that cause indigestion, diarrhea, and dysentery, as well as some hospital-acquired infections.

According to one study, fennel was effective at collecting free radicals, which cause disease. This suggested fennel extracts could be used to help individuals ward off the effects of many chronic diseases and dangerous health conditions, including cancer, hardening of the arteries or atherosclerosis, and inflammation.

While even the most committed natural care providers are not claiming that drinking a cup of fennel tea could be like taking a dip in the Fountain of Youth, this research suggests that the compounds found in fennel could help buffer the effects of ageing.

Who should avoid fennel tea?

Fennel is considered fairly mild, although some people may be allergic to it. It is also possible to overdose on the extracted oils found in fennel.

Some studies have found that fennel has an estrogenic effect, which means that it mimics the effects of estrogen. Pregnant and breastfeeding women should not drink fennel tea. People with cancers that are sensitive to estrogen should also avoid the use of fennel.

Estragole, a key element in fennel, has been identified as a potential carcinogen, so individuals with cancer, or at a high-risk for the disease, are urged to limit their use of fennel tea, or avoid it altogether.