Review of Black Cumin for Metabolic Disorders

Black cumin (Nigella sativa, Ranunculaceae) seed is popular in the Middle East and Southeast Asia for treating diabetes, dyslipidemia, hypertension, and obesity. However, clinical evidence is inconclusive. The purpose of this systematic review was to evaluate the clinical and biochemical effects of black cumin on lipid profiles, glycemic factors, blood pressure, and anthropometric indices (weight, body mass index [BMI], and waist circumference), all of which are parameters of metabolic syndrome.

The following databases were searched from inception through June 2014: PubMed, Google Scholar, Thomson Reuters Web of Science, and Cochrane. The following medical subject headings (MeSH) and title/abstract (tiab) search terms were used: (“Nigella sativa” [MeSH] OR “black seed” [tiab] OR “black cumin” [tiab] OR “Kalonji” [tiab]) AND “Triglycerides” [MeSH] OR “Cholesterol” [MeSH] OR “Lipoproteins, LDL” [MeSH] OR “Lipoproteins, HDL” [MeSH] OR “Blood glucose” [MeSH] OR “Hemoglobin A, Glycosylated” [MeSH] OR “Blood pressure” [MeSH] OR “Body mass index” [MeSH] OR “Waist circumference” [MeSH]). The inclusion criteria were (1) published in English, (2) the effect of black cumin on clinical or biochemical parameters, and (3) clinical trial. The exclusion criteria were (1) animal studies, (2) review studies, (3) the effect of black cumin on unrelated blood or clinical parameters, (4) the effect of black cumin combined with other plants or exercise, and (5) duplicated studies.

A total of 515 articles were located, and 18 studies (with a total of 1531 subjects) met the inclusion/exclusion criteria. The studies were highly heterogeneous: five studies were randomized, double-blind, controlled studies; five studies had no control group, and eight studies were randomized controlled studies. Included patients were aged 18-65 years and had diabetes (n = 5 studies), metabolic syndrome (n = 7 studies), hyperlipidemia (n = 4 studies), hypertension/coronary disease (n = 2 studies), obesity (n = 1 study), or were healthy subjects (n = 4 studies). All treatments were oral and doses ranged from 200 mg/day to 5 g/day of seed extract (n = 2 studies), seed oil (n = 8 studies), or seed powder (n = 13 studies). Treatment duration ranged from two weeks to six months.

Table 1 summarizes the study findings. The authors note significant findings; however, they do not report whether the changes are compared with baseline or control. In Table 1, the column titled “overall effect” indicates which parameters had more evidence in favor of a significant improvement.

Table 1: Summary of Number of Studies with Significant Improvements in Measured Parameters

Number of Studies
Parameters Significant improvement No significant effect Overall effect (Yes/No)
Triglycerides 7 10 No
Total cholesterol 10 4 Yes
Low-density lipoprotein (LDL) cholesterol 11 3 Yes
High-density lipoprotein (HDL) cholesterol 6 10 No
Fasting blood sugar 13 3 Yes
Glycosylated hemoglobin 4 Yes
Blood pressure 4 5 No
Weight 2 6 No
BMI 2 6 No
Waist circumference 1 5 No

Based on the number of studies demonstrating a significant improvement, the evidence weighs more in favor of black cumin improving total cholesterol, LDL, fasting blood sugar, and glycosylated hemoglobin. Evidence does not support an effect of black cumin on blood pressure or anthropometric indices. A total of 10 studies evaluated safety. Two studies that treated subjects with 5 mL/day black cumin seed oil reported mild nausea that resolved after one week of treatment. Eight studies measured liver and kidney function and reported no adverse effects.

The authors conclude that black cumin should be “a complementary treatment protocol for many diseases, especially metabolic disorders.” However, even though the evidence leans more favorably in the direction of a benefit for some parameters, the heterogeneity of the studies must be taken into consideration. It would have been advantageous if the researchers conducted a meta-analysis to provide more scientific rigor to their analysis and conclusions. Recommendations for the effective dose or preparation cannot be gleaned from this analysis. More research is needed if black cumin is to be recommended as a treatment for patients with symptoms of metabolic syndrome.


Mohtashami A, Entezari MH. Effects of Nigella sativa supplementation on blood parameters and anthropometric indices in adults: A systematic review of clinical trials. J Res Med Sci. 2016;21:3. doi: 10.4103/1735-1995.175154.



Black Chokeberry—Bioactivities of Phenolic-rich Fruit May Contribute to Prevention of Chronic Diseases

Bioactive plant-derived compounds, especially phenolics with high antioxidant activity, are increasingly shown to be beneficial in preventing and treating chronic diseases. Black chokeberry (Aronia melanocarpa, Rosaceae) fruit has high levels of antioxidants, especially anthocyanins in the form of cyanidin derivatives. Black chokeberry fruit also contains other beneficial compounds such as vitamins C and E, carotenoids, pectins, and organic acids, as well as essential minerals (potassium, calcium, and magnesium).

Black chokeberry is native to eastern North America, from the Great Lakes to New England and higher altitudes of the Appalachians. Its fruits were used by Native Americans to treat colds. Introduced to Russia in the early 1900s, black chokeberry soon spread throughout the country, and in the early 20th century was introduced to other European nations, especially in Eastern Europe and Scandinavia. Several cultivars with larger and sweeter fruit have been developed in Northern and Eastern Europe, of which two, “Viking” and “Nero,” are available in the United States. A high tannin level and astringent taste limit black chokeberry’s popularity as a fresh fruit. It is widely used as a food colorant and flavoring; in teas (infusions), juices, jams, purees, etc.; and as a source of compounds for nutritional supplements. Its pomace is rich in bio-actives.

The authors summarize black chokeberry fruit’s composition and the bioavailability, antioxidant properties, and health-promoting benefits of its compounds in relation to chronic diseases. They do not describe search methods for the information presented.

Polyphenols are the major bioactive compounds of black chokeberry. These dietary antioxidants can scavenge free radicals, a cause of oxidative stress, which causes chronic inflammation and thereby increases the risk of diseases including atherosclerosis, cancer, and neurodegenerative conditions. Black chokeberry fruit’s total phenolic (TP) content is in the range of 690-2560 mg gallic acid equivalents (GAE) per 100 g fresh weight. This is higher than for many better-known berry crops, including blueberry (Vaccinium spp., Ericaceae), red raspberry (Rubus idaeus, Rosaceae), red currant (Ribes rubrum, Grossulariaceae), strawberry (Fragaria × ananassa, Rosaceae), “blackberry” (Rubus fruticosus; also a generic common name for an edible fruit produced by many Rubus spp.), and cranberry (V. macrocarpon), and comparable to the TP content of bilberry (V. myrtillus) and hawthorn (Crataegus monogyna, Rosaceae) fruit. As in other phenolic-producing plants, black chokeberry’s TP content and levels of specific phenolic compounds vary with cultivar and genotype, growth conditions, maturity at harvest, extraction and/or processing methods, and storage. The highest levels of phenolic compounds are found in the “Hugist” cultivar; the lowest, in “Aron.” The average concentration of phenolics in pomace is about five times that in black chokeberry juice. The most important phenolic compounds in black chokeberry fruits are phenolic acids, especially hydroxycinnamic acids, and flavonoids, including flavonols (epicatechin), flavonols (mainly quercetin glycosides), anthocyanins, and proanthocyanidins. While intestinal absorption of black chokeberry polyphenols is very poor, metabolization into other compounds allows for their beneficial effects. Quantities and proportions of individual phenolics vary among cultivars and plant parts and are affected by extraction/processing and storage methods. The relative antioxidant activities of different extracts and products are detailed. Compared with black chokeberry cultivars “Viking” and “Aron,” purple chokeberry (Aronia × prunifolia) dried berries had higher antioxidant activity. It is noted that black chokeberry’s lipophilic antioxidant capacity is quite low. It’s hydrophilic antioxidant capacity, along with black currant (Ribes nigrum) and elderberry (Sambucus spp., Adoxaceae), is among the highest of berry fruits.

Black chokeberry exerts anti-inflammatory, anti-atherosclerotic, hypotensive, anticoagulant, antithrombotic, and antiplatelet activities, making it especially valuable for cardiovascular health. It also has immunomodulatory, antiviral, and antibacterial effects. Black chokeberry extract decreases the expression of genes for cholesterol synthesis, uptake, and efflux dose-dependently in humans. It is known for its gastroprotective effects, especially against peptic ulcer, and for its antidiabetic effects, improving fasting glucose and lipid profiles. Anthocyanins may help prevent obesity and, by inhibiting α-glucosidase and α-amylase activities, reduce postprandial hyperglycemia. Aronia spp. extracts benefit risk factors related to insulin resistance, modulating multiple associated pathways. Black chokeberry anthocyanins can normalize carbohydrate metabolism. The anticancer effects of black chokeberry also operate through numerous pathways and mechanisms, including induction of detoxication enzymes, induction of cell cycle arrest apoptosis, and changes in cellular signaling. In vitro, it retards or halts the growth of human breast, leukemia, colon, and cervical cancer lines. Black chokeberry may reduce oxidative stress in patients with cancer before and after surgery. Different extracts and polyphenolic compounds may affect different cancer cell lines more or less strongly. Overall, black chokeberry, like other less-utilized berry crops, offers many positive benefits for prevention and treatment of chronic diseases. While some human trials are mentioned, more research is clearly warranted.


Jurikova T, Mlcek J, Skrovankova S, et al. Fruits of black chokeberry Aronia melanocarpa in the prevention of chronic diseases. Molecules. June 7, 2017;22(6):944. doi: 10.3390/molecules22060944.