The black currant, which grows on a small, shrublike bush, has an illustrious history. Because of its rather unpleasant, astringent tartness, this pea-sized berry was never particularly popular until after World War 2. Native to the European and British Isle latitudes, the black currant earned its fame as a vitamin C substitute during the war.1

Since other foodstuffs rich in nutrients were universally commandeered for military use, this nutrient-rich berry became popular almost overnight as a means of nourishing British children. The berries were harvested and cooked down into syrup, a process that improved the sweetness and overall palatal appeal. After the war ended, however, the black currant returned to anonymity—until recently.

Background

After the black currant was brought to the United States, cultivation boomed until the early 20th century. At this time, a plant virus known as “white pine blister rust” hit America’s lumber industry. When the black currant shrub was identified as the host source, the U.S. government banned cultivation. This prohibition continued until 1966.2

More recently, however, continued research has verified black currant’s nutritive value and reinstated its value as a commercial plant. The oxygen radical absorbance capacity (ORAC) for black currant shows an impressive 10,144, compared with the blueberry at 9,245.3 ORAC measures the degree of inhibition of peroxy-radical-induced oxidation of a food per 100-g sample.3 With quadruple the vitamin C content of orange juice and an unexpected concentration of essential fatty acids and anthocyanins, black currants are being considered for their potential in treating a wide range of conditions involving inflammation.4 In some clinical trials, black currant’s efficacy is being compared with such nonsteroidal anti-inflammatory drugs as ibuprofen and aspirin.4

Science

Black currant’s effectiveness in treating rheumatoid arthritis (RA) has received a great deal of attention recently. Given that RA is an intensely inflammatory condition, studies have focused on the berry’s high content of gamma linolenic acid (GLA),5 an essential fatty acid that possesses significant anti-inflammatory properties. GLA aids in reducing and/or blocking the autoimmune-mediated generation of prostaglandins and other cytokines as well as tumor necrosis factor alpha (TNF-alpha).5 A Cochrane review of herbal therapies in RA looked at seven trials that evaluated GLA against either placebo or active controls. Of those trials meeting the review criteria, all showed significant improvement in clinical outcomes.6

The same anti-inflammatory action that aids in RA is also connected to the modulation of endothelial inflammation and platelet dysfunction.7 In this arena, the berry’s high GLA content as well as its anthocyanin-rich properties play a role. Anthocyanins are extremely efficient oxygen-free radical scavengers and are thought to be especially active in the vascular system, thus playing a very important part in the mediation of early micro- and macrovascular disease.7,8

Because of its powerful combination of antioxidant compounds, black-current concentrate is being researched for a variety of conditions whose underlying pathophysiology is either autoimmune in nature or involves oxidative inflammation. Although significant trial data are not yet available in the United States, conditions under consideration include diabetic neuropathy, cancer, certain vision impairments, and hyperlipidemia.8,9

Safety, interactions

Other than the potential for plant allergy, black currant has a very low side-effect and interaction profile. In high doses, gastric upset is possible. Because of the berry’s high antioxidant action, it can potentiate antiplatelet or other blood-thinning drugs.10 Specific safety data for infants and pregnant or nursing women is not available.

How supplied, dosage, cost

Berry juice concentrate, black currant seed oil, and capsules of dried berry powder are the main forms available in most health-food stores in the United States. Because of the lack of definitive trials and the array of forms and concentrations, no specific recommended dose has been proposed. However, the major trials reviewed used an average of 500 to 700 mg of seed oil or capsule form taken three times daily with food.10 Black currant products at the doses discussed are among the more expensive of supplements, ranging from $30 to $50 per month, depending on the strength and form.

Summary

Even without a large body of compelling research-based evidence, black-currant supplements are an intriguing and tasty addition to our supplement arsenal. Whether as a tea or other supplement, black currant has very few negatives and a large number of positives. Recommending this supplement to patients who would benefit from a potent general antioxidant is a safe and proactive step and could possibly even replace some other supplements.

References

1. Blackcurrant Facts and Nutrition Data. Black currant history. 

2. Forest and Shade Tree Pathology. White pine blister rust.

3. Agricultural Research Service. USDA database for the oxygen radical absorbance capacity (ORAC) of selected foods, release 2.

4. Cameron M, Gagnier JJ, Little CV, et al. Evidence of effectiveness of herbal medicinal products in the treatment of arthritis. Part 2: Rheumatoid arthritis. Phytother Res. 2009;23:1647-1662.

5. Darlington LG, Stone TW. Antioxidants and fatty acids in the amelioration of rheumatoid arthritis and related disorders. Br J Nutr. 2001;85:251-269.

6. Little C, Parsons T. Herbal therapy for treating rheumatoid arthritis. Cochrane Database Syst Rev. 2001;1:CD002948.

7. Natural Products Insider. Black currant—a clinical perspective.

8. Kapasakalidis PG, Rastall RA, Gordon MH. Extraction of polyphenols from processed black currant (Ribes nigrum L.) residues. J Agric Food Chem. 2006;54:4016-4021.

9. Nakaishi H, Matsumoto H, Tominaga S, Hirayama M. Effects of black currant anthocyanoside intake on dark adaptation and VDT work-induced transient refractive alteration in healthy humans. Altern Med Rev. 2000;5:553-562.

10. Drugs.com. Black currant.

All electronic documents accessed January 15, 2011.