This thorn less shrub belongs to the red currant family. The leaves and berries are used medicinally. In European folk medicine, black currant once had a considerable reputation for controlling diarrhea, promoting urine output (as a diuretic) and reducing arthritic and rheumatic pains. Black currant oil is a source of gamma-linoleic acid (GLA) to treat a wide range of ailments.

Factors such as high cholesterol, aging, stress, alcohol, diabetes, premenstrual syndrome (PMS), aging, viral infections, and other conditions may interfere with the normal conversion of linoleic acid into GLA. Thus, people who obtain little GLA from their diet and those whose systems are unable to metabolize linoleic acid into GLA may benefit from taking GLA-rich supplements like black currant seed oil. According to a study published in February 2000 by researchers at Tufts University in Boston, 4.5 gm daily of black currant seed oil was able to promote cell-mediated immune function. In addition, a similar study found that black currant seed oil had an immune-enhancing effect attributable to its ability to reduce prostaglandin E (2) production. Other studies have found that the extract has anti-inflammatory properties due to its capability of stimulating the production of prostaglandin-1, an anti-inflammatory hormone.

A daily dosage of 600 to 6,000 milligrams is typical. Capsules containing black currant oil are available in 200 to 400 milligram doses - the capsules typically have a fixed oil component, and usually contain 14 to 19% GLA.

No side effects have been reported, however German health authorities warn that people with fluid accumulation, because of heart or kidney problems, should not take the leaf preparations. It should be noted, that no studies appear to have been done to determine the safety of black currant seed extract over the long term, although preliminary findings for other GLA-rich oils suggest that the supplements are relatively safe.