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Black Currant Confers Immunity

Black currant seed oil stimulates immune function in older people, according to a new study by Dayong Wu, Ph.D., of Tufts University in Boston.

Lowered immunity plagues the elderly and may be partially caused by a potent chemical signaler, prostaglandin PGE-2, which interferes with T-cell function. T-cells stimulate other cellular components of the immune system to kill or neutralize invading bacteria and viruses.

In this double-blind, placebo-controlled study, 29 people older than 65 took 4.5 g daily of either black currant seed oil or soybean oil for two months.

Researchers evaluated subjects' cell-mediated immune function by measuring skin response to an antigen called tetanus toxoid. Response to the toxin generally declines with age. Subjects who took black currant seed oil showed a 28 percent greater skin response after two months. The placebo group's response was unchanged.

The group taking black currant seed oil also showed a dramatic drop in PGE-2 production not seen in those taking placebo. Black currant seed oil is one of the richest sources of gamma linolenic acid, which stimulates production of beneficial prostaglandins such as PGE-1. Such prostaglandins act in opposition to PGE-2 by reducing inflammation and possibly preventing diseases such as atherosclerosis and arthritis. Older people produce less gamma linolenic acid on their own and so may benefit from supplements. Black currant seed oil also contains stearidonic acid, another possible PGE-2 inhibitor.

There was no difference between the two groups in other immune markers such as production of interleukins and lymphocytes.

American Journal of Clinical Nutrition, 1999 Oct;70(4):536-43.