EPA May Decrease NK Cell Activity

OXFORD, England--In the March American Journal of Clinical Nutrition (73: 539-48, 2001), it was found that eicosapentaenoic acid (EPA) supplementation may decrease natural killer (NK) cell activity in healthy individuals. In a randomized, placebo-controlled, double-blind parallel study, healthy men and women between 55 and 75 years old consumed either a placebo or one of two oil mixtures. The first oil mixture combined 2 g of flaxseed oil (ALA-rich), 220 mg of evening primrose oil (GLA-rich), 680 mg of arachidonic acid (AA) and 720 mg of docosahexaenoic acids (DHA); the second mixture contained fish oils (720mg of EPA and 280 mg of DHA). Researchers, led by Frank Thies of the University of Oxford, found that the fish oil supplementation alone significantly reduced NK cell activity with a mean decrease of 48 percent. The study's authors concluded that a moderate amount of EPA, but not other omega-3 or omega-6 polyunsaturated fats, may reduce NK activity in healthy people. "The effects of EPA on the immune system are the result of several mechanisms," said Morten Brynn, M.D., vice president of research and development at Pronova Biocare. "The effect on NK cells is only one mechanism." For more on the study, visit www.ajcn.org.