PROINFLAMMATORY AND ANTIINFLAMMATORY CYTOKINES IN HEALTHY-VOLUNTEERS FED VARIOUS DOSES OF FISH-OIL FOR 1 YEAR

Dietary supplementation with n-3 fatty acids from fish oil alleviates inflammation in various chronic inflammatory disease states. Reduction s in the production of pro-inflammatory cytokines interleukin 1 beta ( IL-1 beta), tumour necrosis factor alpha (TNF-alpha), and interleukin 6 (IL-6) have been seen in humans after short-term n-3 fatty acid supp lementation. We investigated longterm effects of dietary n-3 fatty aci ds on circulating cytokine concentrations and on ex vivo stimulated wh ole-blood production of IL-1 beta, TNF-alpha and interleukin 1 recepto r antagonist (IL-1Ra), the naturally occurring antagonist of IL-1. A t otal of 58 monks with a mean age of 56 years were randomized into four groups and their diets were supplemented with 0, 3, 6, or 9 g of fish oil, providing 0, 1.06, 2.13 or 3.19 g of n-3 fatty acids per day. Su bjects received equal amounts of saturated fatty acids, vitamin E and cholesterol. Compliance was excellent and erythrocyte fatty acid profi les closely reflected the amounts of n-3 fatty acids ingested. In the group receiving 9 g of fish oil per day, no influence of n-3 fatty aci ds on circulating cytokine concentrations was observed relative to pla cebo. Endotoxin-stimulated whole-blood cytokine production was measure d at 26 and 52 weeks after the start and at 4, 8 and 26 weeks after ce ssation of supplementation. In all groups, the production of IL-1 beta and IL-1Ra was higher during supplementation than afterwards. However , no differences in cytokine production were noted between the placebo group and the various treatment groups at any point in time. Our resu lts suggest that long-term supplementation of fish oil does not affect ex vivo cytokine production in man.