Essential fatty acids and modern lifestyle: a reappraisal

Controversy surrounds the effects of dietary fish oil supplementation on atherosclerosis. Three studies were undertaken, where Vervet monkeys were fed either a Western atherogenic diet (WAD) or a high carbohydrate diet (HCD). The first study indicated that enhanced atherosclerosis may be the result of an imbalance of fatty acids in plasma and tissue lipids as eicosapentaenoic acid (EPA; C20:5 ω3) was increased with fish oil (FO) supplementation at the expense of arachidonic acid (AA; C20:4 ω6). The second study investigated the effect of diet on the metabolism of EPA. Disappearance of EPA, after EPA loading, was delayed in Vervets on the WAD in comparison with those on the HCD. Results of this study indicate that diet is able to modulate EPA metabolism, and that the beneficial effects of a HCD on plasma lipoprotein concentrations can be augmented by EPA supplementation. The third study investigated the combined effect of a supplement that contained different ratios and dosages of gamma-linolenic acid (GLA; C18:3 ω6) and EPA during ingestion of the WAD. Based on a favourable response to plasma lipoprotein cholesterol and a phosphatidylcholine fatty acid metabolism with increases in both EPA and dihomogamma-linolenic acid (DGLA; C20:3 ω6), we conclude that a 4:1 ω6/ω3 fatty acid supplement at 200 mg/day would be the optimum supplement in our animal model. The long-term effects of this supplement on lipoprotein metabolism and atherosclerosis in the non-human primate model, is currently under investigation.