The aim of the present study was to investigate the effects of a moderate dose of long-chain (LC) n-3 PUFA (2.3 g EPA+DHA/d; 6:1) in the form of fish oil capsules on cardiovascular risk factors, particularly the plasma lipid profile and plasma inflammatory markers (C-reactive protein, IL-6, soluble adhesion molecules). In a double-blind placebo-controlled study twenty healthy middle-aged men were randomised to fish oil providing 2.3 g/d EPA+DHA or medium-chain TAG-rich oil (placebo) for 8 weeks. Blood was collected after an overnight fast.
Plasma total cholesterol (TC) concentration was significantly increased in the fish oil group but HDL-cholesterol and LDL-cholesterol concentrations were not significantly affected following supplementation with fish oil, although they were influenced by the placebo oil (see Table). Fish oil supplementation did not exhibit a favourable TAG-lowering effect previously shown(Reference Harris1). Likewise, positive effects of LC n-3 PUFA on inflammatory markers were not observed, except that there was a significant difference between fish oil and placebo in terms of percentage change from baseline for soluble intercellular adhesion molecule 1 (sICAM-1; P=0.05). It was demonstrated that in the fish oil group plasma sICAM-1 concentration decreased by 9.5% compared with a 9.9% increase in the placebo group. Correlation analyses, however, did not show any relationships between the changes in the fatty acid profiles, particularly of LC n-3 PUFA, and the reduction in sICAM-1.
The results of the current study are consistent with a limited effect of modest doses of LC n-3 PUFA on the outcomes studied here. Reasons for the lack of TAG lowering by fish oil may be too low an intake of LC n-3 PUFA, insufficient DHA or the inclusion of subjects who were normotriacylglycerolaemic. The finding of the current study in relation to sICAM-1 is in general accordance with some previous studies(Reference De Caterina, Liao and Libby2–Reference Hjerkinn, Seljeflot, Ellingsen, Berstad, Hjermann, Sandvik and Arnesen5) and it can be concluded that some aspects of the inflammatory response are sensitive to modest-dose LC n-3 PUFA and that EPA+DHA may exert similar modest anti-inflammatory effects in middle-aged men and in the elderly. In summary, findings from the present study indicate that a dose of 2.3 g/d EPA+DHA is not sufficient to demonstrate maximal effects on CVD risk factors, including inflammatory markers, in fairly-healthy middle-aged men.
