Positive Health Online

Abstract

HWANG and colleagues, Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, USA HWANGDH@MHS.PBRC.EDU write that contradictory reports regarding protective effect of fish consumption upon risk of cardiovascular disease (CVD) may be due to variations in n-3 and n-6 polyunsaturated fatty acid (PUFAs) intakes. @m: Competition metabolically between n-3 and n-6 PUFAs raises the possibility that vegetable n-6 PUFAs could attenuate the efficacy of fish oil n-3 PUFAs and favourably change endpoints relevant to CVD risk. The authors determined effects of varying amounts of dietary fish oil upon lipid and thrombotic endpoints relevant to CVD risk factors and studied whether these effects were attenuated by vegetable oils. The authors conducted 2 randomised double-blind, placebo-controlled studies in people who took varying amounts of n-3 and n-6 PUFAs. Intake of n-3 PUFA was varied using fish or placebo oil capsules, that of 6-6 PUFA modified by incorporating varying amounts of safflower oil into the diet. Endpoints included changes in membrane fatty acid composition, blood lipids, and thrombotic profile. @r:RESULTS: The results demonstrated that absolute amounts of fish oil, not relative amounts of fish and vegetable oil - ratios of n-3 to n-6 PUFAs determined the size of reduction of arachidonic acid and increase in eicosapentaenoic acid in phospholipids of plasma and platelets. Suppression of plasma triacylglycerols by fish oil was not changed by varying the amounts of dietary n-6 PUFAs. Fibrinogen levels decreased with 15 g but not with 9 g fish oil per day at the same ratio of n-3 to n-6 PUFAs. @c:CONCLUSIONS: Efficacy of fish oil in favourably modifying certain risk factors for CVD was not attenuated by vegetable oil.

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Hwang DH et al. Does vegetable oil attenuate the beneficial effects of fish oil in reducing risk factors for cardiovascular disease? Am J Clin Nutr 66(1): 89-96. July 1997.