NO EFFECTS ON INSULIN SENSITIVITY BUT DIVERGING EFFECTS ON SERUM-FREEFATTY-ACID CONCENTRATIONS BY ADDITION OF SEAFOOD PRODUCTS CONTAINING EITHER N-3 OR N-6 FATTY-ACIDS

Background and Aim: To evaluate the metabolic effects of a diet that i ncludes seafood fortified with n-3 fatty acids, and its effects on ins ulin sensitivity. Methods and Results: In a double blind cross over st udy conducted during two 4-week periods, thirteen healthy subjects wit h a mean age of 47.5+/-7 years were given seafood products fortified w ith fish oil containing 2 g long chain n-3 fatty acids daily or the co rresponding amount of sunflower oil during the control period. Very lo w density lipoprotein (VLDL) levels decreased by about 40% (p<0.001) o n both diet periods and fasting insulin concentration decreased by 22- 24% (p<0.05), No effects were seen on blood pressure or peripheral ins ulin sensitivity on either diet, but there was a pronounced reduction of the concentration of free fatty acids [-31%, (p<0.001) during the s upplementation of seafood products with long chain n-3 fatty acids, si gnificantly more than during the control period (-6%, p<0.05)]. Enrich ment of fish oil containing seafood products with a tocopherol and asc orbic acid caused a marked increase in serum a tocopherol concentratio n, which seemed to protect lipids from oxidation, as the plasma malond ialdehyde concentration was unchanged. Conclusions: Enrichment of seaf ood products is also a natural and easy way to ensure an optimal intak e of long chain n-3 fatty acids, also in people who do not eat natural fish. A daily supplementation of seafood products with 2 g of n-3 fat ty acids, compared to a control period when sunflower oil was suppleme nted, caused a pronounced reduction of serum free fatty acids but did not affect blood pressure or peripheral insulin sensitivity when admin istered during a four-week period to healthy subjects. (C) 1998, Medik al Press.