An assessment of docosahexaenoic acid (DHA) intake with special reference to lipid metabolism in rats.

In order to determine the appropriate intake of docosahexaenoic acid (22:6n-3, DHA), the potential changes in lipid peroxidation and antioxidant defense in serum and tissue as well as the changes in serum lipid levels were examined in rats by giving them diets containing graded levels of purified DHA (0, 1.0, 3.4 and 8.7 energy % in the diets) for 2 weeks. Serum alpha-tocopherol concentration decreased slightly but significantly even at the 1.0 energy %. Liver lipid peroxide levels as assessed by the thiobarbituric acid (TBA) value and chemiluminescence intensity augmented at the 3.4 energy % and more, and the alpha-tocopherol content significantly decreased in response to the increase in lipid peroxide levels. In the kidney, a slight but significant increase in TBA value was observed even at 1.0 energy % and higher. All the serum lipid levels as analyzed by total cholesterol, HDL-cholesterol, triacylglycerol (TG) and phospholipids (PLs) decreased as the dietary DHA level increased. These experimental results suggest that the dietary intake of DHA should be less than 1 energy % to avoid promoting deleterious influences such as serum and tissue lipid peroxidation and to ameliorate serum lipid levels.