Effect of a low fat diet on essential fatty acid metabolism in healthy human subjects.

The fatty acid pattern in phospholipids of serum and platelets, and conversion of labelled 18:3(n-3) and 20:3(n-6) in cultured lymphocytes was studied in healthy subjects consuming a low fat diet for four weeks. In serum and platelets the level of polyunsaturated C20 and C22 fatty acids was maintained stable, while the content of 18:2(n-6) was significantly decreased. The delta 6-desaturase activity in lymphocytes was increased after the low fat diet, while the rate of delta 5-desaturation was unchanged. It is concluded that the rate of delta 6-desaturation and perhaps also chain-elongation is regulated by the content and composition of dietary lipids in order to maintain the fatty acid pattern of phospholipids stable.