Omega-3 Fatty Acid Biochemistry: Perspectives from Human Nutrition

The possibility that western diets poor in omega-3 and rich in omega-6 fatty acids contribute to the increasing burden of chronic diseases including neurological problems is becoming recognized. Modern, westernized diets provide 80 to 90% of polyunsaturated fatty acids as omega-6 linoleic acid (LA) and are depleted in omega-3 fatty acids, giving a distorted balance of LA to alpha-linoleic acid, and to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). LA intakes exceed D-6 desaturase needs for maximal activity. LA accumulates in blood and tissue lipids with increasing intake, and this exacerbates competition between LA and limited omega-3 fatty acids for metabolism and acylation into tissue lipids. Increasing EPA and DHA intake decreases tissue omega-6 fatty acids while also providing EPA and DHA. However, strategies for EPA and DHA supplementation do not address potential underlying problems of omega-6 and omega-3 fatty acid imbalance in the food supply.