Omega-3 fatty acids are essential fatty acids that must be supplied in the diet. They are part of the fat in food that is consumed from a balanced diet. For the infant, the essential omega-3 fatty acid is docosahexaenoic acid (DHA), which is in mother’s milk, supplemented in infant formula, and in oily fish. DHA is essential for proper brain and eye development. The DHA requirements for newborns, infants, and children were established based on years of research that showed a role for DHA in the development and functioning of the retina of the eye for vision and in the brain for learning.
Throughout life, the omega-3 fatty acids are important to support health and likely to reduce risk of chronic disease. The biological and physiological effects of dietary lipids on human health remain a primary focus of nutrition research as recommendations for daily intake are continually updated in response to new information obtained through epidemiological, clinical, and animal investigations. The role of omega-3 fatty acids in the development of the infant nervous system and retina is clearly established. In the adult, significant evidence supports a therapeutic effect of omega-3 fatty acids, both DHA and eicosapentaenoic acid (EPA) found in oily fish, on reducing factors associated with cardiovascular disease risk and in lowering blood triglycerides levels.
The actions of omega-3 fatty acids on biology to improve health and reduce chronic disease risk in human pathologies focus on biochemical and molecular targets. One area of health promotion where omega-3 fatty acids offer some advantage is in the control of chronic inflammation. Some clinical evidence suggests that omega-3 fatty acids afford benefits by lessening the severity and minimizing symptoms of chronic inflammatory diseases associated with rheumatoid arthritis and perhaps inflammatory bowel disease.
An emerging area of clinical study with adults and omega-3 fatty acids is mood and mental health. Omega-3 fatty acid dietary status determined from blood analysis and the consumption of seafood is believed to be associated with mood and mental health. The relationship between omega-3 fatty acids and psychological disorders is a complex area of research, but it is a promising opportunity for clinical investigation to improve the human condition.
The new report for dietary reference intakes (DRI) provides the first comprehensive recommendations for omega-3 fatty acids in the United States. The DRI for omega-3 fatty acids place a primary emphasis on adequate consumption of alpha-linolenic acid (ALA, 18:3n-3) to satisfy the principle requirement for all ages and both genders. To a lesser extent, provisions for modest recommended intakes are made for the long-chain omega-3 fatty acids, EPA and DHA. The daily adequate intakes for ALA are 1.6 and 1.1 g/d for adult men and women, respectively. The acceptable macronutrient distribution range (AMDR) for ALA is 0.6 to 1.2 % of daily energy intake. Both EPA and DHA can satisfy 10% of the AMDR (0.06 to 0.12% energy) for omega-3 fatty acids, and an optimal ratio of linoleic acid/ALA (n-6/n-3 fatty acids) is proposed to range from 5 to 10. Several groups of scientists are evaluating the dietary requirements for DHA and EPA, which have greater biological activity compared to ALA. Another publication called “The Dietary Guidelines for Americans”, published in 2005, provides additional information on dietary omega-3 intakes and lifestyle factors to promote health.