Polyunsaturated fatty acids (PUFA): the “essential” fatty acids


Polyunsaturated fatty acids such as linoleic acid and alpha-linolenic acid (ALA) contain 2 or more cis-double bonds, causing PUFA to have very low melting points; in fact, they are liquid at room temperature. There are 2 major types of PUFA: omega-6 and omega-3 fatty acids.1 PUFA are often referred to as essential fatty acids because the human body is unable to make these de novo.1 As important precursors for a number of biologically active molecules (such as prostaglandins, leukotrienes, and thromboxanes), they must be in the diet.1


Omega-6: where it’s found
  • Relatively high amounts are found in vegetable, nut, and seed oils (eg, cottonseed oil, sunflower oil, corn oil, soybean oil)1
Effects on the body
  • Decreases total and LDL cholesterol1
  • Decreases HDL cholesterol (if replacing saturated fat or MUFA)2
  • Limited and not conclusive scientific evidence suggests that consumption of products high in unsaturated fat may reduce the risk of CHD. To achieve this benefit the unsaturated fat content should replace a similar amount of saturated fat without increasing caloric intake
  • High intake of omega-6 may increase production of proinflammatory and proaggregatory molecules3,4
Omega-3: where it's found
  • Omega-3 PUFA are much less abundant in the diet, but can be found in appreciable quantities in fish and flaxseed oils1
    • Also found in other seed and nut oils, as well as green leafy vegetables, meats, and dairy products1
Effects on the body
  • Supportive but not conclusive research shows that consumption of EPA and DHA omega-3 fatty acids may reduce the risk of CHD1
  • Decosahexaenoic acid (DHA), a long-chain omega-3 fatty acid, is an important membrane component in sperm, the cerebral cortex, and the retina4
  • DHA and eicosapentaenoic acid (EPA), another long-chain omega-3 fatty acid, promote production of less proinflammatory and proaggregatory molecules4
ADA recommended daily intake

Omega-6 PUFA: 3% to 10% energy per day. Omega-3 PUFA: 0.6% to 1.2% energy per day.1



Click here for more about Omega-3 and Omega-6

Conclusions from the literature

PUFA have a generally positive effect on blood lipids, decreasing LDL cholesterol, but also decreasing HDL cholesterol. The ratio of omega-6:omega-3 in the Amerian diet is high (approximately 10–15:1)4,5 and is best improved by increased intake of omega-3 fatty acids, rather than decreased omega-6 fatty acids.4,6


Click here to read the medical literature

References: 1. Position of the American Dietetic Association and Dietitians of Canada. Dietary fatty acids. J Am Diet Assoc. 2007;107:1599–1611. 2. Karmally W. Balancing unsaturated fatty acids: what’s the evidence for cholesterol lowering? J Am Diet Assoc. 2005;105:1068–1070. 3. Van Horn L, McCoin M, Kris-Etherton PM, et al. The evidence for dietary prevention and treatment of cardiovascular disease. J Am Diet Assoc. 2008;108:287–331. 4. Simopoulos AP. The importance of the omega-6/omega-3 fatty acid ratio in cardiovascular disease and other chronic diseases. Exp Biol Med. 2008;233:674–688. 5. Kris-Etherton PM, Taylor DS, Yu-Poth S, et al. Polyunsaturated fatty acids in the food chain in the United States. Am J Clin Nutr. 2000;71(suppl):179S–188S. 6. Harris WS, Mozaffarian D, Rimm E, et al. Omega-6 fatty acids and risk for cardiovascular disease: a science advisory from the American Heart Association Nutrition Subcommittee of the Council on Nutrition, Physical Activity, and Metabolism; Council on Cardiovascular Nursing; and Council on Epidemiology and Prevention. Circulation. 2009;119:902–907.