Omega-3 fatty acids are polyunsaturated fatty acids found in certain fish tissues, and also in some vegetable foods such as flax seeds and green leaves.
Omega-3 fatty acids are classed as essential fatty acids. These fatty acids were originally designated as "Vitamin F", until it was realized that they must be classified with the fats. The essential omega-3 fatty acid that the body cannot manufacture is EPA, eicosapentaenoic acid.
The term "omega-3" signifies that the first double bond in the carbon backbone of the fatty acid, counting from the end opposite the acid group, occurs in the third carbon-carbon bond.
Common omega-3 fatty acids in the body are linolenic acid (18:3), eicosapentaenoic acid (20:5), docosahexaenoic acid (22:6).
It has been conjectured that the diet in the Human Environment of Evolutionary Adaptedness may have been rich in seafood, and that modern diets are deficient in the ratio of Omega-3 to Omega-6 fatty acids, perhaps leading to a number of modern illnesses.
Omega-3 fatty acids are important precursors of anti-inflammatory prostaglandins.
A number of remarkable benefits have been attributed to omega-3 fatty acids in recent years. However, these are so far provisional results, and cannot yet be regarded as fact until they have been confirmed by further studies.
In its letter entitled Letter Regarding Dietary Supplement Health Claim for Omega-3 Fatty Acids and Coronary Heart Diseasethe U. S. Food and Drug Administration Center for Food Safety and Applied Nutrition, Office of Nutritional Products, Labeling, and Dietary Supplements noted that the known or suspected risks of omega-3 fatty acids may include:
In addition, another potential risk is the possibility of vitamin poisoning from taking large doses of supplements which contain Omega-3 fatty acids in addition to other dietary substances.