They are polyunsaturated fatty acids (PUFA) with a double bond (C = C) at the third carbon atom from the end of the carbon Chain. Fatty acids have two ends, the carboxylic end (-COOH), which is considered the beginning of the chain, therefore "alpha", and the methyl end (-CH3), which is considered the "tail" of the chain., Therefore "omega"; The double bond is in omega minus 3 (not the dash 3). One way a fatty acid is named is determined by the location of the first double bond, counted from the methyl end, that is, the omega (ω-) or the n- end. However, the standard chemical nomenclature system (IUPAC) starts from the carbonyl end.
The three types of omega-3 fatty acids involved in human physiology are α-linolenic acid (ALA) (found in vegetable oils), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). The algae and marine phytoplankton are primary sources of omega-3 fatty acids. Common sources of vegetable oils that contain the omega-3 fatty acid ALA include walnut, edible seeds, clary clay seed oil, seaweed oil, linseed oil, Sacha Inchi oil, Echium oil, and hemp oil, while the sources of animal omega-3 EPA and DHA fatty acids include fish, fish oils, chicken eggs fed EPA and DHA, squid oils and krill oil. Dietary supplementation with omega-3 fatty acids does not appear to affect the risk of death, cancer, or heart disease. Additionally, studies of fish oil supplements have failed to support claims of heart attack or stroke prevention.
Omega-3 fatty acids are important for normal metabolism. Mammals are unable to synthesize omega-3 fatty acids, but they can obtain the short-chain ALA of omega-3 fatty acids (18 carbons and 3 double bonds) through the diet and use it to form omega-3 fatty acids from more important long chain, EPA (20 carbons and 5 double bonds) and after EPA, the most crucial, DHA (22 carbons and 6 double bonds). The ability to produce the long-chain omega-3 fatty acids from ALA can be impaired in aging.
