<Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> <P> Omega - 3 fatty acids--also called ω - 3 fatty acids or n - 3 fatty acids--are polyunsaturated fatty acids (PUFAs) with a double bond (C = C) at the third carbon atom from the end of the carbon chain . The fatty acids have two ends, the carboxylic acid (- COOH) end, which is considered the beginning of the chain, thus "alpha", and the methyl (- CH) end, which is considered the "tail" of the chain, thus "omega"; the double bond is at omega minus 3 (not dash 3). One way in which 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 (IUPAC) chemical nomenclature system starts from the carbonyl end . </P> <P> The three types of omega - 3 fatty acids involved in human physiology are α - linolenic acid (ALA) (found in plant oils), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) (both commonly found in marine oils). Marine algae and phytoplankton are primary sources of omega - 3 fatty acids . Common sources of plant oils containing the omega - 3 ALA fatty acid include walnut, edible seeds, clary sage seed oil, algal oil, flaxseed oil, Sacha Inchi oil, Echium oil, and hemp oil, while sources of animal omega - 3 EPA and DHA fatty acids include fish, fish oils, eggs from chickens 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 . Furthermore, fish oil supplement studies have failed to support claims of preventing heart attacks or strokes . </P> <P> Omega - 3 fatty acids are important for normal metabolism . Mammals are unable to synthesize omega - 3 fatty acids, but can obtain the shorter - chain omega - 3 fatty acid ALA (18 carbons and 3 double bonds) through diet and use it to form the more important long - chain omega - 3 fatty acids, EPA (20 carbons and 5 double bonds) and then from EPA, the most crucial, DHA (22 carbons and 6 double bonds). The ability to make the longer - chain omega - 3 fatty acids from ALA may be impaired in aging . In foods exposed to air, unsaturated fatty acids are vulnerable to oxidation and rancidity . </P>

What are the different types of omega 3 fatty acids
find me the text answering this question