Omega−3 fatty acids, are polyunsaturated fatty acids. This means that they are defined by the presence of a double bond three atoms away from the terminal methyl group in their chemical structure.
Omega-3 fatty acids are common in the natural world. They are very important constituents of animal lipid metabolism, and they play an important role in the human diet and in human physiology.
The three types of omega−3 fatty acids involved in human physiology are α-linolenic acid (ALA), found in plant oils, and 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 ALA 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 fatty acids EPA and DHA include fish, fish oils, eggs from chickens fed EPA and DHA, squid oils, krill oil, and certain algae.
Mammals such as humans are unable to synthesize the essential omega−3 fatty acid ALA and can only obtain it through diet.
Omega-3 fatty acids play an integral role in cancer prevention.