Oxidized fish oil in supplement capsules may contain lower levels of EPA and DHA. Light, oxygen exposure, and heat can all contribute to oxidation of fish oil supplements. Buying a quality product that is kept cold in storage and then keeping it in a refrigerator can help minimize oxidation. Hypothesized role in human evolution An abundance of DHA in seafood has been suggested as being helpful in the development of a large brain, though other researchers claim a terrestrial diet could also have provided the necessary DHA. See also DHA-clozapine List of omega-3 fatty acids Polyunsaturated fatty acids References Fatty acids Alkenoic acids Polyenes