Omega-3 fatty acids are substances included in the group of polyunsaturated fatty acids, as well as essential fatty acids (EFAs), which contain a double bond at the third carbon atom counting from the methyl end of the chain. This group includes compounds such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Omega-3s are not synthesized in the human body, so they must be supplied to the system from the outside - with the daily menu or in the form of dietary supplements. The sources of omega-3 fatty acids are primarily oily marine fish, as well as seafood and caviar.