What are omega-3 fatty acids?

It is known that fish and shellfish are an important part of the Mediterranean diet, they are a source of vitamins, minerals, proteins and also fatty acids. The latter have been gaining interest for being beneficial to human health and numerous studies have been carried out showing that long-term and regular consumption of fish reduces the risk of some diseases (such as cancer, Alzheimer's and cardiovascular diseases)

Omega-3 fatty acids are a type of lipid from the fatty acid family that the human body cannot synthesize and therefore must be incorporated through the diet. They are found in marine species in the form, mainly, of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), and also in some terrestrial vegetables (such as soybeans, olives, flaxseed and walnuts) in the form of linolenic acid (ALA).

All marine animals have omega-3, although not in the same proportion. If you want to find more information, http://www.oceanshealth.udg.edu/ca/que-son-els-acids-grassos-omega-3-i-on-es-tro.html