Fish is a food consumed by many species, including humans. The word "fish" refers to both the animal and to the food prepared from it. Fish has been an important source of protein for humans throughout recorded history. Fish, especially saltwater fish, is high in omega 3 fatty acids, which are heart-friendly, and a regular diet of fish is highly recommended by nutritionists. This is conjectured to be one of the major causes of reduced risk for cardiovascular diseases in Eskimos. It has been suggested that the longer lifespan of Japanese and Nordic populations may be partially due to their higher consumption of fish and seafood. The Mediterranean diet is likewise based on a rich intake of fish. Nutritionists recommend that fish be eaten at least 2-3 times a week.