Fish is one of the world’s most eaten foods, and for most people it is their main source of animal protein. Countries such as Portugal, New Zealand, Japan, Iceland and Australia have the world’s largest per capita consumption of fish in the world. According to the Food Standards Agency people should ideally consume at least two portions of fish each week, one of those being an oil-rich type of fish such as mackerel or herring. The oil in these types of fish contains large amounts of Omega-3 type oils, a component of every cell in the human body, and crucial for proper brain functioning.

Low fat fish like haddock and cod, both types of whitefish, can be combined with oily Omega-3 fish like sardines, fresh tuna, salmon and trout, can aid in the defense against coronary heart disease, and also help strengthen bones and teeth. Shellfish, like shrimp and lobster, are high in zinc, an important element necessary for healthy skin and muscles, and also contributes to an individual’s fertility.

There are many health benefits to eating fish, but there are also some concerns. Mercury poisoning can be a problem when eating fish that are high up in the food chain. The reason for this is that shellfish and ordinary fish both have a natural tendency to concentrate mercury in their bodies. In the muscle tissue the mercury is converted to methyl mercury, which is a highly toxic organic compound of mercury. Because fish are much more adept at retaining and accumulating the mercury rather than depurating it, the mercury becomes more concentrated in their bodies over time. As larger fish eat smaller fish containing mercury, all the mercury in the smaller fish becomes assimilated into the body of the larger fish. This is a problem for the consumption of fish high on the food chain such as shark, swordfish, king mackerel, albacore tuna and tilefish.