Mercury

Fish is often highly-recommended as a source of healthy fats and complete proteins. However, as you might have imagined, it should not be consumed every day. Fish and shellfish contain mercury, often in the form of methyl mercury, which is actually toxic for our bodies. Taking in excess amounts of fish (and therefore mercury) could be very detrimental to one’s health.

Minamata disease is a neurological syndrome caused by an excessive intake of mercury. It was discovered in the 1950’s in Japan, when over 2,000 people died, along with many of the local animals, after showing symptoms including numbness, muscle weakness, insanity, and paralysis. The cause of this was discovered to be a nearby chemical plant, which had been using methylmercury as a catalyst in their production. The fish in Minamata Bay were consequently loaded with mercury, and the locals took it in when they ate the fish.

Luckily, we do not have to worry about such extreme amounts of mercury anymore, though most fish and shellfish still contain traces of mercury, some more than others. The FDA has decided that the typical amount of mercury found in all fish and shellfish is not a health concern for the general population with the exception of a few groups: women who may become pregnant, pregnant women, nursing women, and young children. For these groups, it is recommended that the selection of fish be a bit more careful, opting for kinds that are less likely to contain high amounts of mercury. Specifically, anyone in those four groups should not eat shark, swordfish, king mackerel, or tilefish. (Notice that they all sit at the top of the food chain in the ocean, accumulating high amounts of mercury when consuming other fish.) Other kinds are acceptable, but no more than 12 ounces (or 2 average meals) should be consumed per week, because high mercury levels may harm an unborn child or young child’s nervous system.

However, fish is, on the whole, an extremely healthy choice as the “meat” for a well-balanced meal. Unless a person falls under one of the aforementioned categories, he or she should feel safe including fish as part of a normal, healthy diet.