Benefits and risks of eating fish
Fish are an excellent source of protein. It is also the most significant source of essential fatty acids, like omega-3 fatty acid, which improves heart, reduces cholesterol, and can even have positive impact on mood. The traditional diet of some of the most long-living peoples in our planet is based on fish.
However, this does not mean that all fish is good and that it can be eaten with no precautions whatsoever. Unfortunately, some kinds of fish contain mercury, a heavy metal that can be poisonous.
Mercury in fish
Mercury is present in small concentrations in sea water. It is absorbed by algae at the beginning of the food chain. Then it is consumed by the fish that eat algae and the chain continues with bigger fish that eat smaller fish. Because of this chain, some fish have bigger concentration of mercury in their body.
In fact, all fish contain traces of mercury. For most people this is not a problem because those small amounts cannot hurt their health. However, greater amounts can pose a serious risk for unborn and newborn babies. That is why pregnant and nursing women must be careful not to eat too much fish that is believed to contain more mercury.
Young children, especially if under six years of age, should eat two servings of fish a week and parents should choose the kinds that do not have high mercury content.
Long-term high intake of mercury can build up in the body and cause kidney and brain damage.
Fish with lowest and highest amount of mercury
Generally, fish that live longer have higher concentration of mercury in their bodies.
Fish that have low mercury content can be consumed in two or three servings a week. This includes anchovies, clams, crabs, crawfish, haddock, herring, mackerel, mullet, oyster, perch, salmon, sardines, shrimps, squid, trout and whitefish.
Fish with moderate mercury should be eaten six times or less per month, while pregnant and nursing women and very young children should avoid them altogether. These fish are carp, cod, halibut, lobster, snapper and canned light tuna.
High mercury concentration can be found in bluefish, grouper, sea bass and albacore and yellowfin canned tuna. It is recommended to eat them three times or less per month, except for pregnant and nursing women and children who should not eat them at all.
Fish that is not supposed to be consumed because it has the highest mercury content is marlin, shark, swordfish tilefish and ahi tuna.