Expert Q&A

Fish: Does mercury cancel its health benefits?

I’ve heard that eating fish is better than eating red meat. But what about all the mercury? Does mercury make fish less healthy than other meats?

-Barbara from Idaho

Sometimes all the noise from the warnings prevents us from hearing the good news. It’s true that environmental pollution, particularly mercury from burning coal or other industrial waste, can accumulate in fish. The longer a fish lives, the more mercury it will accumulate. That’s why larger fish can be a particular problem.

The risk of mercury in eating fish

Most of us do not consume enough fish to cause any harm. However, because of its toxicity for the immature nervous system mercury is potentially a significant problem for children and developing fetuses. Pregnant women, women who might become pregnant in the next year, and young children should completely avoid eating king mackerel, shark, swordfish, tilefish, wild striped bass, eel and bluefish. The rest of us should eat them rarely.

The benefits of omega-3 in fish

Fish contain significant amounts of beneficial omega-3 fatty acids which lower cholesterol and reduce the risk of heart disease. The benefits of one to two meals per week consisting of a 6-ounce piece of fish for men and non-pregnant women far outweigh any risks. Commonly eaten fish such as wild salmon, canned tuna, mackerel, mahi-mahi, oysters, clams, crab, farmed bass, scallops, sardines, and tilapia are safer. Prepared fish sticks and fish sandwiches have little or no mercury. Farm raised salmon, Chilean sea bass, orange roughy, bluefin tuna and grouper have more mercury and should be eaten less often but need not be avoided as these also have significant benefits. Pregnant women and children should have no more than half the amount of adult men.

Fish is an essential element of a healthy diet

Fish is an important part of a balanced diet. Don’t let undue worry about mercury stop you from including fish in your diet. The EPA provides a reference for how often to eat certain noncommercial species. You can also find another resource for the best and worst fish choices is here.

For further information on which fish are safe to buy see the following article from TheDietChannel: Fish Safety & Buying Guide.

For further information on eating fish when you are pregnant see the following article from TheDietChannel: Pregnancy Diet.

For further information on mercury intake when trying to conceive see the following article from TheDietChannel: Mercury: What's a safe intake for couples trying to conceive?

John Messmer, MD
Contributing Expert

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