Harvard Men's Health Watch

Is mercury in fish dangerous?

Q. I keep reading about health benefits of eating fish, but I've also heard that fish contain high levels of mercury. Should I be concerned?

A. Most men do not need to worry about mercury exposure from eating fish. Currently, there is no medically based suggested limit on the amount of fish men should eat, but you could take mercury content into account when considering what types of fish to eat. On the other hand, pregnant woman and young children are advised to avoid eating certain fish and to limit overall fish consumption to two servings per week.

Mercury is present in numerous environmental sources. It enters the food supply as organic mercury (methylmercury). Fish, especially the larger predator fish, concentrate the mercury in their bodies as they consume smaller creatures. The highest levels are seen in swordfish, king mackerel, shark, and albacore (white) tuna. Mercury exposure has been linked to neurologic problems in the developing fetus, but the effects on health in adults are less certain. Studies on the effects of mercury on blood pressure and heart disease have been inconsistent.

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