Canned tuna, Americans’ favorite fish, is the most common source of mercury in our diet. Consumer Reports’ new tests of 42 samples from cans and pouches of tuna bought primarily in the New York metropolitan area and online confirm that white (albacore) tuna usually contains far more mercury than light tuna.
Children and women of childbearing age can easily consume more mercury than the Environmental Protection Agency considers advisable simply by eating one serving of canned white tuna or two servings of light tuna per week. A serving is about 2.5 ounces. Expect a 5-ounce can to contain about 4 ounces of tuna plus liquid.
The heavy metal accumulates in tuna and other fish in an especially toxic form, methyl -mercury, which comes from mercury released by coal-fired power plants and other industrial or natural sources, such as volcanoes.
Fortunately, it’s easy to avoid tuna and to choose lower-mercury fish that are also rich in healthful omega-3 fatty acids. That’s especially important for women who are pregnant or might become pregnant, nursing mothers, and young children, because fetuses and youngsters seem to face the most risk from methyl mercury’s neurotoxic effects.
How much tuna is safe
Canned tuna, especially white, tends to be high in mercury, and younger women and children should limit how much they eat. As a precaution, pregnant women should avoid tuna entirely.
(This article is adapted from the January 2011 Consumer Reports magazine.)