According to Consumer Reports, America’s favorite fish – canned tuna – is the most common source of mercury in our diets. In their recent study, all 42 samples of cans or pouches of tuna purchased in the New York metropolitan area and online contained measurable levels of mercury. Specifically, white (albacore) tuna usually contains far more mercury than light tuna.
Tuna accumulates mercury in their flesh as a result of industrial pollution from coal-fired power plants and natural sources, such as volcanoes.
For most people, the health concerns associated with consuming fish and shellfish with traces of mercury are a non-issue. However, this is an issue for unborn babies or young children, so the FDA and EPA recommend that pregnant women and young children avoid eating shark, swordfish, king mackerel, and tilefish.
Incidentally, the FDA also provided a list of the five fish recommended for eating due to their low mercury content, and that list included canned light tuna (along with shrimp, salmon, pollock, and catfish).
While there seems to be confusion about exactly which fish are safe to eat and which aren’t, the FDA seems confident in prescribing an amount to consume; eating 12 ounces (2 average meals) a week of a variety of fish and shellfish that are lower in mercury will still provide the benefits of fish’s omega-3 fatty acids.