You’ve likely heard that fish is great for you but, when it comes to tuna, it may be a different story. Mercury is the primary concern in big fish like tuna. Pollution releases mercury into the air, and as it accumulates in the ocean, fish absorb it from the waters and their mercury stores build up, according to the US Food and Drug Administration (FDA). A recent study from the University of South Florida found that patients with high levels of mercury in their bloodstream — amounts that often exceed what the Environmental Protection Agency (EPA) deems safe — may experience a 5 percent dip in cognitive function. But before you swear off all seafood, don't! Salmon, sardines, and mackerel are low in mercury and high in brain-boosting omega-3s.
