Yet again fish is a good news, bad news food. According to multiple studies, regular fish consumption -- about 2 servings per week, or about 12 oz total -- is linked to greater longevity. But mercury contamination of fish, which occurs when industrial pollution containing the poisonous metal gets into lakes and streams where the fish absorb it, remains a serious health hazard and raises questions about the role of fish in an anti-aging diet.
A new study published in the Archives of Pediatrics and Adolescent Medicine highlights the ongoing controversy about fish, this time in relation to attention deficit hyperactivity disorder, or ADHD, and the impact a mother's diet had while pregnant. According to the press release and study abstract, the researchers tracked about 400 Massachusetts children, assessing their mothers for mercury exposure levels before giving birth -- and then testing the children 8 years later for behaviors typically associated with ADHD, such as inattentiveness and impulsiveness.
Their findings? There was a greater incidence of ADHD-related behavior among children whose mothers had higher mercury levels -- and a lower incidence of such behaviors among children whose mothers ate fish more than twice a week. Though the researchers did not determine that mercury causes ADHD in children, the results found behaviors often seen in ADHD were linked to higher exposure.
How can you benefit from the nutrition found in fish, while avoiding dangerous mercury exposure yourself? Fortunately, you can navigate these confusing waters, just by limiting certain types of fish known to contain the most toxic mercury. These are large, predatory species like shark, swordfish, and tilefish that accumulate mercury in their muscle tissue from water they swim in, and from smaller fish that they eat.
Several fish species contain low levels of mercury, including salmon, shrimp, sole, and canned light tuna. The many benefits of fish for heart health, brain development in infants and children, and nutrition in general can be enjoyed while still avoiding dangerous mercury exposure.
Sharon K. Sagiv, PhD, Sally W. Thurston, David C. Bellinger, Chitra Amarasiriwardena, Susan A. Korrick. "Prenatal Exposure to Mercury and Fish Consumption During Pregnancy and Attention-Deficit/Hyperactivity Disorder-Related Behavior in Children."
Arch Pediatr Adolesc Med. 2012;():1-9.