Eating certain types of fish with even low levels of mercury while pregnant can increase the risk for attention-deficit/hyperactivity disorder (ADHD) in offspring, whereas consumption of several other types of fish during pregnancy may protect against the disorder, new research suggests.
A cohort study of almost 400 children showed that the risk for inattention and impulsivity at the age of 8 years was significantly associated with maternal mercury levels of at least 1 μg/g. In addition, as the mercury levels increased, so did risk.
However, when the mothers ate at least 2 servings of fish a week, the risk for ADHD symptoms decreased.
"However, offspring of mothers who consumed at least 2 servings of fish a week, which is currently more than the current recommended amounts from the US Food and Drug Administration and the Environmental Protection Agency, had a decrease in ADHD-related behaviors — especially in impulsivity/hyperactivity (relative risk [RR], 0.4 vs 2 servings or fewer of fish per week)."
"These findings underscore the difficulties of balancing the benefits of fish intake with the detriments of low-level mercury exposure in developing dietary recommendations in pregnancy," write the investigators.
"Although the researchers did not assess which fish are worst and best to consume while pregnant, they noted in a release that previous studies have shown that shark, fresh tuna, and swordfish should be avoided by pregnant women, whereas fish such as haddock, salmon, and flounder are good because of their low levels of mercury and their nutritional value."
Sagiv SK, Thurston SW, Bellinger DC, Amarasiriwardena C, Korrick SA. Prenatal Exposure to Mercury and Fish Consumption During Pregnancy and Attention- Deficit/ Hyperactivity Disorder-Related Behavior in Children.
Arch Pediatr Adolesc Med. 2012 Oct 8:1-9. doi: 10.1001/archpediatrics.2012.1286.