Current recommendations from the U.S. Food and Drug Administration suggest that pregnant women eat two to three weekly servings of fish and that they choose fish – such as salmon – that are lower in mercury content. Findings in a new study now suggest that high levels of a compound called DHA may outweigh some of the negative effects of higher-mercury fish such as tuna. This DHA is an omega-3 fatty acid that can play a critical role in brain growth and development.
For this study Spanish researchers followed about 2000 mothers and their children beginning in the women’s first trimester and continuing after their babies were born until the children turned 5. Children whose mothers ate three to four fish servings weekly had IQ scores 2.8% higher than the children whose moms ate less fish. Researchers also noted that the children of women who ate an average of 21 ounces of fish every week – that’s three to four servings – showed no signs that the mercury in that fish negatively affected their development.
Lead study author Jordi Julvez is a researcher at Barcelona’s Center for Research in Environmental Epidemiology. Julvez was surprised to learn that certain types of fish such as tuna or tilefish were linked to the biggest benefits. Pregnant women have been discouraged from consuming these fish because they contain higher levels of mercury. After the study, speculation is that the higher levels of omega-3 fatty acids in these fish “may either be masking the negative mercury effects, or may be overall more beneficial than the toxic effect of the mercury itself,” according to Julvez.
The concern about eating certain fish during pregnancy arose because previous findings suggested prenatal exposure to mercury in fish might increase the risk of developmental problems. A Harvard study published in the Journal of Pediatrics in 2004 tracked more than 800 children in Denmark’s Faroe Islands, where seafood is a dietary staple. That study found that by age 7, the children ‘s development tracked with their level of mercury exposure, and those exposed to double the limit set by the U.S. Environmental Agency were developmentally behind by 1.5 to 2 months, issues that did not improve as they aged.
This newest study was published online in the American Journal of Epidemiology. Because of the new research, the FDA and the EPA have emphasized the benefits of fish consumption for pregnant women, but remain cautious and advise a minimum intake and awareness by pregnant women, urging them not to consume larger fish known to have a greater mercury content.