The Right Fish for Moms Helps Babies’ Brains

May 8, 2008—Omega-3 fatty acids from fish offer many benefits to developing babies during pregnancy. But do contaminants such as mercury make eating fish unsafe? According to a new study in the American Journal of Epidemiology, pregnant women who eat two or more servings of fish each week may be providing their children with important nutrients that aid in cognitive development. Choosing fish with low mercury content appears to be even more beneficial.

Fish contains important nutrients such as omega-3 fatty acids and is generally high in protein and low in saturated fat. Many studies have suggested that eating fish several times per week is good for heart health and for preventing diseases such as a cancer. But fish may also contain contaminants such as unhealthy mercury. As a result, the Environmental Protection Agency (EPA) recommends that pregnant women not eat more than two 6-ounce servings of fish per week.

The authors of this new study were concerned that if pregnant women limit fish intake, their babies may not receive enough omega-3 fatty acids, which could impair the brain’s cognitive development. To determine the risks and benefits of eating fish during pregnancy on child development, the authors looked at dietary habits of 341 pregnant women, their mercury levels during pregnancy, and the cognitive development of their children at age three.

Women who ate the most fish (more than two servings per week) had higher mercury levels. However, higher fish intake was associated with better cognitive test performance, regardless of mercury levels. Compared with the children of women who never ate fish, the children of women who ate more than two servings of fish per week but had the lowest mercury levels had better cognitive test performance.

“Recommendations for fish consumption during pregnancy should take into account the nutritional benefits of fish as well as the potential harms from mercury exposure,” said Emily Oken, MD, and her colleagues from Harvard Medical School and Harvard School of Public Health. The authors believe that if mercury contamination were not present, the cognitive benefits of eating fish would be greater. They point out that other contaminants such as polychlorinated biphenyls may also be present in fish and were not measured in this study but may have an adverse effect on child development.

Best bets for eating fish during pregnancy

For women who are or may become pregnant, choose fish that are likely to have lower mercury levels such as:

• Canned light tuna

• Shrimp

• Salmon

• Pollock

• Catfish

The EPA points out that fish that is used for fish sticks or fast food sandwiches tend to be fish that are lower in mercury content. Fish best avoided by pregnant women include shark, swordfish, king mackerel, and tilefish.

(Am J Epidemiol 2008 Mar 28)

(What You Need to Know About Mercury in Fish and Shellfish. Environmental Protection Agency. www.epa.gov/waterscience/fish/advice/)

Jane Hart, MD, board-certified in internal medicine, serves in a variety of professional roles including consultant, journalist, and educator. Dr. Hart, a Clinical Instructor at Case Medical School in Cleveland, Ohio, writes extensively about health and wellness and a variety of other topics for nationally recognized organizations, Web sites, and print publications. Sought out for her expertise in the areas of integrative and preventive medicine, she is frequently quoted by national and local media. Dr. Hart is a professional lecturer for healthcare professionals, consumers, and youth and is a regular corporate speaker.

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