Pregnant women need fish for fetus

Women wanting to boost their babies’ cognitive development need to tread a fine line in fish consumption to avoid excess mercury, suggests a new study on the risks posed by mercury and the benefits of omega-3.

A raft of studies has indicated that omega-3 has an important role to play in brain development, as well as the prevention of heart disease and certain cancers and promotion of bone health. But just as consumers are becoming more aware of omega-3 and its benefits, a note of caution has issued from the FDA on organic mercury levels in fish, one of the best natural sources of the fatty acid.

Certain fish contain higher levels of mercury, which is believed to affect the development of a baby or young child’s nervous system. The FDA therefore recommends that pregnant women and nursing mothers eat up to 12 ounces (two average meals) of fish that are low in mercury each week in order to support fetal brain development. Varieties such as shrimp, canned light tuna, salmon, Pollock and catfish are lowest in mercury.

Since albacore or white tuna contains more mercury than light tuna, it should be restricted to one 6 ounce serving per week. Shark, swordfish, king mackerel and tilefish, which contain high levels of mercury, should be avoided altogether. Researchers set out to study whether women’s fish consumption, when pregnant, harms or benefits fetal brain development.

The study group consisted of 135 mother and infant pairs who were involved in Project Viva, a prospective pregnancy and child cohort study. The mothers recorded their consumption of canned tuna, shellfish, dark meat fish and other types of fish in a food frequency questionnaire throughout the second trimester. On average, they ate 1.2 servings of fish.

At six months, the infants’ cognitive ability was assessed using visual recognition memory (VRM) testing. The research team found that higher fish intake was associated with higher infant cognition. However, in increase of 1ppm of maternal mercury resulted in a 7.5 drop in VRM score. It was determined that infants whose mothers consumed more than two servings of fish per week, but had mercury levels of 1.2ppm or lower had the highest VRM scores. “Women should continue to eat fish during pregnancy but choose varieties with lower mercury contamination,” wrote the researchers in the October issue of Environmental Health Perspectives.

In a white paper issued in July, the Council for Responsible Nutrition advised the general population to increase its intake of oily fish or take supplements to obtain protective intake levels of about 0.5g of omega-3 per day. Although dietary supplements were outside the scope of the Harvard study, they may prove beneficial for people who are concerned about the detrimental effects of mercury levels or who have some other aversion to fish.

It is incredibly important to not just consume any old fish oil supplement. Most of the brands you find at the drug store or at Costco have not been screened for heavy metals. Make sure you check brands with a health care provider that is up on this research before consuming fish oil supplements. If you can manage taking fish oil by the teaspoon, Carlson’s cod liver oil has no heavy metals. If you prefer the encapsulated version, Rx Fish Oil is a safe brand. Carlson’s can be found at certain health food stores and the capsule version at the Family Health Clinic.