Fish may aid fetal brain development

New research suggests that fish may indeed be brain food, at least those varieties that have low levels of mercury.

In a study of 135 mothers and their infants, researchers at Harvard Medical School in Boston found that mothers' fish consumption during pregnancy seemed to aid fetal brain development. Overall, the greater a woman's fish intake during the second trimester, the better her 6-month-old performed on a standard test of mental development.

On the other hand, when mothers had fairly high mercury levels - as measured in hair samples - their babies tended to have relatively poorer test scores.

The implication, according to the researchers, is that fish can be a brain-healthy food for women to have during pregnancy - but only if they eat varieties likely to have little mercury contamination.

Mercury is a metal that occurs in the environment both naturally and as a product of industrial pollution. Most fish and shellfish have some level of mercury, but certain large, long-lived fish are likely to accumulate high levels of the pollutant, which can damage the developing fetal brain.

Eating moderate amounts of fish - and its added ingredient, mercury - appears to pose little danger to the brains of older adults, according to new study findings released Tuesday.

Among a group of older adults between 50 and 70, those with more mercury in their blood appeared to perform equally well in multiple tests of mental functioning as people with lower blood mercury levels.

In fact, according to the Journal of the American Medical Association report, older adults with higher mercury levels tended to outperform others on tests of manual dexterity involving finger tapping.
More information: Mercury in fish seems not to harm older brains

Because of this, health officials in the U.S. advise pregnant women to avoid certain fish-namely, shark, swordfish, king mackerel and tilefish.

Yet fish also provide a number of important nutrients, including omega-3 fatty acids, which may support fetal brain development.

The new findings, published in the journal Environmental Health Perspectives, point up this potential benefit.

"Women should continue to eat fish during pregnancy but choose varieties with lower mercury contamination," conclude Dr. Emily Oken and her colleagues.

Safer fish choices include canned light tuna, which has less mercury than albacore tuna, and other small fatty fish like salmon, Oken told Reuters Health. White-meat fish like cod and haddock tend to have low mercury levels-though, she noted, they also have lesser amounts of the beneficial omega-3 fats.