Check with your doctor first

A recent NIH study determined that an infant is apt to be smarter if the mother eats fish during pregnancy. The study by Emily Oken, M.D., Harvard Medical School finds that 6-month-old babies whose mothers ate two or more servings of fish a week in the second trimester scored highest on visual memory tests, a sign of IQ. But heed this warning: Mothers must eat only fish low in mercury. Babies of fish-eaters with high levels of mercury scored much lower on tests.

Safe choices: Oken advises pregnant women to continue eating fish but to choose fish low in mercury: salmon, canned light tuna, sardines, white fish. Shellfish are OK but low in omega-3 fat. Avoid shark, swordfish, fresh tuna and canned albacore tuna because all are higher in mercury.

ARE capsules OK? Oken says she isn't sure fish oil capsules would work as well as eating fish. But they are safer, says Kent Lewandrowski, M.D., of Massachusetts General Hospital and a pathology professor at Harvard Medical School. In tests, he and his associates found only negligible amounts of mercury and other toxins in commercial fish oil capsules. And he prefers to take fish oil capsules to lower his risk of cardiovascular disease; mercury in fish can negate the benefits of omega-3 fat. He also advises his own teenagers to take fish oil. But he says everyone, especially pregnant women, should check with a doctor before taking fish oil.

Scientific sources
Maternal fish consumption and infant cognition
Oken, E, Environmental Health Perspectives, 2005 Oct; 113(10):1376-80; http://ehp.niehs.nih.gov/members/2005/8041/8041.pdf

Mercury levels in fish oil capsules
Melanson, SF, Arch Pathol Lab Med 2005; 129:74-77
Foran SF, Arch Pathol Lab Med 2003 Dec; 127(12): 1603-5

Fish oil capsule use
Interview with Kent Lewandrowski, M.D., of Massachusetts General Hospital and Harvard Medical School