Researchers at Harvard University analyzed the benefits and risks of eating fish, a potential source of mercury and dioxin contamination. They calculated that eating one to two fish meals per week, especially fish high in omega-3 fats, reduced the risk of death from heart disease by 36 percent and death from other causes by 17 percent. The researchers wrote that women of childbearing age and nursing mothers should consume two seafood meals per week, but limit their consumption of high-mercury fish, such as shark, king mackerel, swordfish, and golden bass.

Docosahexaenoic acid (DHA), one of the omega-3s, is important in the development of fetal and infant brains. The researchers noted that consuming 250 mg daily of DHA and eicosapentaenoic acid (EPA) may be sufficient for heart protection. They concluded that, "for major health outcomes among adults...the benefits of fish intake exceed the potential risks. For women of childbearing age, benefits of modest fish intake, except for a few selected species, also outweigh risks."