Despite the threat of mercury and other contaminants, the health benefits of eating fish exceed the potential risks. This holds even for women who are or who may become pregnant and nursing mothers, with the exception of some specific species of fish. Fish has long been considered a healthy food due to high levels of heart-protecting omega 3-fatty acids. Yet, concern abounds over potential harm from mercury, dioxins, and PCBs present in some species of fish. Researchers from the Harvard Medical School, Boston, took a critical look at the scientific literature for harmful and beneficial health effects of eating fish. They found that one to two servings of fish per week, especially fish high in the two omega-3 fatty acids: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) reduces the risk of heart-related death by 36 percent and death from any cause by 17 percent. Two meals of fish weekly may also favourably affect other clinical outcomes. Specifically, the data show that consumption of 250 milligrams per deciliter of EPA and DHA appears to offer sufficient protection. This is equivalent to one 6-ounce serving per week of wild salmon or similar oily fish, or more frequent intake of smaller or less omega-3 fatty acid-rich servings. Available data also suggest that DHA specifically benefits the developing nervous system of infants, yet at the same time low levels of mercury in fish may adversely affect early neurodevelopment. To minimise mercury exposure, women who are or may become pregnant and nursing mothers should avoid shark, swordfish, golden bass, and king mackerel, which have high mercury levels. According to the researchers, the health effect of low-level mercury intake in adults is not clearly established in the scientific literature; mercury may modestly decrease cardiovascular benefits of fish intake. For major health outcomes among adults, based on both the strength of the evidence and the potential magnitudes of effect, the benefits of fish intake exceed the potential risks.
Journal of the American Medical Association,
October 2006