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Posted on Nov 14, 2006, 7 a.m.
By Bill Freeman
Despite the threat of mercury and other contaminants, the health benefits of eating fish exceed the potential risks, according to a report published today in the Journal of the American Medical Association. 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 -- both finfish and shellfish -- 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.
Fish -- both finfish and shellfish -- 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.
"The public is faced with seemingly conflicting reports on the risks and benefits of fish intake, resulting in controversy and confusion over the role of fish consumption in a healthy diet," note Dr. Dariush Mozaffarian and co-author Eric B. Rimm of the Harvard Medical School, Boston, in their report.
The two investigators 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 -- EPA and 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 favorably 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 minimize 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, Mozaffarian and Rimm add. This includes fish caught locally with safety advisories.
"However, emphasis must also be placed on adequate consumption -- 12 ounces per week -- of other fish and shellfish to provide reasonable amounts of DHA and avoid further decreases in already low seafood intake among women," they state. It's estimated that 74 percent of women of childbearing age and 85 percent of pregnant women consume less than 6 ounces per week.
According to the authors, 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.
The authors also recommend consuming a variety of seafood and those who eat a lot of fish (5 servings or more per week) should limit intake of species highest in mercury levels.
Levels of dioxins and PCBs in fish are "low," they also report.
In summary, Mozaffarian and Rimm write: "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."
"For women of childbearing age, benefits of modest fish intake, excepting a few selected species, also outweigh risks."
