The reports agreed that increasing media attention to seafood contaminants had obscured public health messages concerning seafood's benefits. Chemicals, metals, and harmful microbes can be found in seafood -- usually in different levels dependent on geographical region and species -- and the government issued a warning to pregnant women to reduce their consumption of certain species to reduce their risk of mercury exposure, but lead researcher of the Harvard study, Dr. Dariush Mozaffarian, said the American public latched onto this warning.
"Somehow the message has gotten lost in the public," Mozaffarian said. He added that he was surprised at how little evidence there was suggesting harm from the mercury in fish. Although research involving mercury spills has shown that large quantities of the chemical are extremely harmful to the brain, the effects of mercury at the low levels found in fish are not known.
"Both studies came to the same conclusion: Seafood is safe and nutritious, and Americans should incorporate a variety of seafood in their diet," said William T. Hogarth, director of the National Oceanic and Atmospheric Administration, of which the IOM is a division.
Both studies also noted the conflicting public health information released about the risks of consuming fish, and that the Harvard and IOM studies were based on scientific evidence rather than "fear and speculation," Hogarth said.
The Institute of Medicine was requested to make its recommendations on consumer choices about seafood consumption. The recommendations include: Women who are pregnant, breastfeeding, or who could become pregnant can safely consume two 3-ounce servings of cooked fish per week, but should avoid predatory fish like shark and swordfish as they tend to contain higher mercury levels; children under 12 can eat the same amount as pregnant women, and up to 6 ounces of white (albacore) tuna per week, but they should also avoid the same large predatory fish; women who will not become pregnant, and healthy adolescents and adult males can eat seafood regularly and may reduce their risk for cardiovascular disease, but a variety of fish should be selected if they eat more than two servings a week, so that risk of contaminant exposure is reduced; the risk of coronary heart disease can be reduced in adult men and women who eat seafood regularly, and they should increase the amount of omega-3 fatty acids in their diet, and also vary their seafood choices.
Several recommendations for the effective communication of health messages were also made by the IOM, such as federal agencies advising the public about the benefits of seafood and their potential to substitute beef and other protein sources higher in saturated fat. They also recommended both state and federal agencies establish an interagency task force in order to organize and synchronize information about seafood's benefits and risks.
The Harvard study, set for publication Wednesday in the Journal of the American Medical Association, agreed with the IOM study's assertion that the risk of environmental contaminants paled in comparison to seafood's health benefits. It also concluded that one or two servings of omega-3-rich fish a week can reduce the risk of fatality from a heart attack by 36 percent, and cut overall death rate by 17 percent, according to Mozaffarian and colleagues. Mozaffarian added that fish oil supplements would produce many of the same effects, but consumers would be depriving themselves of the protein and vitamins present in whole fish.