The selective focus of the media on the presence of mercury in canned and pouched tuna and other fish ignores the essential health benefits of eating this nutrient-rich food. It is important for consumers to know that there are unique benefits of enjoying fish like canned and pouched tuna, namely omega-3 fatty acids and other nutrients — which is why the American Heart Association recommends Americans eat two seafood meals per week.

When it comes to mercury, here is what you should know:

  • Very important benefits of consuming fish outweigh concerns about trace amounts of mercury. Numerous studies, including recent ones published in leading health journals such as The Lancet and The Journal of the American Medical Association, demonstrate that the benefits of seafood greatly outweigh any health concerns from mercury. In fact, the studies indicate that when pregnant women avoid fish in an attempt to lower their exposure to mercury, they risk missing out on health benefits that can include improved brain, eye and motor function in their children.
  • A study of more than 11,000 women, published in The The Lancet, shows that mothers who consumed more than 12 ounces of fish each week during their pregnancy, which has resulted in higher mercury levels, actually have the best health outcomes for their children. These benefits included stronger motor, communication and social skills than children of mothers who eat little or no seafood, and thus have lower levels of mercury.
  • Seafood should be viewed differently than other mercury sources because of the protective benefits of omega-3 fatty acids. In addition, early results from another study indicates that selenium, which is abundant in canned tuna, may actually offset even minimal risks of mercury. Selenium is essential for human development, including thyroid function, and also reduces the risk of some cancers.
  • Trace amounts of mercury have been present in fish since the beginning of time. Mercury is a naturally occurring substance that mostly comes from volcanic activity and ocean thermal vents. Some mercury has been added by man, but data shows that over time the amount of mercury in the ocean remains essentially the same. A study led by Princeton University researcher Francois Morel compared mercury levels in Yellowfin tuna caught off the coast of Hawaii in 1998 with mercury levels of fish caught in the same area in 1971. The study found no increase in mercury levels.
  • Taking fish oil supplements to try to avoid mercury may not be as beneficial as eating canned or pouched tuna as a meal. A recent study in Current Opinion in Clinical Nutrition and Metabolic Care shows that consuming fish, rather than omega-3 supplements like flax seed or fish oil, is the best approach for the health of women and their children.
  • Mercury found in hair tests does not prove harm to human beings. Such tests prove only an exposure to mercury. Studies from the National Academy of Science, Harvard School of Public Health and National Institutes of Health all point to the importance of continuing to eat fish, including canned tuna, and placing the exposure to mercury in the context of seafood's benefits.
  • Tuna is one of the most commonly consumed fish, popular for its taste, convenience and affordability. It represents one of the best ways for Americans to get omega-3s in their diet. Consumers who shy away from fish, including canned tuna, may experience a nutritional deficiency that is even more pronounced in pregnancy.

References:

Morel FM, Malcolm EG, Chin HB, Keller K, Kraepiel AM. Sources and Variations of Mercury. Environ. Sci. Technol. 2003; 37: 5551-5558.

Hibbeln JR, Davis JM, Steer C, Emmett P, Rogers I, Williams C, Golding J. Maternal seafood consumption in pregnancy and neurodevelopmental outcomes in childhood (ALSPAC study): an observational cohort study. Lancet 2007; 369:578-85.

Mozaffarian D, Rimm EB. Fish Intake, Contaminants, and Human Health: Evaluating the Risks and the Benefits. JAMA 2006; 296: 1885-1900

Racine RA, Deckelbaum RJ. Sources fo the very-long-chain unsaturated omega-3 fatty acids: eicosapentaenoic acid and docosahexaenoic acid [Lipid metabolism and therapy]. Current Opinion in Clinical Nutrition and Metabolic Care 2007; 10: 123