Canned tuna made news last week as the star in a scandalous debate: A coalition of consumer groups is reportedly urging schools to take tuna off the lunch menu. The reason? A recently published study that reported higher amounts of mercury than expected, as well as large variances in the levels of mercury, based on tests of several different brands and types of canned tuna.
For close to a decade, consumers have been warned about certain types of fish that may contain high amounts of mercury—the U.S. Food and Drug Administration even has an official guidance policy on the topic. The FDA recommends that people who are most vulnerable (pregnant women, infants, and children) be cautious about the type and amount of seafood they eat. In general, canned tuna has been considered safe to eat once or twice weekly; canned light tuna has been considered a bit safer than canned albacore tuna, but both are allowed in the diet of a child, according to the federal guidelines.
The alternative guidelines published and promoted by the consumer group coalition offer much more detailed guidance to parents and schools on what the authors call "risk-management advice." The most alarming of the recent study's findings were that some children, called "tuna lovers" by the authors, may be getting dangerously high doses of mercury, because they are simply eating too much canned tuna. For these children, the report recommends that parents request a blood test for mercury levels and try to cut down overall tuna intake.
Here are some of the key guidelines released in this report:
• Children should never be fed canned albacore tuna. The report found higher levels of mercury in albacore tuna than previously thought, and the authors concluded that there is no reason to include this type of tuna in a child's diet, when they could have canned light tuna, instead.
• Children who are small (under 55 pounds) should eat canned light tuna no more than once a month. Children over 55 pounds can have canned light tuna twice a month. Federal guidelines allow canned light tuna twice a week for all children.
• Schools, parents, and caregivers should coordinate when children are fed canned tuna, so they don't receive more than two such meals a month.
• Schools and parents should consider serving other types of seafood, such as salmon or shrimp, that aren't typically high in mercury.
So why not simply cut canned tuna out of a child's diet altogether? Because there are nutritional benefits to eating this type of seafood: Tuna is a lean protein source, contains omega-3 fatty acids critical for the brain and nervous system, and is fairly inexpensive for schools and families. Seafood is also an excellent source of the mineral selenium, which some evidence suggests helps "bind" mercury in the body, making toxicity less likely.
The bottom line is that we probably do need to be careful with over-exposing young children to mercury, but we don't need to throw the baby out with the bath water. The wisest move? It's likely choosing canned light tuna over albacore, and mixing it up with other low-mercury seafood, like salmon and shrimp.
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Melinda Johnson, MS, RD, is the Director of the Didactic Program in Dietetics and lecturer for the Nutrition Program at Arizona State University, and a Spokesperson for the Academy of Nutrition and Dietetics. Follow her on Twitter @MelindaRD.