Canned Tuna: Avoid if Pregnant?

June 5, 2006 -- Recommendations published in the magazine Consumer Reports this week urge women to avoid eating any canned tuna while pregnant because of uncertainties about the risk of mercury contamination to developing fetuses.

The recommendations are stricter than the federal government’s advice issued two years ago. Then, the FDA advised women and young children to limit -- but not avoid -- consumption of canned tuna because of contamination.

But the magazine’s experts say women should avoid the popular item altogether because of FDA data showing that some canned tuna may have higher mercury levels than once thought.

“What we did is take a closer look at the data,” says Urvashi Rangan, PhD, a toxicologist and a senior scientist at Consumer Reports.

Higher-Than-Average Levels

Canned tuna and most other fish and seafood contain some amount of toxic mercury that has worked its way through the food chain because of industrial pollution. In adequate doses the metal can damage the developing nervous system in fetuses and children.

The FDA specifically warns against the consumption of shark, swordfish, king mackerel, or tile fish -- which have high levels of mercury -- by women who are nursing, or women who are pregnant or of childbearing age; the FDA warning also applies to young children.

In 2004, the FDA urged women and young children to eat no more than 12 ounces of a variety of fish and shellfish with lower levels of mercury (including canned light tuna) or 6 ounces of white tuna (albacore) per week to minimize mercury risks. Canned light tuna on average contains lower mercury levels, the agency said.

But the Consumer Reports analysis of the FDA’s data shows that 6% of cans of light tuna contained at least as much mercury as white tuna, also known as albacore. It wasn’t enough to skew the average beyond white tuna, but enough to warrant concern for pregnant women, Rangan says.

“We’re not telling you not to eat tuna. But for pregnant women in particular where you are talking about potential fetal exposure -- and it’s an avoidable risk -- we’re saying go ahead and take some extra measures to reduce your Hg [mercury] exposure at all costs,” she tells WebMD.