Oct. 4, 2007 -- A group of experts in maternal nutrition and obstetrics announced today a new recommendation that pregnant women should eat at least 12 ounces of seafood per week, a sharp turn from previous Food and Drug Administration recommendations.
The recommendations come as the latest volley in a long-running debate over the safety of seafood for pregnant women. Most of the concerns have centered on whether methyl mercury, a trace element that can accumulate in certain fish, can accumulate to levels that are dangerous to developing fetuses.
The Maternal Nutrition Group, comprising 14 nutritionists, physicians and dietitians from academic centers around the country, made the announcement today together with the nonprofit group National Healthy Mothers, Healthy Babies Coalition.
In the statement, the group recommended that pregnant, breast-feeding and postpartum women consume a minimum of 12 ounces of seafood a week as part of an overall healthy diet -- as long as only 6 of the ounces of seafood per week come from albacore tuna because of its mercury content.
The recommendations stated that ocean fish, including salmon, tuna, sardines, and mackerel, were an important source of omega-3 essential fatty acids, such as docosahexaenoic acid (DHA) and eicosapentaenoic acid.
In its statement, the group stated that such fatty acids were essential during rapid fetal growth and development. DHA, in particular, is known to accumulate in fetal brains largely during the late prenatal and early postnatal periods.
"We've looked at the science of how the brain develops and how to improve pregnancy outcomes," said group member Dr. Patricia Nolan, associate professor in the Department of Community Health at Brown University. "We have found there is a lot of evidence that DHA is very important in our developing nervous system."
The group also stated that its review of scientific literature suggested that improved consumption of such fatty acids may lead to improved visual, cognitive, motor and behavioral skills that last into childhood.
Have Your Fish ... and Eat it Too
In 2001, the FDA co-issued an advisory with the Environmental Protection Agency recommending against the consumption by pregnant women of certain types of fish -- particularly shark, swordfish, king mackerel and tilefish.
It recognized that seafood could still be an important part of an overall diet but recommended no more than 12 ounces per week. The FDA revisited the issue in 2004, and stood by its recommendations.
Group member Dr. Paul Ogburn, director of maternal and fetal medicine at the Stony Brook University School of Medicine, disagreed.
"While there are some fish that have more DHA and eicosapentaenoic acid and some that have more mercury, there is virtually no fish that has toxic levels of mercury and no fish that doesn't have reasonable levels of essential fatty acids," he said. "While one can go around looking at all the different numbers, we can say 12 ounces of seafood per week is safe and healthy."
Some experts, however, point out that the focus of the debate may be on the wrong question. Rather than examining whether seafood as a whole is safe or unsafe for pregnant mothers and their developing fetuses, the question should really be on which types of seafood provide beneficial effects such as omega-3 fatty acids without being reservoirs of the potentially dangerous methyl mercury.
"Apart from the politics, this is a nonissue," said Ellen Silbergeld, professor in Environmental Health Sciences at the Johns Hopkins School of Public Health. "It is widely known that one can have one's cake and eat it too. All it takes is to choose wisely among the fish that one consumes."
Biologically, the concept is called bioaccumulation: Mercury found either naturally or as pollution in the world's waters gets taken up initially by microorganisms. As these are eaten by small animals and subsequently by larger and larger fish, the concentration of methyl mercury increases with each successive step in the food chain.
The result is that so-called "top predators" usually have higher levels of potentially toxic chemicals.
"Due to bioaccumulation," said Silbergeld, "a top predator such as a tuna or a swordfish can have levels of mercury up to 60,000 to 80,000 times that of water."
With regards to being able to measure mercury levels in different types of fish, Silbergeld said, "The bottom line is that it is easy. There are a number of organizations that have done this. We know where the high end lies and where the low end lies."
Schooling Yourself on Fish
Meanwhile, clinicians and patients are beginning to understand that one way to clear up the confusion may lie in educating themselves.
"People are not always cognizant of which fish are beneficial and which are not," said Dr. Ashlesha Dayal, assistant professor in maternal and fetal medicine at the Albert Einstein College of Medicine.
"The problem is that when something gets bad press, it will stick in patients' minds, and the immediate instinct is to back away," she said. "Until they hear that it is safe and OK, it will take a bit of education."
Multiple Web sites now have easy-to-carry cards that list "good fish" and "bad fish" with regards to omega-3 fatty acid benefits and mercury risks. For a list of such Web sites, see the links below:
Purdue University http://fn.cfs.purdue.edu/fish4health/Walletcard/walletcard.htm
National Resources Defense Council http://www.nrdc.org/health/effects/mercury/walletcard.pdf