In the US and UK, official dietary advice in recent years has mainly emphasised the possible risks from mercury, and cautioned pregant mothers to limit their intake of fish and seafood.
After studying the evidence, a coalition of leading scientists now says that any such risks are far outweighed by the nutritional benefits of fish and seafood.
In particular, these foods are the main sources of omega 3-fats essential for healthy brain development and function (EPA and DHA), for which average dietary intakes are already suboptimal. Fish and seafood also provide high quality protein and important trace elements including selenium (which helps to inactivate mercury), and are one of the few dietary sources of Vitamin D (otherwise derived from sunlight), which many women in developed countries are lacking.
Suspicions that the current official advice may be doing more harm than good were fuelled by results from a recent Lancet study,(Hibbeln et al, 2007) showing that higher intakes of fish and seafood by mothers during pregnancy were associated with better developmental outcomes in children.
A re-evaluation of official dietary advice is called for, and this time including the potential benefits, not just the risks.
For more information on the recommendations of the US coalition of scientists, see
Advisory at Odds With FDA Stance
Pregnant and breast-feeding women should eat at least 12 ounces of fish and seafood per week to ensure their babies' optimal brain development, a coalition of top scientists from private groups and federal agencies plans to declare today in a public advisory that marks a major break with current U.S. health advice.
The scientists' conclusion is at odds with the standard government advice issued in 2001 that new mothers and mothers-to-be should eat no more than 12 ounces of seafood per week because of concerns about mercury contamination.
Shifting data and advice on how women's consumption of fish and seafood affects brain development of fetuses and infants, the most vulnerable groups, have produced one of the more vexing nutritional dilemmas of recent years.
In the short term, at least, today's statement, drafted by scientists affiliated with multiple medical organizations, is likely to deepen the dilemma for many women, especially since the Food and Drug Administration indicated that it will study the new information but is not prepared to change the advice it reiterated in 2004.
"There is a big debate about what is safe," said Brown University professor Patricia Nolan, a former state health officer of Rhode Island and one of the experts who drafted the new guidelines. "There are really complex questions. That is why we are doing this."
At the core of the problem is the tension between the brain-bolstering nutrients in seafood and concern over exposure to mercury, which builds up in the tissue of many marine species and is toxic to nerve tissue.
Practicing physicians such as New York University obstetrician Ashley Roman, herself a new mother, expect the questions about seafood and mercury to intensify.
"Every single day, I get questions from my patients about this, because it is such a confusing area," said Roman, who served on the panel that offered the new advice. "Personally, for me in my practice, it doesn't change what I have already been recommending, which is to have at least three servings of fish a week."
The first thing Roman said she tells her patients is that "fish intake in pregnancy has never been linked with mercury toxicity" in fetuses or newborns, while highlighting the benefits to mother and baby.
Fish and seafood are the major dietary sources of omega-3 fatty acids, especially a substance called docosahexaenoic acid (DHA). They are key nutrients for the brain and nervous system in developing fetuses, infants and young children.
The advisory set to be released today at a Washington news conference comes from the National Healthy Mothers, Healthy Babies Coalition. The coalition is a nonprofit group with nearly 150 members, including the American Academy of Pediatrics and the March of Dimes, as well as federal agencies including the National Institute of Child Health and Human Development and the Centers for Disease Control and Prevention.
Concerns about mercury contamination prompted the FDA and the Environmental Protection Agency to issue consumer advisories in 2001 and again in 2004. Pregnant and breast-feeding women, those who wanted to become pregnant, and young children were told to eat no more than 12 ounces weekly of fish or seafood, a number based on theoretical calculations of the potential for contamination.
The FDA and EPA also recommended that these groups avoid eating shark, tilefish, king mackerel and swordfish because of high mercury content, and to eat no more than six ounces per week of albacore tuna. The agencies say that for most other people, the mercury in fish and shellfish poses no risk.
Consumers seemed to take that advice to heart and were reinforced by the popular self-help book "What to Expect When You're Expecting." It said that when it comes to fish, pregnant women, as well as nursing mothers and young children, "should play it safer than the general population."
The federal seafood warning led 56 percent of pregnant women to cut fish consumption to levels well below beneficial amounts, according to a study conducted earlier this year at the Medical University of South Carolina.
When women skimp on fish, dubbed "brain food" by previous generations, their babies and children can sometimes pay the price, other studies indicate. Earlier this year, a team of British and American scientists reported in the Lancet that children of women who ate the smaller amounts recommended in the United States during pregnancy had lower IQs and lower academic test scores at age 8, and more behavioral and social problems throughout early development, than youngsters whose mothers ate 12 or more ounces per week.
Other studies suggest that missing out on the high levels of omega-3 fatty acids found in fish can increase the risk of delivering a baby too early and at a low birth weight.
It's not just babies and children who may be harmed by inadequate consumption of seafood. Women who do not get enough omega-3s in pregnancy seem to have a higher risk of depression while expecting and after giving birth. Postpartum depression afflicts about one of every 10 new mothers, said James McGregor, a University of Southern California obstetrician who headed the Maternal Nutrition Group, which drafted the new guidelines.
Some countries and governmental groups, including the United Kingdom, Australia, Belgium, the Netherlands and the Nordic Council of Ministers, already advise that pregnant women eat at least two servings of fish per week.
The latest recommendations add to a growing call for consuming more omega-3 fatty acids during pregnancy. The Healthy Mothers guidelines say it is best to choose ocean fish, such as salmon, tuna and sardines, which are highest in omega-3s.
Fish is rich in selenium, a mineral that occurs at about five to 20 times the concentration of mercury. When the two chemicals bind, "there is a growing body of evidence that selenium in ocean fish may also counteract the potential negative influence of mercury exposure," the panel said.
An FDA representative said that the agency "plans to study the recommendations" but has not changed its advice.
For women who don't like fish -- or feel caught in the middle of the scientific debate -- options include other food rich in omega-3s such as flaxseed and oil, or foods fortified with omega-3s, such as eggs from chickens raised on feed rich in DHA.
Fish oil supplements are another choice. Earlier this year, the European Commission recommended that pregnant and lactating women take 200 milligrams per day of DHA supplements.