By Sally Squires
Tuesday, February 20, 2007
Pregnant and nursing women, as well as those who want to conceive, are advised in the United States to avoid certain types of seafood and to limit consumption of other varieties as a way to reduce potential ill effects from mercury and other contaminants.
But a new report from a huge, ongoing research project in the United Kingdom suggests that if women skimp on seafood during pregnancy it may be detrimental to their children.
Feeling a bit like a fish that flip-flops out of water?
Conflicting nutrition advice can be confusing, particularly for pregnant women, who often feel that they must become nutritional experts overnight as they start to eat for two. Just ask Eric Rimm, professor of epidemiology and nutrition at the Harvard School of Public Health, whose female relatives were so worried about the reports of contaminants in fish that they were ready to give up all seafood when they became pregnant. "I said, 'No, no, no, you have to eat fish,' " Rimm relates. "There's so much more benefit than risk."
The latest findings, published last week in the journal the Lancet, confirm his advice. Drawn from the Avon Longitudinal Study of Parents and Children (ALSPAC), a project involving about 14,000 women and their kids, they show that the benefits of eating most types of seafood during pregnancy far outweigh any risks.
What surprised scientists most is that women who ate 12 ounces or less of seafood per week -- the amount that pregnant and nursing mothers are advised to stick to by the Food and Drug Administration and the Environmental Protection Agency -- "were almost 50 percent more likely to have children with low verbal IQ scores compared with women who exceeded the advisory," says Joseph R. Hibbeln, a researcher at the National Institute on Alcohol Abuse and Alcoholism and co-author of the report.
At age 3, children whose mothers ate less seafood during pregnancy were more likely to have social and communication problems with their peers, Hibbeln says. By ages 7 and 8, they tended to have more behavioral problems and trouble with fine motor skills and were more likely to have lower academic scores, Hibbeln says.
Indeed, skimping on seafood during pregnancy appears to produce the very problems that scientists feared could occur from eating too much seafood containing mercury. "Advice to limit seafood consumption could actually be detrimental," concludes the study's team, which includes scientists from the University of Bristol.
The ALSPAC report is the third in recent years to find few or no adverse effects from consuming most types of seafood during pregnancy.
Will the current advice change? That's not yet known. The EPA and the FDA still have to review the latest findings. And some scientists, including Rimm, think that it's too soon to do more than reword the advice so women understand that 12 ounces per week is a goal, not a limit. That way, he says, women won't "think that they should be eating zero to 12 ounces per week."
Here's a sampling of the latest nutritional advice for women who are pregnant, nursing or planning to conceive:
Choose seafood lowest in mercury. The more variety, the better. Don't sweat the nutritional consequences of wild vs. farmed fish. A recent Harvard School of Public Health report showed that farm-raised fish contains as much, if not more, healthy omega-3 fatty acids as wild species do. Good choices include salmon, herring, sardines, anchovies, catfish, shrimp and light tuna. Skip shark, swordfish, king mackerel and tilefish (found mostly in Hawaii).
Limit albacore tuna to six ounces per week. This large species is highest in mercury, which is why there is widespread agreement that it should be avoided by women of childbearing ages and by young children. Also skip fried fish, especially from fast-food restaurants. It contains few omega-3 fatty acids and may have unhealthy trans fats.
Avoid raw fish, steak tartare and any other raw meat, poultry and dairy products. That means sushi, clams on the half shell, prosciutto, lox, smoked meats and various meat jerkies. All can be sources of listeria, a bacteria that sickens about 2,500 people annually and is particularly dangerous for pregnant women and their fetuses. For the same reason, skip refrigerated pâté and other meat spreads, as well as unpasteurized dairy products. These include cheeses made from raw, unpasteurized milk such as brie, Camembert, feta, blue cheese and queso blanco (as well as Mexican-style soft cheeses).
Eat these foods "only if the package says they are made from pasteurized milk," advises W. Allan Walker, director of Harvard Medical School's Division of Nutrition and author of "The Harvard Medical School Guide to Healthy Eating During Pregnancy" (McGraw-Hill, $16.95). Skip them at restaurants where you can't be sure they are from pasteurized milk, Walker advises.
Abstain from alcohol. There is no safe level for pregnant women. At Lucile Packard Children's Hospital in Palo Alto, Calif., registered dietitian Trudy Theiss advises women trying to conceive to be teetotalers, because it takes at least a couple of weeks to confirm a pregnancy.
Reheat deli meats and hot dogs. Make sure they are steaming hot, Theiss advises, so that they reach a temperature of about 160 degrees, the level needed to kill listeria and other bacteria.
Go easy on the caffeine. Up to 300 milligrams per day seems to be safe, Theiss notes. That's the amount found in one or two small cups of coffee.
And if you like your beverages sweet but don't want added sugar, choose sugar substitutes wisely. Splenda does not seem to cross the placenta, Walker says, making it a safe choice for pregnant women who want to use a sugar substitute.
But skip saccharin, a sweetener that is a weak carcinogen, as well as stevia, which is sold as a dietary supplement but has not been approved as a food ingredient by the FDA. Also go easy on aspartame, sold as NutraSweet and Equal, since the FDA sets daily levels based on body weight.