Pregnancy and fish: What's too little — or too much?

Is it safe to eat fish during pregnancy — or is it riskier not to? A Mayo Clinic specialist offers practical advice about pregnancy and fish.

If you're pregnant, you may feel that you need to become a nutrition expert overnight. After all, what you eat and drink — and what you avoid — influences your baby's development. Some choices are logical, such as plenty of fruits and vegetables and no alcohol. But what about fish and other types of seafood? Researchers give mixed reports.

Here, Roger Harms, M.D., a pregnancy specialist at Mayo Clinic, Rochester, Minn., and medical editor-in-chief of MayoClinic.com, offers practical advice about pregnancy and fish.

What's the link between pregnancy and fish?

Seafood can be a great source of protein and iron — crucial nutrients for your baby's growth and development. And the omega-3 fatty acids in many fish can help promote your baby's brain development. In fact, a British study published in February 2007 suggests that skimping on seafood during pregnancy may contribute to poor verbal skills, behavioral problems and other developmental issues during childhood.

But some types of seafood — particularly large, predatory fish such as swordfish, shark, king mackerel and tilefish — contain potentially high levels of mercury. Although the mercury in seafood isn't a concern for most adults, special precautions apply if you're pregnant or planning to become pregnant. During pregnancy, too much mercury may damage your baby's developing brain and nervous system.

What's safe to eat?

Some types of seafood contain little mercury. The Food and Drug Administration (FDA) says pregnant women can safely eat up to 12 ounces a week (two average meals) of:

Shrimp
Canned light tuna (limit albacore tuna and tuna steak to no more than 6 ounces a week)
Salmon
Pollock
Catfish

But some scientists suspect that these limits are too low. In the British study, women who ate 12 ounces or less of seafood a week were more likely to have children with verbal or other communication problems at age 3, and behavioral problems and trouble with fine motor skills by ages 7 and 8. No negative effects were noted for women who ate more seafood than the FDA-approved guidelines.

Are there other guidelines for pregnancy and fish?

To reduce your exposure to mercury, don't eat shark, swordfish, king mackerel or tilefish. To avoid ingesting harmful bacteria or viruses, avoid raw fish and shellfish — especially oysters and clams — and anything caught in polluted water. Refrigerated smoked seafood also is off-limits, unless it's an ingredient in a casserole or other cooked dish.

If you eat fish from local waters, pay attention to local fish advisories. Larger game fish contaminated with chemical pollutants may have the potential to harm a developing baby. If no advice is available, limit consumption of fish from local waters.

Most fish should be cooked to an internal temperature of 145 F. The fish is done when it separates into flakes and appears opaque throughout. Cook shrimp, lobster and scallops until they're milky white. Cook clams, mussels and oysters until their shells open. Discard any that don't open.

Are fish oil supplements safer than fresh or frozen fish?

In a study published in December 2006, children of mothers who took fish oil supplements during pregnancy had better hand-eye coordination at age 2 1/2 than did children whose mothers didn't take fish oil supplements during pregnancy. However fascinating, the findings are preliminary. There's still much to be learned about fish oil supplements during pregnancy.

It's important to keep in mind that fish oil supplements aren't uniformly tested for the presence of mercury. Supplements derived from algae rather than fish may be less likely to contain contaminants, but the safety of fish oil supplements during pregnancy has yet to be established. More studies are needed before fish oil supplements can be routinely recommended during pregnancy.

What's the bottom line?

Mercury is a serious cause of congenital abnormalities in babies, but average consumption of seafood containing low levels of mercury hasn't been shown to cause problems in babies. And the omega-3 fatty acids in many types of fish — especially salmon and tuna — promote healthy fetal development. As long as you avoid fish known to be high in mercury or contaminated with pollutants, fish can be a regular part of your healthy-eating plan.

Source:

http://www.mayoclinic.com/

Posted by Ashiya Mizuki