Edward C. Geehr, M.D.

Pregnant and breastfeeding moms no longer need to avoid fish.

In a complete reversal from 2004 guidelines, the Food and Drug Administration is now calling on pregnant women to eat more fish. For the past 10 years, the FDA recommended that pregnant women and children largely avoid seafood due to mercury contamination that can interfere with nervous system development.

The FDA now says that limiting or avoiding fish during pregnancy and early childhood can deprive developing brains and bodies of important nutrients.

The new guidelines recommend eating 8-12 ounces of a variety of seafood each week from low-mercury fish – trout, snapper, crab, sardines, salmon and whitefish. That amounts to 2 or 3 servings of fish per week for women who are pregnant, might become pregnant or are breastfeeding. Fish has high nutritional value during fetal growth and development before birth, in early infancy for breastfed infants, and in childhood.

Children are encouraged to eat 2 or 3 servings of fish per week, with portion sizes adjusted for age and calorie needs.

White (albacore) tuna should be limited to 6 ounces per week due to higher mercury content, compared to light canned tuna.

Fish to be avoided include tilefish from the Gulf of Mexico, shark, swordfish and king mackerel. When eating fish caught from streams, rivers and lakes, consumers should pay attention to local advisories concerning possible naturally occurring or industrial contamination. The FDA recommends that if advisories are not available, adults should limit freshwater fish consumption to 6 ounces per week and young children to 1-3 ounces per week. Then do not eat other fish that week.

The FDA decided to issue the advisory after recent reports showed many pregnant women in the U.S. were not eating fish in amounts recommended by its Dietary Guidelines for Americans 2010 – at least 8 ounces and up to 12 ounces of a variety of seafood per week, from choices lower in methylmercury.

An analysis of more than 1,000 pregnant women found that 21% ate no fish during the month before the survey and the remainder consumed far less fish than recommended.

Mercury occurs naturally in the environment and can be released through industrial activities. It collects in streams, lakes and oceans and is converted to methylmercury in the water. It is this form of mercury that is found in fish. Most fish contain some methylmercury, and it tends to accumulate more in certain types of fish than others, especially in larger fish with longer life spans.

Methylmercury is a neurotoxin that can be harmful in relatively small amounts to the developing brain and nervous system. In the FDA's judgment, the dietary guidelines will minimize the potential harms from methylmercury, while still reaping the nutritional benefit from fish consumption.

Fish are sources of high-quality protein, vitamins, minerals and omega-3-fatty acids. They are mostly low in saturated fat and some even contain vitamin D. These nutrients are particularly important during a child's early development phases of growth. Benefits can include, according to the FDA, higher IQ scores among children of women who eat fish.

Based on the available information, the FDA's guidelines seem to strike a reasonable balance between potential harms of minute amounts of methylmercury and the nutritional benefits of fish as part of a balanced diet.