Two federal agencies have revised the 2010 Dietary Guidelines for Americans with a recommendation that women in their childbearing years and children should eat more fish.

The United States Food and Drug Administration and U.S. Environmental Protection Agency announced today "pregnant and breastfeeding women, those who might become pregnant, and young children should eat more fish that is lower in mercury in order to gain important developmental and health benefits," according to an FDA news release.

The two agencies had previously offered advice on the maximum amounts of fish women and kids should eat, but didn't specify a minimum amount.

Added research over the past decade, however, has emphasized the importance of appropriate amounts of fish to promote positive physical growth and health.

"For years many women have limited or avoided eating fish during pregnancy or feeding fish to their young children," said Stephen Ostroff, the FDA's acting chief scientist. "But emerging science now tells us that limiting or avoiding fish during pregnancy and early childhood can mean missing out on important nutrients that can have a positive impact on growth and development as well as on general health."

An analysis of seafood consumption data from over 1,000 pregnant women in the U.S. found 21 percent of them ate no fish in the previous month.

The study 50 percent of the women surveyed ate fewer than 2 ounces of fish a week, while 75 percent ate fewer than 4 ounces a week. The draft updated advice recommends pregnant women weekly eat between 8 and 12 ounces of a variety of fish that are lower in mercury, in order to support fetal growth and development.

"Eating fish with lower levels of mercury provides numerous health and dietary benefits," said Nancy Stoner, the EPA's acting assistant administrator for the Office of Water. "This updated advice will help pregnant women and mothers make informed decisions about the right amount and right kinds of fish to eat during important times in their lives and their children's lives."

The agencies' updated advice cautions pregnant or breastfeeding women against ingesting four types of fish associated with high mercury levels: tilefish from the Gulf of Mexico; shark; swordfish; and king mackerel. The draft recommendations also suggest limiting consumption of white (albacore) tuna to 6 ounces a week.

On the other hand, fish with lower levels of mercury include shrimp, pollock, salmon, canned light tuna, tilapia, catfish and cod.

It strongly recommended that, when eating fish caught from local streams, rivers and lakes, people should heed the warnings and dietary guidelines announced by local authorities; if that's not possible, the intake of such fish ought to be limited to 6 ounces a week for adults, 1-3 ounces per week for children.