PRESCRIPTIONS
Pregnant women should avoid fish high in mercury

By Laurie Steelsmith

Q. I've heard that some kinds of fish contain mercury. Is it safe for me to eat fish while I'm pregnant? If so, which should I avoid and which kinds are safe to eat?

A. Fish is an excellent source of lean protein, vitamins and minerals. The fats in fish have proven to be beneficial in the development of an infant's retina and brain. They may also help prevent heart disease by promoting "friendly" HDL cholesterol and lowering "unfriendly" LDL cholesterol. However, fish can contain high levels of toxic chemicals, particularly mercury.

The U.S. Food and Drug Administration says that nearly all fish contain trace amounts of mercury in the form of methyl mercury, which is one of the element's most toxic forms. Fish absorb methyl mercury from the organisms they feed on, and it then becomes concentrated in their tissues. The older and larger the fish, the more methyl mercury it is likely to have. Predator fish tend to have more mercury than nonpredator fish.

The FDA has issued a warning to pregnant women and nursing mothers to avoid eating shark, swordfish, king mackerel and tilefish. These large fish can contain exceptionally high levels of methyl mercury, which could cause damage to a baby's developing nervous system and brain. Cooking does not destroy mercury, so it's a good idea to avoid feeding these fish to young children. Adults should not eat them regularly.

Tuna, the most popular seafood in the United States, has come under scrutiny by the FDA because some species can contain high levels of methyl mercury.

My patients often ask me where the mercury comes from. Some occurs naturally in the environment, but much of it comes from industrial and coal-burning power plants. The mercury is released into the air and concentrated in clouds. When it rains, the mercury ends up in ponds, rivers, the ocean and — eventually — in the fish we eat. Fish that are caught closer to industrial areas are more likely to have higher levels of mercury and other environmental contaminants.

What kind of fish is safe for you to eat while you are pregnant? According to the Environmental Working Group, fish found to be lowest in mercury include catfish, croaker, flounder, haddock, farmed trout and wild Pacific salmon. The FDA recommends that all fish consumption be limited to 12 ounces, or two servings, a week.

Laurie Steelsmith is a naturopathic physician and licensed acupuncturist in Honolulu. Send questions to: Prescriptions, Island Life, The Advertiser, P.O. Box 3110, Honolulu, HI 96802, or to islandlife@honoluluadvertiser.com. This column is for information only. Consult your health provider for medical advice.