My wife and I are trying to have a baby. We are concerned about our mercury intake. What foods and fish are high in mercury? What are safe levels?

-Paul from Maryland

Mercury is a naturally occurring environmental element that is released into the air through industrial pollution. Mercury from air accumulates in streams and oceans. Bacteria in the water causes chemical changes that transform mercury into methylmercury. Fish absorb methylmercury as they feed in these waters. Methylmercury builds up more in some fish than others depending upon what they eat, their lifespan and position on the food chain, etc. Fish and shellfish are the main sources of methylmercury exposure. 

Healthy adult males are at little risk for complications associated with consuming too much methylmercury; the benefits of eating fish far outweigh the risks. Depending on the amount and type of fish consumed, it may be prudent to modify your diet if you are planning to become pregnant, are pregnant, or are nursing. With simple adjustments, you can enjoy the health benefits of eating fish while reducing your unborn child's exposure to the harmful effects of methylmercury. 

With this in mind, the Food and Drug Administration (FDA) and the Environmental Protection Agency (EPA) designed an advisory to keep an individual's mercury consumption below harmful levels. Follow these same recommendations when feeding fish to your child but serve smaller portions:

• Don’t eat shark, swordfish, king mackerel or tilefish; they are high in mercury.

• Eat up to 12 ounces weekly of a variety of fish/shellfish that are low in mercury.
• Eat fish/shellfish low in mercury, examples include shrimp, salmon and pollock.
• Albacore ("white") tuna contains more methylmercury than canned light tuna. Limit albacore tuna; choose light tuna instead.
• Use care when eating fish caught in local lakes, rivers, etc. Check local advisories about the safety of fish caught in these areas. If information is not available on the methylmercury level of locally caught fish, eat less than 6 ounces per week; don't consume any other fish during that week. 

Nutrition experts recommend that consumers eat a balanced diet, choosing a variety of foods including fruits and vegetables, foods that are low in trans fat and saturated fat, as well as foods rich in high fiber grains and nutrients. Fish and shellfish can and should provide low-fat, nutritious protein sources in our diet. Since July 2002 the FDA has tested over 3400 cans of tuna and 227 fish samples (12 different species) for mercury. The FDA will continue to sample fish/shellfish for mercury on a regular basis. 

For further help of safety tips when buying fish see the following article from TheDietChannel: Fish Safety and Buying Guide. 

 

References:

 

“What you need to Know About Mercury in Fish and Shellfish.” Accessible online at: http://www.epa.gov/waterscience/fishadvice/advice.html.

 

“Mercury in Fish: Cause for Concern? U.S. Food and Drug Administration. FDA Consumer magazine, September 1994. Available online at: http://www.fda.gov/fdac/reprints/mercury.html.

Michèle Turcotte, MS, RD/LDN Contributing Expert

Have a question for our Experts? Send it in!