Other issues of Nutrition Advisor

Mercury Rising

You've probably heard about the benefits of eating fish, ranging from heart health to wrinkle-free skin. But before you dive in for this high protein, omega-3 fatty acid-rich food, there a few things to know about a particular mineral that may also swim with the sea's bounty.

How does mercury make its way into fish?
Mercury (Hg) is a mineral that occurs naturally in the environment. This diagram shows how mercury can make its way from the environment to your dinner plate.

Is mercury in fish a concern?
Just about all fish contain very small amounts of methylmercury—amounts which are not dangerous. However, several types of fish, especially those that are larger and live longer, pose the highest threat.

Consumption of fish high in methylmercury level can potentially lead to mercury poisoning. Symptoms may vary, but numbness and tingling sensations around the lips, fingers and toes usually are the first symptoms. Progressive symptoms may develop as a result of a gradually damaged nervous system.

Populations that are at high risk for mercury toxicity include pregnant and nursing women and children under the age of six. Mercury can pass through the placenta causing permanent damage to the developing brain of the fetus. Mercury may also cause damage to the developing brain of children; both can eventually lead to learning deficiencies and delayed mental development in children.

What can you do to prevent mercury poisoning?
Cooking does not help to reduce the methylmercury content of fish, but methylmercury does not stay in our bodies forever. Our bodies can eliminate methylmercury in an average of 50 days. Therefore, the best way to prevent mercury poisoning is to monitor your intake of those fish that are relatively high in mercury content.

Mercury Content in Various Fish Species

The Food and Drug Administration (FDA) recommends that pregnant and nursing women and young children should avoid fish with a high mercury content. A variety of cooked fish with lower mercury content is encouraged up to 12 ounces per week.

Source: FDA Consumer Advisory About the Risks of Mercury in Fish, March 2001.

In addition to the type of fish, source is very important also. Fish caught in local, fresh water lakes can be contaminated and unsafe to eat. Check with the Environmental Protection Agency or your state or local health department for the most current information about fish caught in your area.

The Yale-New Haven Nutrition Advisor is created by registered dietitians and dietetic interns who staff the Nutrition Clinic at Yale-New Haven Hospital. For information, contact the Nutrition InfoLine at (203) 688-2422.

For more information on this topic, you could visit:

• Consumer advice: SeafoodGateway to Government Food Safety Information
• Mercury, U.S. Environmental Protection Agency
• Consumer advisory: An important message for pregnant women and women of childbearing age who may become pregnant about the risks of mercury in fish, Center for Food Safety and Applied Nutrition, U.S. Food & Drug Administration, March 2001
• Seafood information and resources, Center for Food Safety and Applied Nutrition, U.S. Food & Drug Administration

Other issues addressed by Yale-New Haven Nutrition Advisor:

• A powerful B vitamin: Folate
• Vegging out
• Manic for organic
• Beta carotene
• Shellfish & cholesterol
• Sorting through nutrition information
• Summer fruit sensations
• Make it fun in the sun (outdoor food safety tips)
• Eat any sugar alcohol lately?
• Creating a garden rich in antioxidants
• Food safety in the kitchen
• Chocolate

Last revised: March 10, 2005 (jj)

Home page URL: http://www.ynhh.org

All information is intended for your general knowledge and is not a substitute for medical advice or treatment for specific medical conditions. You should seek prompt medical care for any specific health issues and consult your physician before starting a new fitness regimen.