Fish Consumption: How much is good to eat?
Fish provides beneficial protein, essential nutrients and omega-3 fatty acids which are all important for your health. For pregnant women, it is important for the growth and development of your baby (particularly of the brain*). Some studies have found that women who eat fish during pregnancy have better pregnancy outcomes than women who do not eat fish.
Methylmercury is a toxic form of mercury found in the environment. You can be exposed to it by eating contaminated fish. Fish that are large, have long life spans, and eat other fish are more likely to contain higher amounts of methylmercury than small fish. The following large fish have the highest levels of methylmercury, and should be avoided during pregnancy: shark, swordfish, king mackerel, and tilefish.
Food and Drug Administration (FDA) advises pregnant women, women who are planning to become pregnant within one year, nursing mothers, and children under the age of 6 years to avoid fish that contain high levels of methylmercury. ***
FDA suggests that you may safely eat 12 ounces a week (340 grams, or two average meals) of most types of cooked fish. One week's consumption of fish probably would not greatly change the level of methylmercury in your body. If you eat a lot of fish during one week, you can limit your fish consumption for the next week or two.** You may also eat at least 8 and up to 12 oz per week (4 oz serving = approx. a deck of cards & 6 oz serving = approx. size of a check book) of low-mercury fish: salmon, Pollack, shrimp, canned light tuna (limit albacore tuna and tuna steak to one 6 oz serving per week) and catfish
* Methylmercury crosses the placenta and can be found in the baby’s blood at levels higher than those in the mother. The baby’s brain is the most sensitive organ to the effects of methylmercury exposure. The brain continues to develop throughout the entire pregnancy, so exposure at any time in pregnancy may be of concern. The birth defects seen were small head size, cerebral palsy, developmental delay and/or mental retardation, blindness, muscle weakness, and seizures.
** The amount of time it takes to remove half of the body’s methylmercury stores is approximately 70 to 80 days.
*** Studies in experimental animals have shown that mercury can change the shape and movement of sperm. In humans, the research data are not clear. Some studies have suggested that high levels of mercury may cause infertility while other studies have not. There is no information suggesting that a father’s exposure to methylmercury can cause birth defects or mental retardation in his children.
Things to avoid when pregnant:
- High-mercury fish: swordfish, shark, mackerel, tilefish and other large predatory species.
- Raw fish & shellfish
- Refrigerated smoked fish (salmon – nova lox)
Locally caught fish
Fishing is a wonderful way to enjoy the beautiful landscape and weather here in Utah. It is good practice to always check the environmental reports on the mercury levels of local waterways before consuming fish caught in them. Up-to-date mercury advisories for local bodies of water can be found at www.fishadvisories.utah.gov.
Tips to use in your kitchen
- Cook seafood to an internal temperature of at least 145 F (use a clean meat thermometer to check the temperature in the center of the fish). The fish should flake easily and have an opaque appearance.
- If shellfish (clams, mussels, oysters) does not open naturally in the cooking process, discard that particular piece and do not eat it.
- Alternative sources of omega-3 fatty acids: Although low-mercury containing fish are the best source of omega-3 fatty acids, they can also be found in flax seeds, walnuts and olive oil.
- Things to keep in mind about mercury:
- Alternative sources of contamination: broken thermometers and light bulbs. Always dispose of these items carefully and safely.
- For additional information on mercury levels of local waterways, safely consuming fish and proper disposal of mercury-containing items call the Department of Environmental Hotline 1-800-458-0145 or visit www.mercury.utah.gov