Fish and Mercury: What You Need to Know

by | Updated: December 3rd, 2016 | Read time: 2 minutes

Before you order a tuna salad sandwich for lunch, consider the following: certain fish contain high levels of mercury, a chemical known to cause serious health problems, especially for pregnant women and children.

In 2004, the Environmental Protection Agency (EPA) issued recommendations regarding exposure to mercury in fish and shellfish. The EPA noted that although fish contains high-quality protein and other essential nutrients, such as omega-3 essential fatty acids, it also contains traces of mercury that may harm an unborn baby or young child’s developing nervous system.

Mercury occurs naturally in the environment, but it’s also released into the air by industrial pollution. It falls into the ocean and other waterways and turns into methylmercury, a harmful chemical. Fish absorb it, and it builds up in their bodies over time. Some fish end up with higher levels than others, depending on what they eat.

The EPA advises that pregnant women, women who may become pregnant, nursing mothers and young children avoid some types of fish and instead choose others that are low in mercury. Here are their guidelines:

“¢Do not eat shark, swordfish, king mackerel or tilefish because they contain high levels of mercury.  
Eat up to 12 ounces (2 average meals) a week of a variety of fish and shellfish that are lower in mercury.
“¢ Five of the most commonly eaten fish that are low in mercury are shrimp, canned light tuna, salmon, pollock and catfish.
“¢ Another commonly eaten fish, albacore (“white”) tuna has more mercury than canned light tuna. So, when choosing your two meals of fish and shellfish, you may eat up to 6 ounces (one average meal) of albacore tuna per week.
“¢ Check local advisories about the safety of fish caught by family and friends in your local lakes, rivers and coastal areas. If no advice is available, eat up to 6 ounces (one average meal) per week of fish you catch from local waters, but don’t consume any other fish during that week.

Another way to obtain the health benefits (namely, omega-3 essential fatty acids) of eating fish is to take a fish oil supplement. Just be sure the product has been molecularly distilled, a process which removes mercury and other contaminants from the fish oil.