Canned Tuna: What About Mercury?

Fish is one of the healthiest types of food you can eat. It’s a good source of protein, is low in saturated fat and contains omega-3 fatty acids, which are important for cardiovascular health. Eating canned tuna is probably the most convenient way to enjoy the health benefits of fish. You don’t have to fillet it or cook it. It’s easy to make a tuna sandwich or to carry a can of tuna to the office.

Unfortunately, canned tuna can contain large amounts of mercury; a toxin that can harm your brain, lungs, heart, kidneys and immune system. Mercury can affect the development of the brain and nervous system in fetuses, so women who are pregnant or planning to become pregnant should be particularly careful with mercury exposure. Mercury is also very dangerous to infants and small children.

Here’s how you and your family can get the benefits of eating tuna while reducing your exposure to mercury.

Go for canned light

Of the two main types of canned tuna – canned light and chunk white – canned light usually has much lower concentrations of mercury than chunk white does.

Most canned light tuna comes from skipjack tuna, while canned white tuna comes from albacore tuna. Skipjack tuna is smaller than albacore tuna. It matures more quickly and is lower on the food chain than albacore tuna, so there is less chance for mercury to bioaccumulate in its tissues.

Mercury builds up in fish through bioaccumulation. Tiny plants and other organisms that live in bodies of water take up mercury released in the atmosphere. Small fish eat these tiny organisms, taking up their mercury and allowing it to become more concentrated. Larger fish eat these smaller fish, and their mercury levels become even higher. The higher it is on the food chain, the more mercury a fish contains.

The FDA considers canned skipjack tuna to be low in mercury.

Skipjack tuna also tends to be less expensive than albacore and, unlike albacore, is not threatened by overfishing.

Always check the label carefully when buying canned light tuna. Some of it comes from yellowfin tuna, rather than skipjack tuna. Yellowfin tuna can have the same amount of mercury as albacore.

Have Your Kid Brown Bag It

If your child’s school allows students to bring their own lunches, give them a tuna sandwich or tuna salad, made with skipjack tuna, to bring to school, so they don’t have to eat the tuna that is served with school lunches. A 2012 U.S. government study showed that children who eat their school’s tuna twice a week could be exposed to six times the level of mercury considered safe according to federal guidelines.

Try Canned Salmon

Get out of the tuna habit and try canned salmon once in a while. It’s low in mercury and high in Omega-3s and vitamin D.

Make Time for Fresh Fish

While canned fish can be convenient, there are dangers to canned foods besides mercury. Like many canned foods, canned tuna can contain added salt, which can increase your risk of high blood pressure, heart failure, stroke, stomach cancer, kidney disease and osteoporosis. If you must buy canned tuna, always choose tuna with no added salt.

When you eat canned foods, you can expose yourself to Bisphenol A (BPA), a chemical that is often found in can linings and can disrupt your endocrine system.

To get your required Omega-3 intake, take the time to prepare fresh fish for yourself and your family once in a while. Eating a variety of types of fish, instead of just sticking with tuna, means exposure to more essential nutrients. Preparing your own food can give you the opportunity to experiment with adding healthy spices and other healthy ingredients, which will make eating more pleasurable.

Additional Sources:

EDF Seafood Selector: Salmon, Environmental Defense Fund

Mercury, Environmental Protection Agency

Omega-3 in fish: How eating fish helps your heart, Mayo Clinic

Tuna Lovers’ Dilemma: To Eat or Not to Eat, National Geographic

What You Need to Know about Mercury in Fish and Shellfish, Environmental Protection Agency