Here’s How Much Tuna You Can Safely Eat
Fish is an excellent source of protein, omega-3 fatty acids and other essential nutrients. It is also one of the staples of the famous healthy Mediterranean diet . But fish can contain mercury, and some types of tuna are known to be high in mercury. So how much is too much?
The FDA sets guidelines for children and pregnant adults.
The FDA has a nutritional recommendation chart for children (under 12) and for those who are pregnant or breastfeeding. If you do not fit into these categories, it does not set specific limits or recommendations for preventing mercury from entering fish. (The one exception is that they also suggest following the advice before you get pregnant if you plan on doing so, since mercury stays in your body for a while.)
For adults, the FDA Dietary Guidelines recommend eating at least eight ounces per week to realize the benefits of eating fish. If you’re pregnant, the recommendation is a little more specific: eight to 12 ounces of low-mercury fish; more than that and you could end up with too much mercury. A five ounce can of tuna contains four ounces of fish (the other ounce is water or oil).
The FDA also has a list of high, medium, and low mercury fish based on tests.
- Canned “light” tuna is low in mercury (so you can eat up to three cans a week if you’re pregnant, if that’s the only fish you eat)
- Canned skipjack tuna is also low in mercury.
- Albacore or “piece of white” tuna is on the list for medium mercury content.
- Yellowfin is also on the list with medium mercury.
So if you’re an adult who is n’t pregnant (and doesn’t plan on getting pregnant), you can officially eat as much tuna as you want, but you may prefer lower mercury options. If you are pregnant , planning to become pregnant, or are breastfeeding, you are advised to consume light tuna or other low-mercury fish.
Some cans of tuna have more mercury than others
Are recommendations good enough to keep us safe? There is no clear answer to this question because the recommendations contain judgment. If you’re concerned about mercury, you might decide to eat a lot less fish (maybe even drop the eight-ounce minimum). There are also people who eat albacore every day for lunch – maybe not a good idea, but if you’re an adult, it would take a lot of mercury to harm you. The emphasis is on pregnancy and children, as mercury can have detrimental effects on the brain, heart, and blood vessels of a growing child.
Consumer Reports recently tested the levels of mercury in cans of tuna and came up with its own set of recommendations. They are not backed up by government guidelines or much evidence, but are also the judgment of the people at Consumer Reports. They recommend that people who are not pregnant eat no more than one to two cans of albacore per week, depending on the brand, but up to three cans per week of most brands of light tuna is perfectly acceptable. In their tests, Chicken of the Sea, Safe Catch and Starkist showed lower levels of mercury.
Consumer Reports recommends avoiding tuna entirely if you’re pregnant because some cans have unpredictably higher levels of mercury than others. But that doesn’t mean that other types of fish are safer; they did not test tilapia, salmon, or other FDA-listed low mercury fish for comparison. Avoiding low-mercury fish during pregnancy means avoiding fish entirely, which is also not in line with FDA guidelines.
The Consumer Reports view strikes me as somewhat exaggerated. I would prefer recommendations from a government agency that has tested a large number of fish and made recommendations that balance the risks and benefits, rather than random tests of one publication and citations from several experts. But like I said before, it’s a judgment anyway. If you eat tuna sticking to “light” instead of albacore, you’re more likely to lower your mercury levels.