Although tuna is an excellent source of dietary protein, omega-3 fatty acids, iodine, iron and B vitamins, eating too much canned tuna may pose health risks, especially for pregnant women, breastfeeding women and young children. However, because canned tuna is loaded with essential nutrients, you don’t have to avoid it entirely.
Canned tuna contains varying amounts of methylmercury, which is a known neurotoxin. Although your body slowly excretes mercury slowly over time, ingesting too much of it causes an accumulation of mercury in bodily tissues, such as your brain and kidneys. Symptoms of long-term mercury exposure include numbness in your skin, shakes or tremors, difficulty walking, vision problems, memory problems, seizures and fetal brain damage when ingested during pregnancy or through breast milk.
Bisphenol A Considerations
Bisphenol A, otherwise known as BPA, is a chemical in tuna cans that can potentially seep from the can into the tuna. The U.S. Food and Drug Administration reports that BPA potentially negatively affects behavior, the brain and prostate glands in infants, fetuses and young children. However, a 2014 study published in the ”Journal of Exposure Science and Environmental Epidemiology” found that although consuming school lunches, eating meals prepared outside the home and drinking soda does increase urinary BPA, eating canned tuna was not significantly associated with higher urinary BPA levels.
Although you can choose canned tuna without added sodium, many varieties of canned tuna are high in sodium. For example, a 3-ounce portion of canned light tuna packed in oil contains 354 milligrams of sodium. Consuming too much dietary sodium can cause high-blood pressure and increase your risk for developing heart disease. Choosing canned light tuna packed in water without added salt reduces the sodium content of canned tuna to 42 milligrams per 3-ounce portion. The American Heart Association recommends that adults limit sodium intake to less than 1,500 milligrams daily.
To reduce the risk of ingesting too much methylmercury, BPA and sodium from canned tuna, limit the amount you eat. Because of negative effects of methylmercury on fetal development, the American Pregnancy Association suggests pregnant women, those trying to become pregnant and children should avoid Ahi and bigeye tuna, eat no more than 18 ounces of canned white albacore tuna or yellowfin tuna per month and limit canned chunk light or skipjack tuna consumption to 36 ounces monthly.
- MedlinePlus: Mercury
- U.S. Food and Drug Administration: Bisphenol A (BPA): Use in Food Contact Application
- Journal of Exposure Science and Environmental Epidemiology: Daily Intake of Bisphenol A and Potential Sources of Exposure: 2005–2006 National Health and Nutrition Examination Survey
- USDA National Nutrient Database Release 26: Basic Report: 15119, Fish, Tuna, Light, Canned in Oil, Drained Solids
- USDA National Nutrient Database Release 26: Basic Report: 15184, Fish, Tuna, Light, Canned in Water, Without Salt, Drained Solids
- American Heart Association: Frequently Asked Questions (FAQs) About Sodium
- American Pregnancy Association: Mercury Levels in Fish