Side Effects of Mercury in Tuna
Mercury, also known as methylmercury, is typically unavoidable when you eat most types of fish, including tuna. The substance forms in water as it reacts with specific types of bacteria. As the tuna fish swim along, their bodies absorb the mercury from the water. Your system should be able to flush out excess mercury on its own. But if you do experience side effects from mercury, the damage is irreversible. As long as you stop eating tuna and other high-mercury foods, the severity of the problems shouldn’t get any worse.
Loss of Certain Senses
Mercury can build up in your blood over an extended period of time. If you continuously consume mercury-rich tuna, you might gradually start having problems with your vision or hearing. You may have trouble focusing, see blurry objects or struggle to hear someone conversing with you from a close distance. As mercury continues to accumulate, in extreme cases, you could become completely blind or deaf.
- Mercury can build up in your blood over an extended period of time.
- If you continuously consume mercury-rich tuna, you might gradually start having problems with your vision or hearing.
Is Tuna Healthy to Eat?
As your mercury level goes up if you regularly consume tuna, you may start noticing some neurological abnormalities. You could lose your coordination, find it difficult to walk and have very tight muscles and stiff joints. Symptoms sometimes appear on one side of the body or in just one arm or leg. These are warning signs of cerebral palsy, a group of brain and nervous system disorders. Depending on the exact diagnosis, some types of cerebral palsy are associated with seizures, learning disabilities, difficulty speaking, irregular breathing, incontinence and hearing or vision problems.
- As your mercury level goes up if you regularly consume tuna, you may start noticing some neurological abnormalities.
- These are warning signs of cerebral palsy, a group of brain and nervous system disorders.
During periods of rapid growth, like during pregnancy, infancy or childhood, mercury is of great concern. Mercury can inhibit cellular division, leading to a halt in cell growth. Problems with neurological development and brain growth could form in your growing fetus or child. As a result, your little one may end up with an abnormally small head and possibly intellectual delay.
- During periods of rapid growth, like during pregnancy, infancy or childhood, mercury is of great concern.
- Problems with neurological development and brain growth could form in your growing fetus or child.
Tuna in Your Diet
Is Tuna Healthy?
Nearly all types of tuna contain some level of mercury. But white albacore tuna usually has up to three times as much mercury as canned light tuna. The U.S. Environmental Protection Agency recommends limiting yourself to no more than 6 ounces of albacore tuna weekly. Mercury levels in fresh-caught tuna steak depend on where it comes from, such as whether it is farm-raised or wild. Because tuna steak often has more mercury than canned light tuna, you should also limit yourself to just 6 ounces weekly. These strict recommendations are particularly important for children and women of childbearing age, although they're suggested for everyone to follow.
- Nearly all types of tuna contain some level of mercury.
Is Tuna Healthy to Eat?
Is Tuna Healthy?
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- MedlinePlus: Methylmercury Poisoning
- U.S. Environmental Protection Agency: What You Need to Know about Mercury in Fish and Shellfish
- Environmental Defense Fund: Mercury Alert: Is Canned Tuna Safe to Eat?
- MedlinePlus: Cerebral Palsy
- Natural Resources Defense Council: Mercury Contamination in Fish
- Fish, tuna, light, canned in water, without salt, drained solids. FoodData Central. U.S. Department of Agriculture. Published April 1, 2019.
- Dhurmeea Z, Pethybridge H, Appadoo C, Bodin N. Lipid and fatty acid dynamics in mature female albacore tuna (Thunnus alalunga) in the western Indian Ocean. PLOS ONE. 2018. doi:10.1371/journal.pone.0194558
- Vitamin B12 or folate deficiency anaemia. National Health Service. Updated 2019.
- Sparkes C, Gibson R, Sinclair A, Else PL, Meyer BJ. Effect of low dose docosahexaenoic acid-rich fish oil on plasma lipids and lipoproteins in pre-menopausal women: A dose⁻response randomized placebo-controlled trial. Nutrients. 2018;10(10). 10.3390/nu10101460
- Simonetto M, Infante M, Sacco RL, Rundek T, Della-Morte D. A novel anti-inflammatory role of omega-3 PUFAs in prevention and treatment of atherosclerosis and vascular cognitive impairment and dementia. Nutrients. 2019;11(10). doi:10.3390/nu11102279
- Damanti S, Azzolino D, Roncaglione C, Arosio B, Rossi P, Cesari M. Efficacy of nutritional interventions as stand-alone or synergistic treatments with exercise for the management of sarcopenia. Nutrients. 2019;11(9). doi:10.3390/nu11091991
- Diabetes superfoods. American Diabetes Association. Updated 2020.
- Histamine toxicity. American Academy of Allergy, Asthma & Immunology. Updated 2020.
- ACOG practice advisory: Update on seafood consumption during pregnancy. American College of Obstetricians and Gynecologists. Updated 2017.
- Canned tuna. Seafood Health Facts: Making Smart Choices Balancing the Benefits and Risks of Seafood Consumption. Updated 2020.
- Selecting and serving fresh and frozen seafood safely. U.S. Food and Drug Administration. Updated 2019.
Melodie Anne Coffman specializes in overall wellness, with particular interests in women's health and personal defense. She holds a master's degree in food science and human nutrition and is a certified instructor through the NRA. Coffman is pursuing her personal trainer certification in 2015.