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.

Tuna on a bed of pasta.
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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.

Neurological Problems

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.

Growth Issues

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.

Tuna in Your Diet

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.

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