Selenium is a potent antioxidant that protects every cell in your body. Antioxidants, like selenium, neutralize damaging free radicals that destroy normally healthy cells and increase your risk of illness. Even though you need selenium to keep your body in tip-top shape, too much can be toxic. If you're taking a selenium supplement, or even a daily multivitamin, inform your doctor.
You can safely have up to 400 micrograms of selenium per day, which is the established tolerable upper intake level, or UL, for this mineral, according to the Linus Pauling Institute. While you are unlikely to reach this level through your diet alone, you may exceed this amount when you take over-the-counter supplements. Whether you consume a large dose all at once or continuously exceed your recommendation over a period of time, too much selenium can be extremely toxic.
Selenium toxicity is known as selenosis. Some of the initial warning signs of this condition are physical symptoms. In the beginning, your hair becomes brittle and may fall out in clumps. Your nails might also appear white and blotchy and break easily. As selenosis progresses, you'll probably have bad breath that mimics the odor of garlic. In severe cases, bright red patches can form all over your body, which may or may not be itchy.
Some of the results of selenosis may not be so obvious. For example, too much selenium causes fatigue and irritability, which are symptoms that are attached to many conditions, including your monthly cycle. Excessive selenium affects your digestive tract, possibly causing abdominal cramping, diarrhea, bloating or constipation. In more severe cases, selenosis takes a toll on your central nervous system. You may experience poor balance, an inability to concentrate or numbness and tingling in your limbs. If left untreated, selenium toxicity can be fatal.
Proper Dose and Food Sources
From the age of 14 and throughout adulthood, men and women need 55 micrograms of selenium each day. During certain stages, women may need even more. While you are pregnant, your recommendation goes up to 60 micrograms. If you breastfeed after your little one is born, you'll need 70 micrograms of selenium, reports the Office of Dietary Supplements. Shrimp, crab, salmon, halibut and pork each provide between 30 and 40 micrograms per 3-ounce serving. Some varieties of enriched noodles have nearly 40 micrograms per 1-cup cooked portion, whole-wheat bread offers about 12 micrograms per slice and brown rice has almost 20 micrograms of selenium per 1-cup cooked serving.
Most foods have moderate levels of selenium, however, there is one exception. Limit Brazil nuts in your diet, since they have more than 540 micrograms of selenium in just six kernels. You may unknowingly consume excessive amounts of selenium if you do not measure out your serving ahead of time.
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