In severe cases, acute selenium toxicity can lead to serious intestinal and neurological symptoms, heart attack, kidney failure, and death Summary While selenium toxicity is rare, overconsumption of this mineral through diet or supplements can have dangerous side effects.

It plays a critical role in metabolism and thyroid function and helps protect your body from damage caused by oxidative stress. This micronutrient can be found in a wide variety of foods, from oysters to mushrooms to Brazil nuts.

Our experts continually monitor the health and wellness space, and we update our articles when new information becomes available. Selenium is an important mineral for many body functions. Learn more about the signs of selenium deficiency and why it might become a bigger health….

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Learn about 20 selenium-rich foods, from lean meats to fruits and vegetables. MindBodyGreen provides third-party-tested supplements made with high quality ingredients.

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Some athletes may benefits from vitamin supplements. A Quiz for Teens Are You a Workaholic? How Well Do You Sleep? Health Conditions Discover Plan Connect. Nutrition Evidence Based 7 Science-Based Health Benefits of Selenium.

By Jillian Kubala, MS, RD — Updated on February 6, Acts as a powerful antioxidant. Share on Pinterest. May reduce your risk of certain cancers. May protect against heart disease. Helps prevent mental decline.

Is important for thyroid health. Boosts your immune system. May help reduce asthma symptoms. Best dietary sources of selenium. Dangers of excessive selenium intake. The bottom line. Selenium in global food systems. British Journal of Nutrition. Pophaly SD, Poonam SP, Kumar H, Tomar SK, Singh R.

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The evidence on taking selenium to treat heart disease is mixed. Scientists know that low levels of selenium can contribute to heart failure, and being deficient in selenium seems to make atherosclerosis worse. Atherosclerosis, or hardening of the arteries, happens when plaque builds up in arteries, which can lead to heart attack and stroke.

Studies show that taking selenium supplements does not seem to have any effect on the progression of heart disease, nor does it protect against heart attack. Selenium, combined with other antioxidants, including vitamin E and beta-carotene, may help lower LDL bad cholesterol levels.

But selenium can also interact with cholesterol-lowering drugs, and make them less effective. If you have or are at risk for heart disease, talk to your doctor before taking selenium.

Studies show that low levels of selenium are associated with a higher risk of cancer death. Scientists are not sure how selenium affects this risk. But they have observed that people who live in parts of the world where the soil is rich in selenium have lower rates of cancer, possibly because there is more selenium in food.

In addition, people who have cancer often have low levels of selenium. For most types of cancer, selenium does not appear to have much effect.

One early study looking at whether selenium reduced the risk of skin cancer found that, although it did not seem to affect skin cancer risk, people who took selenium lowered their risk of death from cancer overall. However, later studies found that selenium does not seem to lower the risk of lung or esophageal cancer.

Evidence is mixed on whether it protects against colorectal cancer. Two studies suggest that mcg per day might help protect against colorectal cancer, but other studies do not show any benefit. The best evidence suggests that if you have low levels of selenium, getting more selenium in your diet may lower your risk of prostate cancer.

Taking a special kind of selenium-rich brewer's yeast, called selenized yeast, may also help. In one study of 1, people, those who took mcg of selenium as selenized yeast per day compared to those who took a placebo had two-thirds lower risk of developing prostate cancer during the 4.

However, the men who got the benefit had low levels of selenium to start with. The situation is even more complicated when it comes to skin cancer. Some early evidence led scientists to investigate whether selenium might protect against skin cancer.

But a large trial found that taking daily selenium supplements actually increased the risk of squamous cell carcinoma and non-melanoma skin cancer.

Many studies suggest that the body needs selenium for the immune system to work properly. Selenium, along with other minerals, can help boost white blood cells, which improves the body's ability to fight illness and infection. A few studies suggest that selenium might help prevent some infections, such as a bacterial skin infection that often occurs with lymphedema, and mycoplasma pneumonia.

In addition, one study suggested that when elderly people took zinc and selenium supplements, their immune systems responded better to the flu vaccine than those who took placebo.

Evidence suggests that people with asthma tend to have low blood levels of selenium. In a study of 24 people with asthma, those who took selenium supplements for 14 weeks had fewer symptoms compared to those who took placebo.

But in a larger randomized, double-blind study, people who took a yeast supplement that contained selenium didn't have fewer symptoms than those who took placebo. More studies are needed. Studies have shown that levels of selenium go down consistently as HIV progresses.

In one study, those taking a particular selenium supplement called Selenomax slowed the increase in viral load and had higher CD4 cell counts.

But another study found that taking selenomethionine, a type of selenium, had no effect. If you have HIV or AIDS, talk to your doctor before taking any supplement, as it may interact with medications you are taking.

Selenium and other antioxidants play an essential role in how your body makes certain proteins found in sperm. One study suggested that selenium supplements might improve male fertility in men who had low levels of selenium.

However, high levels of selenium may negatively impact sperm's ability to swim. Low levels of selenium in the blood may be associated with increased risk of RA. But it does not seem that selenium supplements help once you have RA.

Good sources of selenium include brewer's yeast and wheat germ, liver, butter, fish mackerel, tuna, halibut, flounder, herring, and smelts , shellfish oysters, scallops, and lobster , garlic, whole grains, sunflower seeds, and Brazil nuts. Selenium is destroyed when foods are refined or processed.

Eating a variety of whole, unprocessed foods is the best way to get selenium in your diet. Selenium may be taken as part of a vitamin-mineral supplement, a nutritional antioxidant formula, or as a separate supplement.

Most supplements contain a form of selenium called selenomethionine. Some studies have used mcg per day for some conditions. But evidence suggests that taking that amount over a long period of time could increase your risk of developing diabetes.

Talk to your doctor before taking more than the recommended daily allowance. Because of the potential for side effects and interactions with medications, you should take dietary supplements only under the supervision of a knowledgeable health care provider.

Talk to your doctor before taking more than the recommended daily allowance of selenium. Although some studies have used doses of mcg, there is some evidence that this amount could increase your risk for diabetes. DO NOT exceed the upper tolerable limit of mcg.

Remember that you may also get some selenium in the foods you eat. If you are being treated with any of the following medications, you should not use selenium supplements without first talking to your health care provider.

Although selenium may help reduce side effects from drugs such as cisplatin, doxorubicin, and belomycin, it may also interfere with their cancer-fighting ability. If you are undergoing chemotherapy, talk to your oncologist before taking selenium or any other supplement.

Simvastatin Zocor and niacin have been shown to lower LDL bad cholesterol and raise HDL good cholesterol in people with heart disease. Taking certain antioxidants together, including selenium, along with these drugs may make them less effective.

In theory, selenium may also reduce the effectiveness of other statins, including atorvastatin Lipitor , fluvastatin Lescol , lovastatin Mevacor , and prevastatin Pravachol. Some researchers propose that women taking birth control pills may have higher levels of selenium in their blood.

If you take birth control pills, ask your doctor before taking extra selenium. These chemical compounds may lower levels of selenium in the body and cause symptoms of selenium deficiency. Algotar AM, Stratton MS, Ahmann FR, et al.

Phase 3 clinical trial investigating the effect of selenium supplementation in men at high-risk for prostate cancer. Beck MA, Nelson HK, Shi Q, Van Dael P, Schiffrin EJ, Blum S, Barclay D, Levander OA.