Get the latest public health information from CDC. Have a question? This is a reader-friendly overview of Selenium. For more details, see our health professional fact sheet on Selenium. Selenium is a nutrient that the body needs to stay healthy. Selenium is important for reproduction, thyroid gland function, DNA production, and protecting the body from damage caused by free radicals and from infection. The amount of selenium that you need each day depends on your age.
Average daily recommended amounts are listed below in micrograms mcg. Selenium is found naturally in many foods. The amount of selenium in plant foods depends on the amount of selenium in the soil where they were grown.
The amount of selenium in animal products depends on the selenium content of the foods that the animals ate. You can get recommended amounts of selenium by eating a variety of foods, including the following:. Selenium is available in many multivitamin-mineral supplements and other dietary supplements.
It can be present in several different forms, including selenomethionine and sodium selenate. Most Americans get enough selenium from their diet because they eat food grown or raised in many different areas, including areas with soil that is rich in selenium.
Selenium deficiency is very rare in the United States and Canada. Selenium deficiency can cause Keshan disease a type of heart disease and male infertility. It might also cause Kashin-Beck disease, a type of arthritis that produces pain, swelling, and loss of motion in your joints. Scientists are studying selenium to understand how it affects health. Here are some examples of what this research has shown.
Studies suggest that people who consume lower amounts of selenium could have an increased risk of developing cancers of the colon and rectum, prostate, lung, bladder, skin, esophagus, and stomach. But whether selenium supplements reduce cancer risk is not clear.
More research is needed to understand the effects of selenium from food and dietary supplements on cancer risk. Antioxidants are compounds in foods that prevent cell damage caused by free radicals. Free radicals are normal byproducts of processes like metabolism that are formed in your body daily.
They often get a bad rap, but free radicals are essential for your health. They perform important functions, including protecting your body from disease. However, things like smoking, alcohol use, and stress can cause an excess of free radicals. This leads to oxidative stress, which damages healthy cells 1.
Antioxidants like selenium help reduce oxidative stress by keeping free radical numbers in check 7. They work by neutralizing excess free radicals and protecting cells from damage caused by oxidative stress.
In addition to decreasing oxidative stress, selenium may help lower the risk of certain cancers. A review of 69 studies that included over , people found that having a high blood level of selenium was associated with a lower risk of certain types of cancer, including breast, lung, colon, and prostate cancers 9. However, some research suggests that supplementing with selenium may reduce side effects in people undergoing radiation therapy. For example, one study found that oral selenium supplements improved overall quality of life and reduced radiation-induced diarrhea in women with cervical and uterine cancer A diet rich in selenium may help keep your heart healthy , as low selenium levels have been linked to an increased risk of heart disease.
For example, a review of 16 controlled studies including over , people with heart disease showed that taking selenium supplements decreased levels of the inflammatory marker C-reactive protein CRP. Additionally, it increased levels of glutathione peroxidase, a powerful antioxidant This indicates that selenium may help lower heart disease risk by reducing inflammation and oxidative stress in your body.
Oxidative stress and inflammation have been linked to atherosclerosis, or the buildup of plaque in arteries. Atherosclerosis can lead to dangerous health problems like strokes, heart attacks, and heart disease Incorporating selenium-rich foods into your diet is a great way to keep levels of oxidative stress and inflammation to a minimum.
Thus, finding ways to prevent this degenerative disease is imperative. One small study found that supplementing with one selenium-rich Brazil nut per day improved verbal fluency and other mental functions in patients with mild cognitive impairment Selenium is important for the proper functioning of your thyroid gland.
In fact, thyroid tissue contains a higher amount of selenium than any other organ in the human body This powerful mineral helps protect the thyroid against oxidative damage and plays an essential role in the production of thyroid hormones.
A healthy thyroid gland is important, as it regulates your metabolism and controls growth and development An observational study including over 6, people found that low serum levels of selenium were associated with an increased risk of autoimmune thyroiditis and hypothyroidism One review concluded that taking selenium supplements daily for three months resulted in lower thyroid antibodies. Your immune system keeps your body healthy by identifying and fighting off potential threats.
These foods include Brazil nuts, seafood, and meats. The amount of selenium in food depends on the concentration of the soil and water where it grew. People can also add the mineral to foods or consume it as a supplement. This article looks at the potential health benefits of selenium when a person consumes it from food or supplements, the recommended daily intake of selenium, and some possible health risks associated with selenium.
According to the ODS , selenoproteins may affect heart health by preventing the oxidative modification of lipids, or body fats. This may reduce inflammation and the buildup of platelets. However, there is no consistent clinical evidence to suggest that the mineral lowers the risk of cardiovascular disease, especially in healthy people who already get selenium from food. Some studies do indicate that people with less selenium in the blood are at higher risk of heart disease, but other studies refute this.
However, doctors do not yet recommend selenium for this purpose. Studies in the International Journal of Endocrinology and Nature Reviews Endocrinology suggest that having an optimal level of selenium in the body may help prevent thyroid disorders. This could especially be true for females. However, more research is underway to help inform how selenium supplements might support thyroid health.
However, this may depend on the type of selenium and the type of cancer a person has, according to a study. Other studies cited in a review indicate that selenium supplements may have little effect on cancer risk. Scientists have also suggested that selenium levels during pregnancy may be a factor in the development of childhood asthma. However, although selenium has links with many aspects of human health, there is not enough evidence to indicate that taking selenium supplements can prevent any of these conditions.
Selenium is most often found in whole grains and animal products such as fish and eggs. The amount of selenium in grains and grain-based foods depends on the soil content where they grew. The following foods are good sources of selenium:. The recommended DV for selenium is 55 mcg per day for most adults. During pregnancy, a person should consume 60 mcg, and while lactating, they should consume 70 mcg per day.
Selenium deficiency is rare worldwide, and it often takes years to develop. It usually only occurs in regions with severely low selenium content in the soil, such as several regions in China. However, according to the ODS , supplementation programs have mostly eradicated these deficiencies in the Chinese population. The upper limit for the optimal level of selenium in the body is mcg for adults.
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