- What other names is Selenium known by?
- What is Selenium?
- How does Selenium work?
- Are there safety concerns?
- Are there any interactions with medications?
- Dosing considerations for Selenium.
Most of the selenium in the body comes from the diet. The amount of selenium in food depends on where it is grown or raised. Crab, liver, fish, poultry, and wheat are generally good selenium sources. The amount of selenium in soils varies a lot around the world, which means that the foods grown in these soils also have differing selenium levels. In the U.S., the Eastern Coastal Plain and the Pacific Northwest have the lowest selenium levels. People in these regions naturally take in about 60 to 90 mcg of selenium per day from their diet. Although this amount of selenium is adequate, it is below the average daily intake in the U.S., which is 125 mcg.
Selenium is used for diseases of the heart and blood vessels, including stroke and "hardening of the arteries" (atherosclerosis). It is also used for preventing various cancers including cancer of the prostate, stomach, lung, and skin.
Some people use selenium for under-active thyroid, osteoarthritis, rheumatoid arthritis (RA), an eye disease called macular degeneration, hay fever, infertility, cataracts, gray hair, abnormal pap smears, chronic fatigue syndrome (CFS), mood disorders, arsenic poisoning, and preventing miscarriage.
Selenium is also used for preventing serious complications and death from critical illnesses such as head injury and burns. It is also used for preventing bird flu, treating HIV/AIDS, and reducing side effects from cancer chemotherapy.
Likely Effective for...
- Selenium deficiency. Taking selenium by mouth is effective for preventing selenium deficiency.
Possibly Effective for...
- Autoimmune thyroiditis (Hashimoto's thyroiditis). Research shows that taking 200 mcg of selenium daily along with thyroid hormone might decrease antibodies in the body that contribute to this condition. Selenium might also help improve mood and general feelings of well-being in people with this condition.
- Abnormal cholesterol levels. Some research shows that taking a 100-200 mcg of a specific selenium supplement (SelenoPrecise, Pharma Nord, Denmark) daily for 6 months can modestly reduce cholesterol levels. Many people in this study had low levels of selenium in their body before the start of the study. It is not clear if taking extra selenium would have any benefit on cholesterol levels in people with normal selenium levels in the body.
Possibly Ineffective for...
- Asthma. Research suggests that there is no link between selenium blood levels and asthma. Additionally, research suggests that taking 100 mcg of selenium daily for up to 24 weeks does not improve quality of life, lung function, asthma symptoms, or inhaler use in people with asthma.
- Eczema (atopic dermatitis). Research suggests that taking yeast that is enriched with 600 mcg of selenium daily for 12 weeks, alone or together with vitamin E, does not improve the severity of eczema.
- Heart disease. Taking 100 mcg of selenium in combination with beta-carotene, vitamin C, and vitamin E does not seem to prevent heart disease from becoming worse. Also, taking 200 mcg of selenium daily for almost 8 years does not reduce the risk of developing heart disease.
- Neurotoxicity caused by chemotherapy drugs. Early research suggests that taking vitamins C and E with selenium does not prevent neurotoxicity or hearing loss caused by the chemotherapy drug cisplatin.
- Critical illness (burns, head injury, trauma). Giving 500-1000 mcg of selenium intravenously (by IV) or 300 mg of selenium (ebselen) by mouth daily to critically ill people does not seem to reduce the risk of death or infection.
- Diabetes. Some research shows that people with low selenium levels have a higher chance of developing type 2 diabetes. However, other research shows that people who have high levels of selenium also have an increased risk of type 2 diabetes. Additionally, the most reliable research shows that people who take 200 mcg of selenium daily for about 7.7 years have an increased chance of developing type 2 diabetes.
- Hepatitis C. Research shows that taking 200 mcg of selenium along with vitamin C and vitamin E for 6 months does not improve liver function or virus levels in people with hepatitis C.
- Infertility. Research suggests that taking 100-200 mcg of selenium daily, alone or together with vitamin A, vitamin C, and vitamin E, for 3-4 months, does not improve sperm function in infertile men.
- Low birth weight. Daily selenium supplementation, 7 mcg/kg by mouth or 5 mcg/kg intravenously (by IV), does not appear to improve health in low birth weight infants.
- Lung cancer. Increasing selenium intake, either alone or along with vitamin E and beta-carotene, does not seem to lower the risk of getting lung cancer, except possibly in people who have lower than normal levels of selenium (selenium deficiency). Even in this group, the risk reduction is small.
- Prostate cancer. There has been a lot of interest in studying whether taking selenium lowers the chance of getting prostate cancer. The interest was triggered by the observation that prostate cancer seems to be less common in men with higher selenium levels in their bodies. To date, there have been several large, long-term scientific studies. The majority of this evidence suggests that selenium does not reduce the chance of getting prostate cancer.
- Red and irritated skin (psoriasis). Research suggests that taking yeast enriched with 600 mcg of selenium daily does not reduce the severity of psoriasis.
- Skin cancer. Taking 200 mcg of selenium does not seem to reduce the risk of getting a certain type of skin cancer called basal cell carcinoma. In fact, some scientific evidence suggests that taking extra selenium might actually increase the risk of getting another type of skin cancer called squamous cell carcinoma.
Insufficient Evidence to Rate Effectiveness for...
- Alcohol-related liver disease. Evidence shows that taking 200 mcg of selenium along with zinc and vitamin E daily can reduce the amount of time spent in the hospital and the risk of death in people with alcohol-related liver disease.
- Arsenic poisoning. Yeast enriched with selenium seems to decrease how much arsenic the body absorbs in Chinese people exposed to high levels of arsenic in the environment.
- Burns. Evidence suggests that taking 315-380 mcg of selenium along with copper and zinc daily can reduce the risk of pneumonia in people being treated in the hospital for burns. Other research suggests that this same combination might reduce the amount of time spent in the hospital but does not affect wound healing
- Cancer. Some research shows that taking 400 mcg of selenium daily for 2 years or 100 mcg of selenium along with zinc, vitamin C, vitamin E, and beta-carotene daily for 7.5 years does not reduce the risk of developing cancer. However, other research suggests taking selenium might reduce the risk of cancer-related death. Additionally, when subdivided by gender, some research shows that selenium might reduce the risk of cancer in men only, while selenium plus allitridum might decrease the risk of cancer in women only.
- Destruction of the bile ducts in the liver (cirrhosis). Taking selenium with vitamin A, vitamin C, methionine, and coenzyme Q10 for 12 weeks does not seem to improve fatigue or other symptoms in people with primary biliary cirrhosis.
- Colon and rectal cancer. Evidence is conflicting about the effect of selenium on colon and rectal cancer. A population study suggests that low selenium blood levels are not linked with an increased risk of developing colon and rectal cancer. Some research suggests that taking selenium, alone or with antioxidants, might reduce the risk of colon and rectal cancer or precancerous sores. However, other research suggests that selenium has no effect.
- Esophageal cancer. Taking selenium supplements does not seem to lower the risk of esophageal cancer.
- Stomach cancer. Taking selenium in combination with vitamin C and vitamin E for about 7 years does not seem to reduce the risk of developing precancerous stomach sores.
- HIV/AIDS. There is contradictory evidence about the effect of selenium supplements on HIV. Some evidence shows that taking selenium daily for up to 2 years can slow how quickly HIV spreads and can increase immune function. However, other early research shows that selenium has no effect.
- Low thyroid hormone levels (hypothyroidism). Some research shows that taking a selenium supplement might increase the conversion of thyroid hormones in older people. However, other research suggests that it has no benefit. Taking selenium can make hypothyroidism worse in people who are iodine deficient.
- Stroke. Some research suggests that administering selenium (ebselen) within 24 hours of a stroke improves recovery.
- Bone and joint disease (Kashin-Beck disease). Selenium does not seem to improve joint pain or movement in children with Kashin-Beck disease.
- Liver cancer. Early research in China suggests that taking selenium for 2-5 years can reduce the occurrence of liver cancer. It is unclear if taking selenium will reduce the risk of liver cancer in Western countries.
- Muscular dystrophy. Early research suggests that taking a water-soluble form of selenium daily for 6 months does not benefit people with muscular dystrophy.
- Arthritis (osteoarthritis). Low selenium levels seem to be linked with an increased risk of developing osteoarthritis. However, it is not known if selenium supplements can prevent osteoarthritis.
- Ovarian cancer. Research suggests that there is no link between selenium consumption in the diet and the risk for ovarian cancer.
- Overall risk of death. Some research suggests that taking 100 mcg of selenium along with zinc, vitamin C, vitamin E, and beta-carotene daily for 7.5 years might lower the risk of death from any cause in men, but not women. Other research suggests that selenium, taken alone or with other nutrients, does not reduce the risk of death.
- Pancreatitis. Evidence is conflicting about the effect of selenium on pancreatitis. Some research suggests that selenium has no benefit. However, other research suggests that taking a water-soluble form of selenium daily might reduce the risk of death caused by severe pancreatitis.
- Swelling in the arms and legs after surgery. Early evidence suggests that taking selenium supplements for 15 weeks might prevent bacterial skin infections in women with swelling in the arms and legs after breast cancer surgery.
- High blood pressure caused by pregnancy. Research suggests that taking 100 mcg of selenium liquid daily for 6-8 weeks during pregnancy can reduce the occurrence of high blood pressure.
- Rheumatoid arthritis (RA). Evidence on the effects of selenium on rheumatoid arthritis is inconsistent. Some research suggests that taking yeast enriched with 200 mcg of selenium does not improve RA. However, other research suggests that taking 200 mcg of selenium daily for 3 months reduces joint swelling, tenderness, and stiffness in people with RA.
- Sepsis. Some research suggests that administering selenium alone or with other antioxidants might reduce the risk of death caused by severe sepsis. However, other research suggests that administering selenium with L-arginine, omega-3 fatty acids, vitamin E, beta carotene, and zinc may increase the risk of death in people with sepsis.
- Inflammatory bowel disease (ulcerative colitis). Early research suggests that taking selenium with fish oil, natural sweeteners, gum arabic, vitamin E, and vitamin C does not benefit people with an inflammatory bowel disease called ulcerative colitis. However, taking this same combination does seem to reduce the need for medications.
- Macular degeneration (eye disease).
- Hay fever.
- Gray hair.
- Mood disorders.
- Chemotherapy side effects.
- Abnormal pap smears.
- Chronic fatigue syndrome (CFS).
- Bird flu.
- Preventing miscarriage.
- Other conditions.
Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, and Insufficient Evidence to Rate (detailed description of each of the ratings).
Next: How does Selenium work?
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