SELENIUM Overview Information
Selenium is a mineral. It is taken into the body in water and foods. People use it for medicine.
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.
How does it work?
Selenium is important for making many body processes work correctly. It seems to increase the action of antioxidants.
Likely Effective for:
- Preventing lower than normal levels of selenium (selenium deficiency).
Possibly Effective for:
- Autoimmune thyroiditis (Hashimoto's thyroiditis). Taking selenium 200 mcg 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 thyroiditis.
- High cholesterol. Some research shows that taking a specific selenium supplement (SelenoPrecise, Pharma Nord, Denmark) 100-200 mcg 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:
- Preventing cancer. Clinical research shows that taking a combination of selenium 100 mcg along with zinc 20 mg, vitamin C 120 mg, vitamin E 30 mg, and beta-carotene 6 mg/day once daily for 7.5 years does not lower the overall chance of developing cancer of any type.
- Skin cancer. Taking 200 mcg of selenium does not seem to reduce the risk of getting a particular 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.
- Lung cancer. Increasing selenium intake doesn’t seem to lower the risk of getting lung cancer, except in people who have lower than normal levels of selenium (selenium deficiency). Even in this group, the risk reduction is small.
- Heart disease. Some research shows that people with heart disease who take selenium 100 mcg daily in combination with beta-carotene, vitamin C, and vitamin E do not seem to have a lower chance of having heart disease worsening or heart attacks.
- Diabetes. Some research has shown that people with low selenium levels in the body have a higher chance of getting type 2 diabetes. But other research shows that people who have high amounts of selenium in the body also have increased chance of getting type 2 diabetes. Additionally, more reliable research shows that people who take a selenium supplement 200 mcg daily for an average of 7.7 years actually have a significantly increased chance of getting type 2 diabetes.
- Rheumatoid arthritis (RA).
- Critical illness (burns, head injury, etc).
Likely Ineffective for:
- 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.
- HIV/AIDS. There is contradictory evidence about the effect of selenium supplements on HIV.
- Arthritis (osteoarthritis). Low selenium levels seem to be linked with an increased risk of developing osteoarthritis. But it’s not known whether selenium supplements can prevent osteoarthritis.
- Colorectal cancer. Evidence is conflicting about the effect of selenium on colorectal cancer.
- Esophageal cancer. Taking selenium supplements does not seem to significantly decrease the risk of esophageal cancer.
- Stomach cancer. Taking selenium in combination with vitamin C and vitamin E long-term (for about 7 years) does not seem to reduce the risk of developing precancerous stomach sores.
- Macular degeneration (eye disease).
- Hay fever.
- Gray hair.
- Mood disorders.
- Chemotherapy side effects.
- Swelling after surgery.
- Abnormal pap smears.
- Chronic fatigue syndrome (CFS).
- Bird flu.
- Preventing miscarriage.
- Overall cancer risk.
- Other conditions.
SELENIUM Side Effects & Safety
Selenium is LIKELY SAFE for most people when taken by mouth in doses less than 400 mcg per day, short-term.
Higher doses are POSSIBLY UNSAFE. They can cause significant side effects including nausea, vomiting, nail changes, loss of energy, and irritability. Poisoning from long-term use is similar to arsenic poisoning, with symptoms including hair loss, white horizontal streaking on fingernails, nail inflammation, fatigue, irritability, nausea, vomiting, garlic breath odor, and a metallic taste.
Selenium can also cause muscle tenderness, tremor, lightheadedness, facial flushing, blood clotting problems, liver and kidney problems, and other side effects.
There is concern that taking selenium for a long time might not be safe. Long-term consumption of selenium supplements appears to increase the chance of getting type 2 diabetes. It also seems to increase the risk of skin cancer recurrence. There is also some concern that having too much selenium in the body might increase the risk of overall death as well as death from cancer.
Special Precautions & Warnings:Pregnancy and breast-feeding: Selenium use is POSSIBLY SAFE during pregnancy and breast-feeding when used short-term in amounts that are not larger than 400 mcg per day.
Fertility problems in men: Selenium might decrease the ability of sperm to move, which could reduce fertility. If you are trying to father a child, don’t take selenium supplements.
Prostate cancer: There is concern that taking large amounts of a multivitamin plus a separate selenium supplement might increase the chance of developing prostate cancer and dying from prostate cancer.
A history of skin cancer: Long-term use of selenium supplements might slightly increase the risk of skin cancer recurrence, but this is controversial. Until more is known about the possible increase in skin cancer risk, avoid long-term use of selenium supplements if you have ever had skin cancer.
Under-active thyroid (hypothyroidism): Taking selenium can worsen hypothyroidism especially in people with iodine deficiency. In this case, you should take iodine along with selenium. Check with your healthcare provider.
Surgery: Selenium might increase the risk of bleeding during and after surgery. Stop taking selenium at least 2 weeks before a scheduled surgery.
Moderate Interaction Be cautious with this combination
- Medications that slow blood clotting (Anticoagulant / Antiplatelet drugs) interacts with SELENIUM
Selenium might slow blood clotting. Taking selenium along with medications that also slow clotting might increase the chances of bruising and bleeding.
Some medications that slow blood clotting include aspirin, clopidogrel (Plavix), dalteparin (Fragmin), enoxaparin (Lovenox), heparin, ticlopidine (Ticlid), warfarin (Coumadin), and others.
- Medications used for lowering cholesterol (Statins) interacts with SELENIUM
Taking selenium, beta-carotene, vitamin C, and vitamin E together might decrease the effectiveness of some medications used for lowering cholesterol. It is not known if selenium alone decreases the effectiveness of some medications used for lowering cholesterol.
Some medications used for lowering cholesterol include atorvastatin (Lipitor), fluvastatin (Lescol), lovastatin (Mevacor), and pravastatin (Pravachol).
- Niacin interacts with SELENIUM
Taking selenium along with vitamin E, vitamin C, and beta-carotene might decrease some of the beneficial effects of niacin. Niacin can increase the good cholesterol. Taking selenium along with these other vitamins might decrease the how well niacin works for increasing good cholesterol.
- Sedative medications (Barbiturates) interacts with SELENIUM
The body breaks down medications to get rid f them. Selenium might slow how fast the body breaks down sedative medications (Barbiturates). Taking selenium with these medications might increase the effects and side effects of these medications.
- Warfarin (Coumadin) interacts with SELENIUM
Selenium might thin the blood. Selenium might also increase the effects of warfarin in the body. Taking selenium along with warfarin might increase the chances of bruising and bleeding.
Minor Interaction Be watchful with this combination
- Birth control pills (Contraceptive drugs) interacts with SELENIUM
Some research shows that women who take birth control pills might have increased blood levels of selenium. But other research shows no change in selenium levels in women who take birth control pills. There isn't enough information to know if there is an important interaction between birth control pills and selenium.
Some birth control pills include ethinyl estradiol and levonorgestrel (Triphasil), ethinyl estradiol and norethindrone (Ortho-Novum 1/35, Ortho-Novum 7/7/7), and others.
- Gold salts interacts with SELENIUM
Gold salts bind to selenium and decrease selenium in parts of the body. This might decrease the normal activity of selenium, possibly resulting in symptoms of selenium deficiency.
Gold salts include aurothioglucose (Solganal), gold sodium thiomalate (Aurolate), and auranofin (Ridaura).
The following doses have been studied in scientific research:
- Autoimmune thyroiditis (Hashimoto's thyroiditis): 200 mcg daily.
- High cholesterol: 100-200 mcg daily of a specific selenium product (SelenoPrecise, Pharma Nord, Denmark).
- Children 1-3 years, 20 mcg; children 4-8 years, 30 mcg; children 9-13 years, 40 mcg;
- People over 13 years, 55 mcg;
- Pregnant women, 60 mcg; and lactating women, 70 mcg. Due to the demands of the fetus on the mother, the dietary need for selenium increases during pregnancy.
- The RDA for infants has not been determined. For infants up to 6 months old, 2.1 mcg/kg is adequate intake (AI). The AI for infants 7-12 months is 2.2 mcg/kg per day.
- Adults, 400 mcg per day for adults and adolescents 14 years and older.
- The tolerable upper intake level (UL) for infants up to age 6 months is 45 mcg per day;
- Infants 7 to 12 months, 60 mcg per day;
- Children 1 to 3 years, 90 mcg per day;
- Children 4 to 8 years, 150 mcg per day;
- Children 9 to 13 years, 280 mcg per day.