component of the enzyme glutathione peroxidase, which serves to act as a potent antioxidant. Being the most famous trace mineral with anti – cancer activity, selenium has multiple functions in the body.Functions of Selenium:
1) Acts as an antioxidant by being a part of glutathione peroxidase particularly when combined with vitamin E.
2) Has anti – cancer activity especially against prostate and colon cancers.
3) Has a key role in the production of thyroid hormones.
4) Improves the production and motility of sperms.
5) Enhances immune system by stimulating the production of antibodies in response to vaccines.
6) May help protein synthesis, growth and development.
7) May have a cardioprotective effect.
8) Selenium can ameliorate or even reverse mercury toxicity in animal models.
Food Sources and Absorption:
Foods high in selenium are brewer`s yeast, Brazilian nuts, wheat germ, liver, fish, seafood, cereals, and whole grain. Approximately 60% of dietary selenium is absorbed from the small intestine. Amino acids enhance the absorption of selenium to 85%.
Selenium deficiency may manifest as heart diseases (such as cardiomyopathy and heart failure), degeneration of skeletal muscles characterized by decreased muscle bulk and strength, and increased rates of cancers.
Athletic Benefits of Selenium:
- May speed up the healing process in sports injuries.
- May aid recover from overtraining syndrome.
- When combined with vitamins E and C, it may enhance recovery after intense strength training.
- Protects muscles against oxidative damage.
- May accelerate healing process in Osgood – Schlatter disease.
Non – Athletic Benefits of Selenium
Selenium may be beneficial in the following conditions:
- Male infertility.
- Asthma.
- Atherosclerosis.
- Hypothyroidism.
- Prostate cancer.
- Colon cancer.
- Keshan`s cardiomyopathy
- Compromised immune system.
- Liver cirrhosis.
- Diabetic retinopathy.
- Abnormal Pap smear.
- Dermatitis herpetiformis.
- Age – related macular degeneration.
- Periodontal disease.
- Acne.
- Cataract.
- Depression.
- Rheumatoid arthritis (RA).
Dosage and Side Effects:
The RDA for selenium for adult is 55 mcg. However, a dose of 100 – 200 mcg a day is considered safe. The performance daily intake (PDI) for athletes and physically active adults is 200 – 300 mcg.
Even though the tolerable upper limit for selenium for adult is 400 mcg a day, chronic ingestion of large amounts of selenium (more than 800 mcg a day) leads to selenium toxicity characterized by nausea, vomiting, hair loss, brittle nails, garlic breath odor, skin rash, irritability, muscle weakness, lassitude, and tooth decay. Occupationally, chronic ingestion of high doses of selenium may increase risk of lung inflammation and cancer, liver damage, and nasal cancer.
Selenium is available in the forms of tablets and capsules as 50 mcg, 100 mcg, and 200 mcg.
Interactions:
The potential interactions of selenium are as follows:
- Blood thinners (warfarin, clopidogrel, aspirin, and heparin): selenium may increase their effectiveness and risk of bleeding.
- Corticosteroids: they may decrease blood levels of selenium.
- Valproic acid: it may decrease blood levels of selenium.
- Clozapine: it may decrease blood levels of selenium.
- Cholesterol – lowering medications (such as simvastatin, atorvastatin, lovastatin and vitamin B3): selenium may reduce their effectiveness.
