Selenium is an important antioxidant trace mineral that works in conjunction with vitamin E. It forms part of the enzyme, glutathione peroxidase, which metabolizes hydroperoxides formed from polyunsaturated fatty acids. Selenium is also a part of enzymes that deiodinate thyroid hormones. It is studied for cancer prevention; preventing heart disease; skin protection; male fertility and prostate support; immune system support.
In China, where selenium intake averages 10 to 15 µg/day, selenium deficiency occurs in association with Keshan disease, an endemic viral cardiomyopathy affecting children and young women in that country. This cardiomyopathy can be prevented but not cured by selenite supplements of 50 µg/day. Patients receiving long-term TPN have developed selenium deficiency with muscle pain and tenderness that was responsive to a selenomethionine supplement. As part of the antioxidant glutathione peroxidase system, selenium plays a direct role in the body’s ability to protect cells from damage by free radicals.
In one large and well-controlled study, 200mcg of selenium (from high-selenium yeast) reduced the risk of several cancers: prostate (66%), colon (50%) and lung (40%) when compared to a group receiving a placebo.
Dietary Sources: The best dietary sources of selenium include nuts, unrefined grains, brown rice, wheat germ, and seafood.
Dosage: The recommended intake (DRI or Dietary Reference Intake) for selenium is 55-70mcg for adults (65-75mcg for pregnant and nursing women. In most clinical trials of selenium, doses are typically in the 100-200mcg/day range. In general, the organic (selenomethionine) form of selenium is absorbed somewhat better than the inorganic (selenite) form.
Safety: At the recommended dosage, 50-200mcg/day, selenium is considered safe. At high doses (> 900 µg/day), selenium produces a toxic syndrome consisting of dermatitis, loose hair, diseased nails, and peripheral neuropathy associated with plasma levels > 100 µg/dL (> 12.7 µmol/L).
Selenium research reveals the following:
1. Protects immune system from oxidative damage
2. Improves sperm motility and quality
3. Selenium supplementation leads to lower hospitalization rates for HIV patients
4. Reduces inflammation in autoimmune thyroiditis
5. Halts development of osteoarthritis
6. Helps prevent coronary heart disease
7. Protects against lipid and protein oxidation
8. Reduces severity of chronic heart failure
9. Protects against H pylori infection
10. Reduces atherogenic effect of high fat diet
11. Prevents recurrence of tumors
12. Those with systemic inflammatory response syndrome (SIRS) have low selenium levels
13. Those with chronic pancreatitis have low selenium levels
14. Is a powerful antioxidant
15. Is a free radical scavenger
16. Protects from UV skin damage
17. Protects against prostate cancer
18. Improves gait function in muscular dystrophy
19. Reduces mercury toxicity
20. May prevent LDL oxidation
21. May prevent renal failure in hemodialysis
22. May correct male fertility problems
23. Helps prevent reperfusion injury
24. Can reduce AIDS related mortality
25. Is a treatment for ulcerative colitis
26. Low selenium may lead to colon and rectal cancers
27. Reduces mortality from lung cancer
28. Reduces dental cavities
29. Low levels of selenium are associated with tiredness, anxiety and depression
30. Reduces incidence of thyroid, pituitary, liver and breast cancers
Selenium Citations (223)