What is the potential importance of taking selenium?

Dietary intake of selenium appears to be adequate in most people. This is according to recent studies in the U.S. based on the Recommended Dietary Allowance of 70 mcg per day of selenium. However, a double-blind study found that people given a supplement of 200 mcg of yeast-based selenium per day for 4.5 years had a 50% drop in the cancer death rate over seven years compared with the placebo group. Higher amounts of selenium than are available in the diet may be necessary for this protective effect. The upper end of safe long-term selenium intake has been estimated to be 350 to 400 mcg per day.