<<Disclaimer: Verify this information before applying it to your situation.>> I don't have any experience with taking selenium, but I wonder if the original author has the correct doseage given. Do they really take 500 mg (milligrams) when selenium is sold in mcg (micrograms)? The recommended RDA that I found in "Life Expectations" is 200 mcg. Taking 500 milligrams would be two and a half thousand times above the RDA. Selenium is a heavy metal and too much of it can be dangerous. Ellen SF,CA