How much selenium should you take?
The recommended dietary allowance (RDA) includes the total amount of selenium you should get from foods and from any supplements you take. Most people can get their RDA of selenium from food.
In studies to determine if selenium could aid in prostate cancer prevention, men took 200 micrograms daily.
The safe upper limit for selenium is 400 micrograms a day in adults. Anything above that is considered an overdose.