It's possible to take too much of any nutrient. With our Selenium supplement, it provides concentrated nutrition to fill in the gaps in your diet. One capsule, which is the daily suggested serving, offers 200 mcg of selenium. That is well within the safe upper limit (400 mcg/day) for adults. Regardless, we understand that everyone is different and that individual needs may vary. To better understand how much selenium you need and how it can affect you if you take more than necessary, we suggest checking in with your healthcare provider for additional tips and guidance.