There are a lot of reputable suppliers of various nutrition supplements. You can go on Amazon and search for products shipped and sold by Amazon, and as long as

There are a lot of reputable suppliers of various nutrition supplements. You can go on Amazon and search for products shipped and sold by Amazon, and as long as you pick a brand that is recognized then you should be good. https://www.amazon.com/s?k=selenium&rh=p_6%3AATVPDKIKX0DER&s=review-rank https://www.amazon.com/s?k=selenium&rh=p_6%3AATVPDKIKX0DER&s... Note that Selenium has been found to have toxicity at higher amounts. 200 mcg should be good once per day, but you should be aware of any signs of toxicity or interactions.