As for Brewers yeast--I have read that it was highly recommended during the late 60's, 70's and 80's. And that many people became allergic to it from over use since it was readily used as a food additive. I understand that it became a standard part if most supplements during that time. Now you'll notice that most vitamins etc. are labled (contains no yeast). I would avoid this at all costs, just as we are advised to avoid other yeasts and yeast products.