And to complicate matters even more, many vitamin and mineral supplements are made with synthetic forms of vitamins that aren't readily absorbed, or could actually be detrimental. (truthaboutabs.com)
There is also a combination of both which you can find in synthetic form. (drchristianson.com)
As such, people should beware of buying any yeast supplement that is fortified with synthetic forms of this vitamin. (thehealthyhomeeconomist.com)