Are you eating GOOD yogurt? With LIVE cultures? That should keep your flora good. You can add some megadophilus to that, I get the chewable, but you have to make sure your probiotics say "keep refrigerated" on them. If they are just on a store shelf, they aren't live and most likely not going to help much. That won't help your hair though, or your nails.

Oh...and I remember reading something about Biotin overdoses...so look that up as well.