If a person bites his nails - is it forbidden to swallow the nails?
Answer:
Although anything that is derived from something not kosher is itself not kosher, and it is forbidden to swallow human skin (see recent post on this matter), nails are not edible, and therefore the prohibition would not apply to eating them.
Yet, poskim do not permit healthy individuals to swallow non-kosher pills, and it would therefore be wrong to swallow nails, for which there is really no reason.