I have encountered problems before on other sites where someone answers a medical question based on wikipedia or answers.com rather than having specific medical knowledge or training. Does this site have moderations powers enough to limit answering medical questions to medical professionals?
The short answer is no, we have no way of verifying medical qualifications or limiting answers to qualified health professionals.
As with other types of answers, if you believe an answer is incorrect or dangerous, downvote it and post a comment explaining (preferably with citation) why. We (moderators) generally do not evaluate the correctness of answers, but if it is clearly dangerous, flag it and a moderator will determine whether it's bad enough to delete.
This sort of question on various subjects has come up here and on other SE sites. Basically, users should be made to understand that any advice here is just suggestion made on anecdote, tradition, and hearsay, and is not medical advice; it's no more than asking your hiking buddies what they think. A good answer would, however, link to a reputable source to back up the contents.