Q: Have there been any lab studies proving that Saw Palmetto works to prevent hair loss? — A.B., Yonkers, NY

A: There have been no verifiable clinical studies that show saw palmetto can stop hair loss or cause hair to re-grow. There have been some preliminary tests showing that saw palmetto may be able to inhibit 5-alpha-reductase, but its usefulness for androgenetic hair loss has not been documented in controlled studies.