I know I grew up being told that when an animals hair is course and dry they have parasites, so it would make sense to me that the same would happen with humans probably, hence if parasite infection is cleared, hair should begin improving, though maybe only the new hair as it grows out since damaged hair can't always be repaired.
Anyway, anxious to hear the response on this one as I had never thought of it before and I'm ALL ABOUT anything that improves skin, hair, nails ect.