I would never speculate about vitamins as I believe the mind is stronger than the body and Nadal is not the only one to have proven that but he takes winning ugly to a whole new level even Meds who is so quick to complain and lose his temper backed off completely in the USO from confronting Nadal all the way about using his hand up to stop him serving during break points.
He is the most exciting player by far yet the most abusive of gamesmanship where he uses dubious tactics that are not technically illegal to win, interrupt or gain serious advantages. There is no doubt that the greatest competitors of any sport have used gamesmanship but are quickly stamped out where in tennis it is probably the slowest to make changes until someone like Sir Murray speaks out.
BTW I think Nadals past team before Moya are all gentlemen who are down to earth and are not to blame for anything as anyone would do the same for their charge or friend.
Also neither is Nadal at fault for being a master of gamesmanship as he is doing what comes natural and part of the reason why his formulas work for him.
Macca playing Nadal today would be hitting officials by bending Rafas water bottles onto them with Messi like precision.