I've always believed that Mario ate the super mushrooms to increase muscle mass and he ate the fire flowers as well. But the super leaf he put on his head, similar to tanookies (Sp?) in legends. I read somewhere that a tanookie put a leaf on it's head to transform, and if someone else put the leaf on their head, they would transform into the last thing the tanookie transformed into with that leaf.
Also, didn't one of the recent rpgs mention that Mario ate the fire flowers? I can't remember very well....
