Cinnamon's active compound is cinnamaldehyde, and it is a serious antimicrobial — effective enough against fungi and bacteria that it is studied as a food preservative. That is the basis for its use here against athlete's foot and plantar warts.
Its second action is warming. Cinnamon dilates surface blood vessels and produces real heat in the skin, which is why the book lists it for cold feet, for arthritis, and for the stiffness that comes with poor circulation.
It appears here more than almost any other kitchen ingredient, and that reflects a genuine breadth. It is also, like garlic and oregano, strong enough to burn if you are careless.
