Hopefully you don't mean for him to get regular peanut butter. Make sure you get the all NATURAL kind. Regular peanut butter is something like 40% peanuts and the rest hydrogenated oils = bad fat. Regular peanut butter is god damn awful for you.

It will take a while to get used to natural peanut butter because the oil and solids seperate so you have to stir it unless you keep it refridgerated. Still, go light on it and only use it for a snack every now and then unless you are trying to bulk up, cause it is loaded with calories. I can't even touch regular peanut butter anymore, its tastes awful to me compared to the real thing.