‘Every coin has two faces,’ ‘excess of everything is bad,’ and you might be hearing many other things like these. And, then this, peanut butter is not healthy, whey protein is not healthy, and many more.
Now, side effects of peanut butter! Well, everything said above is correct, but up to some extent.
You never have to trust everybody around you. Instead, use your own common sense, creativity and research thoroughly before you take any action.