You're not still eating peanut butter are you? Times have changed and what we know about food, nutrition and human physiology today has improved upon or even dispelled many beliefs we have about food in the past. Take peanut butter, for example. Sure, it's tasty, convenient, economical, popular with kids, but there is a darker side to peanuts and peanut butter that we need to look at.
If your from the southern US, you probably grew up on goober peas as they are called there. In the southern US, peanuts are boiled at length before they are consumed and are a snack sold everywhere. This preparation method – similar to the soaking of other legumes (beans) – releases the phytic acid within the nut as well as other enzyme inhibitors that prevent digestion.
Boiling the peanuts in this way makes them much easier to digest and their nutritional content available for assimilation by the body which is referred to as "bioavailability".
The problem is that at the consumer level peanuts are rarely boiled and both peanuts and peanut butters still contain these dangerous antinutrient compounds.
There is an even darker side to peanuts; mold. Peanuts may easily become moldy after being stored at farms, factories, processing centers adn store shelves with a toxic mold called Aspergillus flavus and A. parasiticus. This mold produces a highly toxic substance called aflatoxin that is a known carcinogen.
It gets even worse. Real peanut butter should only contains peanuts (Maybe a pinch of salt). However, most of that peanut butter you buy in the grocery may not even be peanut butter. Likely it's peanuts blended with fillers, emulsifiers, sugars, processed oils, artificial sweeteners - that's not peanut butter, that's an artificial spread with peanuts.
Special Warning For Pet Owners - if your peanut butter contains any additives it can likely be hazardous to your pet. If you must treat Fido with peanut butter, make sure it's plain pure organic peanut butter.