How can rancid peanut butter harm you?

Answer:

Rancid oils taste bad, and contain free radicals, some of which are potentially carcinogenic. The potential for harm is low, however; eating rancid peanut butter probably won't result in a doctor or hospital visit.

First answer by Curmudgeon1. Last edit by Curmudgeon1. Contributor trust: 18 [recommend contributor recommended]. Question popularity: 2 [recommend question].