Vitamin B3 that is found in peanut butter is a supplement that may help people with osteoarthritis, according to the Arthritis Research Institute of America. [See: Are Vitamins and Supplements Worth Taking?] Also, research suggests that diets rich potassium, of which peanut butter has a lot, may help prevent bone loss. Peanut butter has resveratrol, a natural antibiotic and antioxidant, which makes it a good toothache medicine.