Peanut butter may cause constipation in those with irritable bowel syndrome, a digestive disorder with symptoms that include stomach pain, cramping and diarrhea. IBS with constipation is a form of irritable bowel syndrome characterized by bloating, abnormal bowel movements and hard or lumpy stools.
Fatty proteins, such as red meat and peanut butter, may cause digestion problems for people with IBS. Lean proteins, such as chicken and fish, are more easily digestible. Vegetables, fruits and beans, which are insoluble fibers, can help speed the passage of stools through the colon. Insoluble fibers should be introduced slowly, because they may cause gas and bloating.