Despite what you might have heard from your dietitian or the media, humans don’t need fiber to maintain a healthy digestive tract and normal bowel habits. I strongly recommend not using fiber supplements (such as Metamucil) or maintaining a high-fiber diet because both can worsen IBS symptoms. As far as my experience with fiber supplements is concerned, I can tell you that inulin worsened my symptoms while psyllium husk and acacia fiber had no impact whatsoever on my IBS symptoms.