Irritable Bowel Syndrome: Nutritional Considerations

IBS is a complex illness that is frequently exacerbated by stress and, possibly, by poor diet. As with some other intestinal diseases, it may be more common in individuals consuming Western diets than in persons consuming the high–fiber, low–fat diets that are traditional in developing societies. Both dietary and psychological interventions have resulted in symptomatic improvements, and it is likely that patients will benefit most from a combination of medical, nutritional, and behavioral approaches. The following measures may be helpful:

• Increased insoluble fiber (e.g., bran cereal, whole grain breads): Several studies have revealed that increasing bran fiber intake decreases bloating, constipation, and diarrhea in patients with IBS. However, a placebo effect appears to account for some of those benefits, and some patients experience worsening symptoms (e.g., bloating) with bran fiber treatment.
  
  Other investigations have indicated that fiber types other than wheat bran (e.g., partially hydrolyzed guar gum) are more effective. Additional controlled clinical trials are needed in which different types of fiber are compared for their effectiveness. 
  
• Elimination diets for patients with adverse food reactions: Salicylates, amines, and glutamates in foods are suspected of causing symptoms of IBS. Among the foods that contain these compounds are milk, eggs, and wheat, the three foods that most frequently cause IBS flare–ups. Diets that eliminate these foods have been shown to help roughly half of patients.
  
  Further, an intervention in which beef, wheat, and dairy products were eliminated significantly reduced symptoms, which may be due to a dramatic decrease in intestinal gas production. Many cases of irritable bowel symptoms are probably due to lactose intolerance. For this reason, eliminating milk and dairy is an especially useful intervention. 
• Probiotic therapy: A number of studies have indicated differences in intestinal microbe populations between irritable bowel sufferers and control subjects, suggesting that antibiotic treatments may play a causative role. Repopulating the intestinal tract with “friendly” bacteria may be of benefit. Most studies have suggested a benefit from probiotic treatment with Lactobacillus plantarum, Bifidobacterium breve, Streptococcus faecium, and combinations of these with other organisms.
• Peppermint oil: Enteric–coated peppermint oil capsules have been evaluated in controlled clinical trials and found helpful in reducing the symptoms of IBS in more than half of patients overall, and in 75 percent of children.