Irritable Bowel Syndrome: Nutritional Considerations

Irritable bowel syndrome appears to have both nutrition- and stress-related etiologies. 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.¹⁰ Both diet 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. The rationale for treatment with increased fiber is the assumption that symptoms are caused by an increase in intraluminal pressure,¹¹ which is relieved by a bulking agent such as wheat bran. Several studies have revealed that adding bran fiber decreases bloating, constipation, and diarrhea in patients with irritable bowel syndrome. However, a placebo effect appears to account for some of these benefits, and a subpopulation of patients experience an exacerbation of symptoms (eg, bloating) with bran treatment.¹²

Other investigations have indicated that fiber types other than wheat bran (eg, partially hydrolyzed guar gum) are more effective for this purpose than wheat bran.¹¹ 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 irritable bowel syndrome. Among the foods that contain these compounds are milk, eggs, and wheat, the 3 foods that most frequently cause IBS exacerbations.^13,14 Elimination diets help roughly half of patients.¹⁵ An intervention in which beef, wheat, and dairy products were eliminated significantly reduced total symptom scores, an effect attributed to a dramatic decrease in gas (hydrogen and methane) production.¹⁶

Probiotic therapy. A number of studies have indicated differences in intestinal microbial populations between irritable bowel sufferers and controls, suggesting that antibiotic treatments may play a causative role.¹⁵ 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.^12,15

Peppermint oil. Enteric-coated peppermint oil capsules have been evaluated in controlled clinical trials and found helpful in reducing the symptoms of irritable bowel syndrome in more than half of patients overall, and in 75% of children.^17,18 Proposed mechanisms for its effects include calcium channel blocking on a local level, causing smooth muscle relaxation, and a direct antimicrobial effect against symptom-inducing bacterial overgrowth in the small intestine.¹⁹

Orders

See Basic Diet Orders chapter.

What to Tell the Family

Irritable bowel syndrome is a complex illness that is frequently exacerbated by stress and, possibly, by poor diet. Patients may benefit from taking medications, making diet changes that increase insoluble fiber (bran cereal, whole grain breads), and eliminating suspected offending foods. Stress reduction techniques and hypnotherapy may also be helpful.