Clinical Nutrition University: Nutrition in the prevention and management of irritable bowel syndrome, constipation and diverticulosis

Abstract

Many IBS patients believe that their symptoms are triggered by specific foods. However, demonstration of these food intolerances is difficult. True food allergy account for a minority of intolerances, whereas carbohydrate (i.e. lactose, fructose, sorbitol) malabsorption is easier to document. In general, patients with IBS can (and should) eat a balanced diet without restrictions, and (except for malabsorbed sugars) exclusion diets are not recommended. Increasing fibre intake has been recommended for years in IBS. However, the quality of the evidence supporting this recommendation is poor. Despite this, high-fibre diets or fibre supplements should not be totally withdrawn from the therapeutic armamentarium for IBS. Hydrophilic colloids prevent both excessive stool dehydration and excess liquidity, and may be equally effective for patients with predominant constipation or diarrhoea. Increasing fibre intake is useful in functional chronic constipation, but this may worsen symptoms in patients with colonic inertia and/or pelvic floor dyssynergia. Also, fibre intake may help some patients with uncomplicated diverticular disease (although the evidence is weak). There is a growing evidence for the effectiveness of probiotics in IBS, chronic constipation, and diverticular disease (depending on the strain used). Data on the usefulness of prebiotics in these situations are still very scarce.