Nutrition and ulcerative colitis.

The role of diet in the aetiology and pathogenesis of ulcerative colitis (UC) remains uncertain. Impaired utilization by colonocytes of butyrate, a product of bacterial fermentation of dietary carbohydrates escaping digestion, may be important. Sulphur-fermenting bacteria may be involved in this impaired utilization. Oxidative stress probably mediates tissue injury but is probably not of causative importance. Patients with UC are prone to malnutrition and its detrimental effects. However, there is no role for total parenteral nutrition and bowel rest as primary therapy for UC. The maintenance of adequate nutrition is very important, particularly in the peri-operative patient. In the absence of massive bleeding, perforation, toxic megacolon or obstruction, enteral rather than parenteral nutrition should be the mode of choice. Nutrients may be beneficial as adjuvant therapy. Butyrate enemas have improved patients with otherwise recalcitrant distal colitis in small studies. Non-cellulose fibre supplements are of benefit in rats with experimental colitis. Eicosapentaenoic acid in fish oil has a steroid-sparing effect which, although modest, is important, particularly in terms of reducing the risk of osteoporosis, but it seems to have no role in the patient with inactive disease. gamma-Linolenic acid and anti-oxidants also are showing promise. Nutrients may also modify the increased risk of colorectal carcinoma. Oxidative stress can damage tissue DNA but there are no data published at present on possible protection from oral anti-oxidants. Butyrate protects against experimental carcinogenesis in rats with experimental colitis. Folate supplementation is weakly associated with decreased incidence of cancer in UC patients when assessed retrospectively. Vigilance should be maintained for increased micronutrient requirements and supplements given as appropriate. Calcium and low-dose vitamin D should be given to patients on long-term steroids and folate to those on sulphasalazine.