Controlled trial of oligopeptide versus amino acid diet in treatment of active Crohn's disease.

Elemental diets are effective in inducing remission in active Crohn's disease, but how they exert this therapeutic effect is unclear. In a previous study a whole protein containing diet proved less effective than one in which food antigens were excluded, suggesting that exclusion of food antigens from the gut was a possible mechanism. This study was designed to test whether an oligopeptide diet of hydrolysed proteins was as effective as an amino acid based diet. These diets were equally antigen free but with different nitrogen sources. Forty four patients with active Crohn's disease were randomised in a controlled trial of amino acid versus oligopeptide diet. The feeds were given by nasogastric tube in equicaloric quantities and were the sole form of nutrition. Treatment was continued for four weeks although failure to improve by day 10 resulted in withdrawal. Quantitative leucocyte scintigraphy was used to investigate the effect of diet treatment on gut inflammation. Clinical and nutritional responses to treatment were also measured. Sixteen patients entered remission (including withdrawal of corticosteroids), six patients could not tolerate the nasogastric tube, and 22 patients failed to respond. The two diets were equally effective. Patients who responded had a rapid drop in clinical index of disease activity and a major reduction in the bowel uptake of leucocytes on scintigraphy. The oligopeptide and amino acid based enteral feeds were equally effective at inducing remission in active Crohn's disease. With both diets clinical improvement was accompanied by a reduction in intestinal inflammation.