Oral glutamine accelerates healing of the small intestine and improves outcome after whole abdominal radiation.

The healing effects of glutamine given orally for 8 days as a single amino acid nutrient after treatment with whole abdominal radiation (10 Gy) were studied. Rats received isonitrogenous and isovolumic diets containing 3% glutamine or 3% glycine. Control rats were not irradiated but were given identical diets. In irradiated animals, survival was 100% in animals receiving glutamine compared with 45% in animals receiving glycine. Glutamine ingestion diminished bloody diarrhea and the incidence of bowel perforation. Arterial glutamine level was higher in animals receiving glutamine in the diet, as were gut glutamine extraction (35% +/- 8% vs 12% +/- 7%) and intestinal glutaminase activity. These metabolic improvements were associated with a marked increase in villous height, villous number, and the number of mitoses per crypt in rats receiving glutamine. Glutamine was not beneficial in control nonirradiated animals. The data demonstrated that provision of oral glutamine after abdominal radiation supported gut glutamine metabolism, improved mucosal morphometrics, and decreased the morbidity and mortality associated with this abdominal radiation model.