PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0-2 Life expectancy: Not specified Hematopoietic: Not specified Hepatic: Not specified Renal: Creatinine less than 2 times upper limit of normal Other: No known allergy to glutamine No history of inflammatory bowel disease No other medical condition that may interfere with treatment Not pregnant or nursing Adequate contraception is required of all fertile patients