Liver and biliary abnormalities are well-known complications of inflammatory bowel disease (IBD). It has been suggested that using total parenteral nutrition (TPN) may further impair liver function in these patients; this seems not to be so with total enteral nutrition (TEN). However, prospective trials comparing the incidence of liver function test (LFT) abnormalities with either TPN or TEN have not been carried out. Twenty-nine IBD inpatients with normal LFT, randomized to receive either TEN with a polymeric diet or isocaloric, isonitrogenous "all-in-one" TPN because of protein-energy malnutrition and/or severe disease, were included in the study. Sixteen patients (five with ulcerative colitis and 11 with Crohn's disease) received TEN, and 13 patients (eight ulcerative colitis and five Crohn's disease) were on TPN. All patients were on systemic steroids, and nine of them were on oral metronidazole. Both groups were homogeneous regarding age, sex, diagnosis, disease activity, nutritional status, daily nutrient supply, and days on artificial nutrition. Serum albumin levels significantly increased with TEN (32 +/- 1 to 38.2 +/- 1.6 g/liter, p less than 0.01), but not with TPN (32.1 +/- 2.2 to 33.9 +/- 1.4 g/liter, NS). Clinical improvement occurred in both groups of patients as shown by the change in the disease activity indexes. In all cases, measurements of serum alkaline phosphatase, serum bilirubin, aspartate aminotransferase, alanine aminotransferase, and gamma-glutamyltransferase were performed weekly. There were no significant differences in the initial LFT between both groups.(ABSTRACT TRUNCATED AT 250 WORDS)