Efficacy of two elemental diets: a pair feeding study.

The efficacy and side effects of two elemental diets were studied. Twenty young Sprague-Dawley rats were fed one of three different diets. Group I (n = 7) was fed Vivonex-HN (VIV) ad lib; group II (n = 7) was given Criticare-HN (CRI), pair-fed to group I (the two elemental diets were given in glass bottles); group III was fed regular rat chow and served as control (CON). Body weight (WT), food intake, and nitrogen balance (NB) were measured daily. After 21 days, change in body weight was similar in the three groups (VIV = 64.9 +/- 3.2%; CRI = 59.6 +/- 3.3%; CON = 63.9 +/- 4.8%). Cumulative nitrogen balance was also similar in the two groups fed elemental diets (VIV = 4788 +/- 277 mg N; CRI = 4690 +/- 118 mg N), but in both these groups it was less than the control group fed chow (8060 +/- 85 mg N). Blood urea nitrogen (BUN) on the last day was higher in the VIV group (12.9 +/- 1.22 mg/dl) than in the CRI group (9.43 +/- 0.43 mg/dl), but in both study groups it was lower than in the CON group (17.2 +/- 1.08 mg/dl), although nitrogen intake was higher in the control (ad lib) group. SGPT was similar in the two elemental diets but higher than in CON. Liver weights were higher in the CRI group, probably abnormally so and likely due to increased fat content. Both diets had similar efficacy in nutritional support.