Impact of nutritional status on the oral bioavailability of leucine administered to rats as part of a standard enteral diet

Abstract

Background: To investigate the absorption and relative bioavailability of leucine administered orally as part of an enteral diet in well and malnourished animals.

Methods: Two groups - RN (regular nutrition) and PCR (protein-calorie restricted) - were fed with different diets for 23-25 days. Rats from each group were assigned randomly to one of three treatments (water, T-Diet Plus Standard(®) (problem) or Isosource ST(®) (reference)) administered in single (N = 76) or multiple (N = 39) doses. Blood samples were assayed for leucine content. Area under the curve (AUC) was calculated by non-compartmental analysis. Log-transformed AUC(s) were statistically compared by analysis of variance, and 90% confidence intervals (CI 90%) of the ratio of the log-transformed AUC(s) between problem and reference diets, and between enteral diet and water were determined.

Results: The AUC (last) between the problem and reference diets was not statistically different. 90% CIs for single and multiple doses were 58.4-137.5% and 78-134.6% for RN and 76.7-172.2% and 72-167.2% for PCR, respectively. Leucine absorption was 12% higher among malnourished animals when multiple doses were administered, but the differences detected were not statistically different.

Conclusions: In spite of the different composition of proteins in the enteral diets tested, the absorption of leucine, even though slightly higher in the malnourished state, is similar in both of them.