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

SummaryBackgroundTo investigate the absorption and relative bioavailability of leucine administered orally as part of an enteral diet in well and malnourished animals.MethodsTwo 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.ResultsThe 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.ConclusionsIn 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.