Effect of whey proteins, their oligopeptide hydrolysates and free amino acid mixtures on growth and nitrogen retention in fed and starved rats

Efficiency of enteral nitrogen support in surgical patients: small peptides v non-degraded proteins

In a prospective study, 12 intensive care patients, after abdominal surgery, received three alternate six-day courses of two enteral diets with identical nitrogen (0.3 g N/kg per day) and energy (60 kcal/kg per day) supply. The protein hydrolysate (PH) diet contained enzyme-hydrolysed casein and lactoserum (60% small peptides), while the non-degraded protein (NDP) diet contained a nitrogen source of similar amino acid composition, but in the form of non-degraded proteins. The patients were randomised to receive either PH-NDP-PH or NDP-PH-NDP. Parameters reflecting protein metabolism were assessed in the plasma, urine, and stomal effluent on days 1, 6, 12, and 18, three hours after stopping the nutrition (t0), and one hour after restarting it (t1). Comparisons of t1 and t0 values showed that 13 amino acids (including the eight essential amino acids) increased significantly with the protein hydrolysate diet, but only two increased with the non-degraded protein diet. Similarly, with protein hydrolysate, insulin-aemia at t1 was significantly higher than at t0 and correlated with plasma leucine, phenylalanine, alanine, and lysine concentrations. In addition, significant improvements in plasma albumin, transferrin, and retinol binding protein concentrations were seen with protein hydrolysate, together with a significant decrease in the plasma phenylalanine/tyrosine ratio and urinary 3-methylhistidine excretion. We conclude that in patients in intensive care after abdominal surgery enteral support containing small peptides is more effective than an equivalent diet containing whole proteins in restoring plasma amino acid and protein levels.

A reappraisal of the peptide-based enteral formulas: clinical applications

The development of peptide-based enteral formulas is a significant milestone in the advancement of nutritional care of the nutritionally compromised patient. Although previously limited to specific gastrointestinal mucosal diseases, the use of peptide-based formulas has been extremely useful in the critically ill patient with impaired gastrointestinal absorption associated with hypoalbuminemia resulting from hypermetabolic states. Based on previous animal studies, several investigators have noted improved nitrogen absorption, greater nitrogen utilization, higher branched chain amino acid levels, and increased insulin secretion with the use of peptide-based formulas compared with intact protein or free amino acid diets. Recent studies have indicated an improved gastrointestinal tolerance with peptide-based diets, with the rate of absorption and the degree of tolerance dependent on the presence of small molecular weight peptides. In addition, we have found that the critically ill patient suffering from severe hypoalbuminemia frequently develops a protein-losing enteropathy, which can be attenuated by the use of a peptide-based formula. Thus, peptide-based formula may attenuate albumin turnover in the intestine and thus be efficacious in patients with a protein-losing enteropathy from a variety of etiologies (table 2). We therefore recommend that enteral support with a peptide-based diet is safe and extremely useful in the catabolic, critically ill patient or in patients with significant gastrointestinal malabsorption associated with a protein-losing enteropathy. Tolerance of these formulas is dependent on the catabolic state of the patient, with more catabolic patients needing higher concentrations of nitrogen in the form of peptides and/or supplemental parenteral branched chain amino acids.(ABSTRACT TRUNCATED AT 400 WORDS)