Hydrolyzed casein and whey protein meals comparably stimulate net whole-body protein synthesis in COPD patients with nutritional depletion without an additional effect of leucine co-ingestion

Abstract

Background & Aims Muscle wasting commonly occurs in COPD, negatively affecting outcome. The aim was to examine the net whole-body protein synthesis response to two milk protein meals with comparable absorption rates (hydrolyzed casein (hCAS) vs. hydrolyzed whey (hWHEY)) and the effects of co-ingesting leucine. Methods Twelve COPD patients (GOLD stage II-IV) with nutritional depletion, were studied following intake of a 15g hCAS or hWHEY protein meal with or without leucine-co-ingestion, according to a double-blind randomized cross-over design. The isotopic tracers L-[ring-2H5]-Phenylalanine, L-[ring-2H2]-Tyrosine, L-[2H3]-3-Methylhistidine (given via continuous intravenous infusion), and L-[15N]-Phenylalanine (added to the protein meals) were used to measure endogenous whole-body protein breakdown (WbPB), whole-body protein synthesis (WbPS), net protein synthesis (NetPS), splanchnic extraction and myofibrillar protein breakdown (MPB). Analyses were done in arterialized-venous plasma by LC/MS/MS. Results WbPS was greater after intake of the hCAS protein meal (P<0.05) whereas the hWHEY protein meal reduced WbPB more (P<0.01). NetPS was stimulated comparably, with a protein conversion rate greater than 70%. Addition of leucine did not modify the insulin, WbPB, WbPS or MPB response. Conclusions Hydrolyzed casein and whey protein meals comparably and efficiently stimulate whole-body protein anabolism in COPD patients with nutritional depletion without an additional effect of leucine co-ingestion.

Quantity of dietary protein intake, but not pattern of intake, affects net protein balance primarily through differences in protein synthesis in older adults

“…3). This is consistent with recent studies demonstrating a linear relationship between protein intake and NB (12,13). Although AA oxidation increases correspondingly with increasing amounts of protein/AA intake (23), some portion of AAs is still being incorporated into protein.…”

“…For the calculations for whole body PB rate, contribution from exogenous meal and tracers infused was subtracted from total Ra. Appropriate skew correction was also made for 13 C-labeled tracers (35). Calculation of MPS was determined as the incorporation of the phenylalanine tracer over a 22-h time period (120 -1,440 min) using a precursor-product model (3).…”

Nutritional assessment and therapy in COPD: a European Respiratory Society statement

“…More research is required to exclude any impairment in protein synthesis signalling (i.e. its responsiveness to catabolic triggers), but assuming this is not the case [36], stimulating protein synthesis more proximally using nutritional intervention to counterbalance elevated proteolysis may contribute to muscle mass maintenance in the presence of increased protein turnover in cachectic patients. Nutritional intervention targeted at provision of sufficient amino acids to support protein synthesis signalling could evoke a compensatory response to increases in proteolysis cues, obviously presuming a positive energy balance [36].…”

A randomized clinical trial investigating the efficacy of targeted nutrition as adjunct to exercise training in COPD

“…Recent research has shifted towards the quality of dietary protein in terms of protein sources and supplementation of specific anabolic amino acids. Casein and whey, both high‐quality proteins because of their high essential amino acid (EAA) content, are shown to comparably and efficiently stimulate muscle protein synthesis 13. Leucine is one of the BCAAs known to increase insulin secretion and influence molecular regulation of muscle protein synthesis (via the mTOR pathway), thereby stimulating anabolism and muscle protein synthesis, provided sufficient supply of essential amino acids (EAA) to the muscles 6.…”