The effects of whey, pea, and collagen protein supplementation beyond the recommended dietary allowance on integrated myofibrillar protein synthetic rates in older males: a randomized controlled trial

Abstract

BackgroundSkeletal muscle mass is determined predominantly by feeding- and activity-induced fluctuations in muscle protein synthesis (MPS). Older individuals display a diminished MPS response to protein ingestion, referred to as age-related anabolic resistance, that contributes to the progression of age-related muscle loss – sarcopenia. ObjectiveWe aimed to determine the impact of consuming higher- versus lower-quality protein supplements above the recommended dietary allowance (RDA) on integrated MPS rates. We hypothesized that increasing total protein intake above the RDA, regardless of the source, would support higher integrated rates of myofibrillar protein synthesis. MethodsThirty-one healthy older males (72 ± 4 y) underwent a controlled diet with protein intake set at the RDA – control phase (CON; days 1-7). In a double-blind, randomized controlled fashion, participants were assigned to consume an additional 50g (2x25g) of Whey (WHEY, n=10), Pea (PEA, n=11), or collagen (COLL, n=10) protein each day (25 g at breakfast and lunch) during the supplemental phase (SUPP; days 8-15). Deuterated water ingestion and muscle biopsies assessed integrated MPS and acute anabolic signaling. Postprandial blood samples were collected to determine feeding-induced aminoacidemia. ResultsIntegrated-MPS was increased during SUPP with WHEY (1.59 ± 0.11 %/d, p<0.001) and PEA (1.59 ± 0.14 %/d, p<0.001) when compared with RDA (1.46 ± 0.09 %/d WHEY; 1.46 ± 0.10 %/d PEA); however, it remained unchanged with COLL. Supplemental protein was sufficient to overcome anabolic signaling deficits (mTORC1 and rpS6), corroborating the greater postprandial aminoacidemia. ConclusionsOur findings demonstrate that supplemental protein provided at breakfast and lunch over the current RDA enhanced anabolic signaling and integrated MPS in older males; however, the source of additional protein may be an important consideration in overcoming age-related anabolic resistance.Clinical Trial Registry number and website where it was obtained This trial (NCT04026607) was registered clinicaltrials.gov;