Targeting the Gut Microbiota to Improve Dietary Protein Efficacy to Mitigate Sarcopenia.

Elena De Marco Castro,Caoileann H Murphy,Helen M Roche

doi:10.3389/fnut.2021.656730

Elena De Marco Castro, Caoileann H Murphy + Show 1 more

Open Access

https://doi.org/10.3389/fnut.2021.656730

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Abstract

Sarcopenia is characterised by the presence of diminished skeletal muscle mass and strength. It is relatively common in older adults as ageing is associated with anabolic resistance (a blunted muscle protein synthesis response to dietary protein consumption and resistance exercise). Therefore, interventions to counteract anabolic resistance may benefit sarcopenia prevention and are of utmost importance in the present ageing population. There is growing speculation that the gut microbiota may contribute to sarcopenia, as ageing is also associated with [1) dysbiosis, whereby the gut microbiota becomes less diverse, lacking in healthy butyrate-producing microorganisms and higher in pathogenic bacteria, and [2) loss of epithelial tight junction integrity in the lining of the gut, leading to increased gut permeability and higher metabolic endotoxemia. Animal data suggest that both elements may impact muscle physiology, but human data corroborating the causality of the association between gut microbiota and muscle mass and strength are lacking. Mechanisms wherein the gut microbiota may alter anabolic resistance include an attenuation of gut-derived low-grade inflammation and/or the increased digestibility of protein-containing foods and consequent higher aminoacidemia, both in favour of muscle protein synthesis. This review focuses on the putative links between the gut microbiota and skeletal muscle in the context of sarcopenia. We also address the issue of plant protein digestibility because plant proteins are increasingly important from an environmental sustainability perspective, yet they are less efficient at stimulating muscle protein synthesis than animal proteins.

Highlights

Sarcopenia refers to the adverse muscle changes that accrue overtime, resulting in the loss of skeletal muscle quantity and quality [1]
Ageing is often associated with a reduction in muscle mass and function together with a reduction in abundance, resilience, and diversity of the gut microbiota [31, 50, 61, 62]
While emerging evidence supports a putative link between the gut and the muscle that could be a potential target for the prevention and treatment of sarcopenia, a causal relationship between the gut microbiota and muscle protein synthesis has not yet been established in humans, albeit evidence from murine models is strong [29]

Summary

INTRODUCTION

Sarcopenia refers to the adverse muscle changes that accrue overtime, resulting in the loss of skeletal muscle quantity and quality [1]. Resistance exercise, regulation of other nutrient sensors that modulate MPS aside from AA, and/or even greater amounts of protein supplementation/intake than those offered in this study may be essential tools to fight sarcopenia in healthy older adults. Gut microbiota transplantation from pathogen-free mice into germ-free mice restored skeletal muscle mass, reduced muscle atrophy markers, improved oxidative metabolic capacity of the muscle, and elevated Rapsyn and Lrp expression, both of which are essential for neuromuscular junction maintenance [29, 42]. Claesson et al [31] carried out a cross-sectional study in 178 individuals aged 78 ± 8 years old and living in three different settings (community dwelling, short-term rehabilitation hospital care, and long-term residential care) They showed that the gut microbiota of the participant was clustered by living setting and was related to dietary intake [31]. Muscle strength, but not lean mass or endurance, was significantly higher in mice colonised with microbiota from high- vs. low-functioning older adults [64]

PROBIOTIC AND THE GUT MICROBIOTA

AND PROTEIN DIGESTIBILITY

CONCLUSION AND FUTURE PERSPECTIVES