Age-related sarcopenia and the gut microbiome: mechanistic insights into the gut-muscle axis and potential microbiome based therapeutic interventions

Ageing is associated with a loss of skeletal muscle mass, strength and function, termed sarcopenia. The presence of sarcopenia is known to be problematic leading to an increased risk of falls, fractures and mortality. Age-related changes in the gut microbiome, characterized by reduced diversity and altered metabolite production, may compromise intestinal barrier function, leading to increased permeability. These age-associated changes in the gut microbiome led to changes in circulating microbial metabolites and toxins, such as a decrease in short-chain fatty acids, an increase in lipopolysaccharides and an imbalance in bile acid production. Together these alterations may contribute to the development of sarcopenia through impairments in muscle protein turnover. Currently, lifestyle-based approaches e.g., exercise and diet, alongside the use of pre-, pro- and post-biotics have been proposed as strategies to target the gut-muscle axis and combat the risk of sarcopenia in the expanding ageing population. However, little evidence is available to support their use within clinical settings. Several new strategies including the nutraceutical Urolithin A and faecal microbiome transplants (FMT) have been suggested to treat age-related sarcopenia. This review provides insight into the potential interactions of the gut microbiome and skeletal muscle with ageing and sarcopenia development, alongside potential new and existing countermeasures. • Advancing age is accompanied by a shift in gut microbiota composition, loss of functional microbial metabolites (including SCFAs) and an increased intestinal barrier permeability. • A common clinical complication associated with ageing is an accelerated loss of skeletal muscle mass, strength and physical function termed sarcopenia. • Age associated alterations in the gut microbiome homeostasis is a potential driver of sarcopenia in older adults. Alterations such as a decrease in SCFA that play a protective role against muscle atrophy by influencing muscle growth and proliferation. • Management of sarcopenia through modifications in the gut-microbiome (via exercise, nutritional supplementation and faecal microbiota transplantation) presents a novel therapeutic target.