Nutritional approaches to the management of sarcopenia

Sarcopenia is defined as a decline in muscle mass and/or function, which is a consequence of ageing. The consequences of a declining muscle mass become serious if functionally important thresholds for physical independence are crossed, and this will occur more readily in the presence of disease. Although sarcopenia is of complex aetiology, contributory factors likely include habitual sedentarism and/or deficits in the responsiveness of muscle protein synthesis to physical activity and nutrition, as well as impaired muscular regenerative capacity. Altered inflammatory, immune and endocrine functions are also associated with sarcopenia, in addition to phenomena such as a reduced response to oxidative stress, metabolic acidosis and nutritional (e.g. vitamin D) deficiencies. Sarcopenia is associated with malnutrition, which may contribute to the poor muscle function observed in many older adults, particularly in frail patient groups. The problem is that as a result of anabolic resistance, simply increasing dietary protein 'chronically' in older age may not be effective. When exercise and nutritional interventions are combined in the form of resistance exercise training plus protein/essential amino acid supplementation, there is evidence of some benefit for older adults in terms of improved muscle function, but further research is needed in adults aged over 75 years. In addition, there are as yet relatively under-researched intervention strategies (timing and distribution of protein supplementation; novel nutriceuticals, vitamin D) bearing potential utility in improving responsiveness to physical activity and nutrition in old age.