Dietary protein considerations to support active aging

Abstract

Given our rapidly aging world-wide population, the loss of skeletal muscle mass with healthy aging (sarcopenia) represents an important societal and public health concern. Maintaining or adopting an active lifestyle alleviates age-related muscle loss to a certain extent. Over time, even small losses of muscle tissue can hinder the ability to maintain an active lifestyle and, as such, contribute to the development of frailty and metabolic disease. Considerable research focus has addressed the application of dietary protein supplementation to support exercise-induced gains in muscle mass in younger individuals. In contrast, the role of dietary protein in supporting the maintenance (or gain) of skeletal muscle mass in active older persons has received less attention. Older individuals display a blunted muscle protein synthetic response to dietary protein ingestion. However, this reduced anabolic response can largely be overcome when physical activity is performed in close temporal proximity to protein consumption. Moreover, recent evidence has helped elucidate the optimal type and amount of dietary protein that should be ingested by the older adult throughout the day in order to maximize the skeletal muscle adaptive response to physical activity. Evidence demonstrates that when these principles are adhered to, muscle maintenance or hypertrophy over prolonged periods can be further augmented in active older persons. The present review outlines the current understanding of the role that dietary protein occupies in the lifestyle of active older adults as a means to increase skeletal muscle mass, strength and function, and thus support healthier aging.

Fig. 1

Schematic representation of the relative muscle protein synthetic (MPS) response to the ingestion of a single protein bolus in elderly individuals. A 20 g dose of casein protein is taken as a control/normal response due to its resemblance to the protein content found in a ‘normal meal’ (in terms of protein quantity, digestion and absorption kinetics, and amino acid profile) and is given an arbitrary ‘100 %’ value. Thereafter, bars refer to the relative modulations (either increase or decrease) from ‘normal’ (i.e., 100 %) by different interventions, details of which are reported on the x axis. Data were extrapolated from numerous studies performed within our laboratory [27, 51, 52, 65, 89, 96, 97]. Note: wherever possible, the 100 % control response for each intervention is obtained from the values obtained within that specific study. CHO carbohydrate