Long-chain n-3 polyunsaturated fatty acid ingestion for the stimulation of muscle protein synthesis in healthy older adults

Abstract

This review aims to critically evaluate the efficacy of long-chain ո-3 polyunsaturated fatty acid (ո-3 PUFA) ingestion in modulating muscle protein synthesis (MPS), with application to maintaining skeletal muscle mass, strength and function into later life. Ageing is associated with a gradual decline in muscle mass, specifically atrophy of type II fibres, that is exacerbated by periods of (in)voluntary muscle disuse. At the metabolic level, in otherwise healthy older adults, muscle atrophy is underpinned by anabolic resistance which describes the impaired MPS response to nonpharmacological anabolic stimuli, namely physical activity/exercise and amino acid provision. Accumulating evidence implicates a mechanistic role for n-3 PUFA in upregulating MPS under stimulated conditions (postprandial state or following exercise) via incorporation of eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) into the skeletal muscle phospholipid membrane. In some instances, these changes in MPS with chronic ո-3 PUFA ingestion have translated into clinically relevant improvements in muscle mass, strength and function; an observation evidently more prevalent in healthy older women than men. This apparent sexual dimorphism in the adaptive response of skeletal muscle metabolism to EPA and DHA ingestion may be related to a greater propensity for females to incorporate ո-3 PUFA into human tissue and/or the larger dose of ingested ո-3 PUFA when expressed relative to body mass or lean body mass. Future experimental studies are warranted to characterise the optimal dosing and duration of ո-3 PUFA ingestion in order to prescribe tailored recommendations regarding n-3 PUFA nutrition for healthy musculoskeletal ageing into later life.