Is there sufficient evidence to supplement omega-3 fatty acids to increase muscle mass and strength in young and older adults?

Omega-3 (omega-3) is a polyunsaturated fatty acid with anti-inflammatory properties that presents three main forms: alpha-linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid. Recently, studies performed in both young and older adults suggest that omega-3 may improve gains in muscle mass and/or enhance physical function. Thus, the aim of this narrative review was to evaluate the current evidence of omega-3 intake/supplementation on muscle/lean mass (LM) and physical function in young and older adults, and draw research-based conclusions as to the practical implications of findings. We first assessed whether omega-3 intake is associated with muscle mass and strength (observational studies), and then sought to determine whether evidence shows that supplementation of omega-3 increases muscle protein synthesis, LM and strength in adults and older adults (interventional studies). The search was carried out in PubMed and Scopus databases for the periods between 1997 and November 2018. The following keywords were used alone and in combination: omega-3, fish oil, muscle protein synthesis, muscle mass, lean mass, body composition, and physical function. In general, the evidence is mixed as to the effects of omega-3 supplementation on muscle mass in sedentary young and older adults; the hypertrophic effects of supplementation when combined with resistance training remain equivocal. Moreover, there is conflicting evidence as to whether supplementation confers a beneficial effect on muscle function in older adults. Importantly, this conclusion is based on limited data and more studies are needed before omega-3 supplementation can be recommended as a viable strategy for such purposes in clinical practice. (C) 2019 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.