Nutritional strategies for maintaining muscle mass and strength from middle age to later life: A narrative review.

Abstract

Objective: To determine evidence on the role of dietary intake and nutritional supplementation in maintaining muscle mass and strength from midlife through old age. Method(s): PubMed and Cochrane databases were searched to identify original research including observational studies of dietary intake and nutritional interventions for sustaining muscle mass and strength. Result(s): Progressive age-related reductions in muscle mass/strength (i.e., sarcopenia) can cause substantial morbidity. The benefits of exercise, particularly progressive resistance training, to muscle mass and strength with/without dietary interventions are well documented. Protein and amino acid (particularly leucine) intake should be considered, and supplementation may be warranted for those not meeting recommended intakes. Other nutrients may contribute to sustaining/improving muscle mass and strength. Vitamin D receptors are expressed in muscle tissue; meta-analyses have shown that vitamin D benefits muscle strength. Data suggest that milk and other dairy products containing different bioactive compounds (i.e., protein, leucine) can enhance muscle protein synthesis, particularly combined with resistance exercise. Omega-3s can improve muscle mass and strength by mediating cell signaling and inflammation-related oxidative damage, but no studies were specifically conducted in sarcopenia. Low-dose antioxidants (e.g., vitamins C and E) can protect muscle tissue from oxidative damage, but relevant studies are limited. Magnesium is involved with muscle contraction processes and data have shown benefits to muscle strength. Acidogenic diets (e.g., limited fruits/vegetables) increase muscle protein breakdown, which is exacerbated by aging. Supplementation with alkalizing compounds (e.g., bicarbonates) can promote muscle strength. Small studies of probiotics and plant extracts have generated interest, but few large studies have been conducted. Conclusion(s): Based on available data, dietary and supplemental interventions may add to benefits of exercise on muscle mass and strength; effects independent of exercise have not been consistently shown.