The effect of vitamin D plus protein supplementation on sarcopenia: A systematic review and meta-analysis of randomized controlled trials

Abstract

PurposeThe exact effect of vitamin D supplementation, either as monotherapy or in combination with protein, on musculoskeletal health in patients with sarcopenia is currently unknown. This study aimed to determine the effect of vitamin D alone or with protein supplementation on muscle strength, mass, and performance in this population. MethodsA comprehensive search was conducted in Medline, Cochrane Central and Scopus databases, up to March 31st, 2020. Data were expressed as standardized mean difference (SMD) with 95 % confidence intervals (CI). I2 index was employed for heterogeneity. ResultsThe initial search identified 1164 studies, eight of which met the eligibility criteria for qualitative and quantitative analysis, yielding a total of 776 patients. Vitamin D (100–1600 IU/day) plus protein (10–44 g/day) supplementation exhibited a beneficial effect on muscle strength, as demonstrated by an improvement in handgrip strength (SMD 0.38 ± 0.07, 95 % CI 0.18–0.47, p = 0.04; I2 76.2 %) and a decrease in the sit-to-stand time (SMD 0.25 ± 0.09, 95 % CI 0.06–0.43, p = 0.007; I2 0%) compared with placebo. However, the effect on muscle mass, assessed by skeletal muscle index, was marginally non-significant (SMD 0.25 ± 0.13, 95 % CI -0.006–0.51, p = 0.05; I2 0%). No effect on appendicular skeletal muscle mass or muscle performance (assessed by walking speed) was observed with vitamin D plus protein. ConclusionsVitamin D supplementation, combined with protein, improves muscle strength in patients with sarcopenia, but has no effect on muscle mass or performance.