25-hydroxyvitamin D level is associated with greater grip strength across adult life span: a population-based cohort study

Abstract

Objective Maintaining muscle function throughout life is critical for healthy ageing. Although in-vitro studies consistently indicate beneficial effects of 25-hydroxyvitamin D (25-OHD) on muscle function, findings from population-based studies remain inconclusive. We therefore aimed to examine the association between 25-OHD concentration and handgrip strength across a wide age range, and assess potential modifying effects of age, sex and season. Methods We analysed cross-sectional baseline data of 2,576 eligible participants out of the first 3,000 participants (recruited from March 2016 to March 2019) of the Rhineland Study, a community-based cohort study in Bonn, Germany. Multivariate linear regression models were used to assess the relation between 25-OHD levels and grip strength, while adjusting for age, sex, education, smoking, season, body mass index, physical activity levels, osteoporosis and vitamin D supplementation. Results Compared to participants with deficient 25-OHD levels (<30 nmol/L), grip strength was higher in those with inadequate (30 to <50 nmol/L) and adequate (≥50 to ≤125 nmol/L) levels (ßinadequate=1.222 [95%CI: 0.377; 2.067], p=0.005; ßadequate=1.228 [95%CI: 0.437; 2.019], p=0.002). Modeling on a continuous scale revealed grip strength to increase with higher 25-OHD levels up to ~100 nmol/L, after which the direction reversed (ßlinear=0.505, [95%CI: 0.179; 0.830], p=0.002; ßquadratic=-0.153 [95%CI: -0.269; -0.038], p=0.009). Older adults showed weaker effects of 25-OHD levels on grip strength than younger adults (ß25OHDxAge=-0.309, [95%CI: -0.594; -0.024], p=0.033). Conclusions Our findings highlight the importance of sufficient 25-OHD levels for optimal muscle function across the adult lifespan. However, vitamin D supplementation should be closely monitored to avoid detrimental effects.

Vitamin D: The Challenge of Bridging the Gap and the Rationale for Supplementation

“…Both skeletal muscle atrophy and poor muscle function are consequences of low vitamin D status [42] This is likely because vitamin D deficiency reduces oxygen consumption and causes disruption of mitochondrial function [43]. Hand grip strength is higher in those with 25(OH)D levels from 30 to <50 nmol/L and ≥50 to ≤125 nmol/L than in people who are deficient [44]. Poor muscle function increases the risk of falls and low vitamin D status has been linked with poor gait and balance in older people [45] as well as falls [46].…”