Association between vitamin D supplementation and fracture incidence in community-dwelling older adults: an updated systematic review and meta-analysis of randomized controlled trials

Abstract

Previous studies have reached different conclusions regarding the effect of vitamin D supplementation and the incidence of fractures in the elderly. As more and more high-quality studies are published, an updated Meta-analysis is needed. We searched the PubMed, Cochrane Library, Embase, and Web of Science databases (from creation date to September 10, 2022) using the keywords vitamin D and fracture. We also searched at https://clinicaltrials.gov/ to search for unpublished clinical studies. Randomized clinical trials comparing vitamin D supplements with a placebo or no treatment for fracture incidence in community-dwelling adults older than 50 years was included. Hip fracture was defined as the primary outcome. Secondary outcomes were total fracture, vertebral fracture, and nonvertebral fracture. The protocol is available in PROSPERO (ID: CRD42022360619). A total of 15 randomized trials involving 53291 participants fulfilled the inclusion criteria. Supplementing with vitamin D had no significant effect on reducing the incidence of hip fracture (RR = 1.18, [95% CI, 0.99 − 0.41]), total fracture (RR = 1.01, [95% CI, 0.92–1.11]), vertebral fracture (RR = 0.97, [95% CI, 0.54–1.77]), or non-vertebral fracture (RR = 1.04, [95% CI, 0.97–1.12]). On the contrary, taking high doses of vitamin D once a year may increase the incidence of hip fractures (OR = 1.44, [95% CI, 1.03–2.02]). Besides, being in a low-light environment increased the incidence of hip fractures (OR = 1.25, [95% CI, 1.01–1.55]). There were no significant findings from subgroup analyses based on sex, fracture history, calcium consumption, baseline 25-hydroxyvitamin levels, or trial durations. Vitamin D use in community-dwelling older adults does not reduce the risk of fracture. High doses of vitamin D at one-year intervals may even increase the risk of fracture. In addition, older adults in low sunlight exposure areas had a higher risk of fracture regardless of vitamin D use.