Effect of Vitamin D Supplementation on Risk of Fractures and Falls According to Dosage and Interval: A Meta-Analysis

BACKGROUND: Although recent studies comparing various dosages and intervals of vitamin D supplementation have been published, it is yet to be elucidated whether there is an appropriate dose or interval to provide benefit regarding fracture risk. We aimed to assess the published evidence available to date regarding the putative beneficial effects of vitamin D supplements on fractures and falls according to various dosages and intervals. METHODS: We performed a meta-analysis of randomized controlled studies reporting associations between vitamin D supplementation and the risks of fractures and falls in PubMed, EMBASE, and Cochrane library. Studies with supplements of ergocalciferol or calcitriol, those with a number of event ≤10, or those with a follow-up duration of less than 6 months were also excluded. RESULTS: Thirty-two studies were included in the final analysis. Vitamin D supplementation with daily dose of 800 to 1,000 mg was associated with lower risks of osteoporotic fracture and fall (pooled relative risk [RR], 0.87; 95% confidence interval [CI], 0.78 to 0.97 and RR, 0.91; 95% CI, 0.85 to 0.98), while studies with <800 or >1,000 mg/day did not. Also, among intervals, daily administration of vitamin D was associated with the reduced risk of falls, while intermittent dose was not. Also, patients with vitamin D deficiency showed a significant risk reduction of falls after vitamin D supplementation. CONCLUSION: Daily vitamin D dose of 800 to 1,000 IU was the most probable way to reduce the fracture and fall risk. Further studies designed with various regimens and targeted vitamin D levels are required to elucidate the benefits of vitamin D supplements.