Vitamin D supplements have not been shown to prevent fractures in previous studies, possibly due to insufficient dosage or targeting non-deficient populations. This meta-analysis reviewed 23 randomized controlled trials with over 4000 participants to determine if vitamin D supplementation affects bone mineral density. It found a small increase in bone mineral density at the femoral neck of 0.8% but no significant effects at other sites like the total hip. The results suggest that widespread use of vitamin D supplements for osteoporosis prevention in generally healthy and non-deficient adults is inappropriate.