11 Oct 2013 --- Taking vitamin D supplements does not improve bone mineral density at the total hip, spine, forearm, or in the body as a whole, a large meta-analysis involving more than 4,000 healthy adults published in The Lancet has found. With close to half of adults aged 50 and older using vitamin D supplements, the authors conclude that continuing widespread use of these supplements to prevent osteoporosis in healthy adults is needless.