Read the fine print: Calcium supplement studies
Two studies — one in the Lancet, one in the British Medical Journal — have reported that calcium and vitamin D supplements don't prevent fractures. This sounds like another health news about-face: These supplements have long been touted as a good way to keep bones strong, and many previous studies have shown just the opposite — that they do help prevent fractures. So how could two large studies, published in important medical journals, reach the opposite conclusion?
This is really a lesson in careful reading. The headlines got the broad brushstroke right: Both studies did find that after about two years, people randomly assigned to take calcium and vitamin D had just as many fractures as those who took placebo pills.