Vitamin D supplements aren't what they are cracked up to be when it comes to improving bone health and preventing breaks. So says a new study that looked at data from 81 controlled trials that involved more than 53,000 people, CNN reports. "Our meta-analysis finds that vitamin D does not prevent fractures, falls, or improve bone mineral density, whether at high or low dose," says lead author Mark J. Bolland of the University of Auckland, adding that "clinical guidelines should be changed to reflect these findings." Vitamin D helps regulate the amount of calcium and phosphate in our bodies, per the BBC. Most of our vitamin D comes from exposure to sunlight. Healthcare providers have long recommended people take vitamin D supplements for a variety of reasons, such as improving bone density in older people and ensuring sufficient vitamin D intake during fall and winter months.
The study did find that vitamin D supplements could be helpful in some rare cases, such as rickets and osteomalacia (a severe vitamin D deficiency that results in bone softening). Not everyone is convinced by the overall finding that vitamin D supplementation is worthless, CNN notes. Some have pointed out that only 6% of the trials that were analyzed were done in populations where vitamin D deficiency is an issue, thus skewing the results. "The health benefits of vitamin D supplementation tend to be most marked in people who have the lowest vitamin D levels to start with," one medical professor says. Also, others say, some of the trials that were analyzed had too few participants, too low of dosages of vitamin D, and short treatment periods. (Read more scientific study stories.)