Vitamin D Supplements: Bone Health or Bogus?

Vitamin D supplements did not improve bone mineral density in healthy adults

/ Author:  / Reviewed by: Joseph V. Madia, MD Beth Bolt, RPh

(RxWiki News) Many people start to take vitamin D supplements to keep their bones strong as they age. But do these supplements really work, or are they a waste of money?

Researchers recently looked at past clinical trials that tested whether vitamin D supplements helped improve bone density, an important measure of bone strength and health.

They found that vitamin D supplements did not typically improve bone density for people who already had normal levels of vitamin D. Although bone density improved somewhat in the femur, the rest of the body, including the hips and spine, did not become more dense.

The authors of this review suggested that most older adults who are healthy don't need to take vitamin D as a preventive measure.

"Tell your doctor about the supplements you are taking."

Ian Reid, MD, of the Department of Medicine at the University of Auckland, and two colleagues conducted this review to see if vitamin D supplements affected bone mineral density.

Vitamin D is often called the "sunshine vitamin" because it is produced naturally in the body when the skin is exposed to sunlight. Vitamin D helps the body absorb calcium.

Sometimes, vitamin D supplements are recommended to older adults to help with bone mineral density, although there is not much evidence showing that vitamin D supplements improve bone health.

This review examined previous studies for evidence of vitamin D supplements improving bone health. Specifically, the review was looking for changes in bone mineral density.

A healthy bone density is important for preventing fractures, especially in old age when bones often become weaker and brittle.

The researchers included 23 studies in the review, each with an average length of 23.5 months. A total of 4,082 patients, with an average age of 59 years, participated in the studies.

A total of 18 of the studies involved comparison groups taking placebos, or fake supplements, to compare to the effects of vitamin D supplements.

The studies included in the review had differing vitamin D regiments. The doses of vitamin D, as well as the length of the treatment, varied. On average, 500 IU was the daily dose in six of the studies, 500-799 IU was used in four studies, and 800 IU or more was used in 13 studies.

In each of the studies, bone density was measured in one to five locations of the body, including lower spine, femoral neck (the area of the femur between the long part of the bone and where it inserts into the hip), hip and forearm. Some studies measured bone density in the entire body.

The researchers found that there was no significant effect of vitamin D on bone density in the spine, hip, forearm, or total body scans. There was a significant increase in bone density in the femoral neck.

Of the 23 studies, only five had positive outcomes of improved bone density. Three of those studies had participants who were on average somewhat deficient in vitamin D.

Additionally, of the studies that did report improved bone density, the improvement was not significant enough to prevent a bone from fracturing after a fall, according to the researchers.

They also found that doses of less than 800 IU per day were more effective for improving bone density in the spine.

The researchers concluded that taking vitamin D did not provide any benefit to people with healthy levels of vitamin D, so the use of vitamin D supplements was not necessary for most older adults.

According to the researchers, rather than advising that all older people take vitamin D supplements to protect their bones, healthcare professionals should target people who may not be getting enough vitamin D naturally, like those who do not receive very much exposure to sunlight.

Additionally, they said that the dose of vitamin D matters: more vitamin D was not always better for bone density in the studies. They called for more research to be conducted on appropriate doses of vitamin D supplements.

This review was published in The Lancet on October 10.

The research was funded by the Health Research Council of New Zealand. The authors reported no conflicts of interest.

Review Date: 
October 10, 2013
Last Updated:
October 11, 2013