Combined vitamin D and calcium supplementation can reduce fracture risk but not necessarily cancer risk

Chung M, Lee J, Terasawa T, et al. Vitamin D with or without calcium supplementation for prevention of cancer and fractures: An updated meta-analysis for the U.S. Preventive Services Task Force Ann Intern Med. 2011;155:827-38.

Review question

What are the effects of vitamin D supplements with or without calcium on fractures and cancer in healthy older adults?

Background

Vitamin D and calcium are important for bone health. Vitamin D increases the uptake of calcium, which is the building block of bones. Vitamin D also improves muscle function; therefore it is doubly important in preventing fracture, since stronger muscles may help prevent falls.

Women are particularly at risk for fracture, as they lose bone mass at a faster rate than men do.

It has also been suggested that vitamin D may play a role in cancer prevention.

How the review was done

This summary is based on a meta-analysis that included 19 randomized controlled trials, 3 for cancer outcomes and 16 for fracture outcomes. Studies were published between 1992 and 2010.

There were over 100,000 participants combined in this analysis. Participants were healthy adults over the age of 65. Most of the participants were women. The studies followed participants for periods up to 7 years.

Vitamin D with or without calcium was compared against no treatment or placebo.

What the researchers found

Vitamin D with calcium was slightly more effective than a placebo in preventing factures, while Vitamin D supplementation without calcium was not more effective than a placebo in preventing fractures.

The effectiveness was greatest among institutionalized elderly persons, and smaller in community-dwelling elderly persons or postmenopausal women. There was no effect among community-dwelling women with a history of fracture. Effects did not differ by the dose of vitamin D taken or by the baseline blood concentration of Vitamin D. As a whole, the evidence is of mixed quality.

One study of postmenopausal women showed that Vitamin D supplementation was associated with a risk of kidney or urinary tract stones.

Conclusion

Combined vitamin D and calcium supplementation reduces fracture risk in older persons, but the ideal dosage is unclear.

The reviewers were unable to make a conclusion about cancer prevention.

Fracture rates among special populations