Vitamin D, Calcium Shown to Reduce Mortality — Even Among Those With Hip Fractures

Nancy A. Melville

September 17, 2009

September 17 (Denver, Colorado) — Vitamin D and calcium have been shown to help lower mortality risk among older people, but the benefits are not necessarily explained by a reduced risk for hip fracture, according to a study presented here at the American Society for Bone and Mineral Research 31st Annual Meeting.

The Women's Health Study (WHI) was perhaps the most prominent study to demonstrate the benefits of vitamin D and calcium in reducing mortality in postmenopausal women.

Logic suggests that the benefits are at least partially attributable to a reduction in the risk for hip fractures and the serious complications that can accompany them, but that doesn't appear to be the case, said Bo Abrahamsen, MD, PhD, chief physician of endocrinology and professor in clinical database studies and health registers at Gentofte Hospital and the University of Southern Denmark.

"Hip fractures are known to be preventable to a small extent by vitamin D and calcium, and these fractures have great mortality, with some 20% of women and 30% of men dying in the first year after such a fracture," said Dr. Abrahamsen, who was lead author of the study. "However, we found that vitamin D and calcium reduced mortality even among patients who suffered such fractures."

In evaluating the role of calcium in the effect of vitamin D on mortality, the researchers merged patient variables from 5 major European randomized fracture trials that evaluated patients who took calcium and vitamin D and those who took vitamin D alone.

The studies involved a total of 28,710 participants with a mean age of 77.7 years. The Danish team's analysis covered 3283 within-study deaths over 36 months.

The results offered further evidence of the benefits of vitamin D and calcium on mortality risk reduction. When given with vitamin D, calcium reduced mortality (hazard ratio [HR], 0.88 [0.81–0.97]; P < .01), whereas studies involving vitamin D alone showed no significant reduction in mortality (HR, 0.95 [0.85–1.05]; P = .28).

The reduction in mortality was significant even when patients who sustained hip fractures during the course of the study were excluded. The effects were greater among patients younger than 75 years, and no differences were observed related to sex or fracture history.

"We were not surprised by the results, as a similar reduction in mortality was found in the WHI study, but as food fortification policies for vitamin D are different in Europe, it was encouraging to be able to confirm the same effect size in European fracture studies," Dr. Abrahamsen said.

Limitations of the study included the fact that many of the contributing studies had a sizeable number of patients who did not adhere to therapy; however, that was also the case in the WHI study. Another limitation was th fact that the different studies used different ways of collecting death information, he noted.

Scientists have offered numerous theories on how vitamin D benefits the body, and the study provides important new insights into they way calcium can improve those benefits, said Cathleen Colon-Emeric, MD, associate professor of medicine at the Duke University Medical Center in Durham, North Carolina.

"We have had evidence for several years now that vitamin D supplementation seems to reduce mortality to a small but significant amount in older adults," said Dr. Colon-Emeric, who cited a study demonstrating that (Arch Intern Med. 2007;167:1730-1737).

"What hasn't been clear is whether it needs to be given with calcium, and whether the benefit is due to a reduction in major fractures or to its extraskeletal effects. The authors' analysis suggests that the benefit is larger when given with calcium, and is not explained by a reduction in fractures alone," Dr. Colon-Emeric said in an interview with Medscape Ob/Gyn & Women's Health during the meeting.

Studies have described vitamin D receptors in many tissues in the body and have suggested benefits ranging from lower blood pressure and fewer cardiovascular events to a reduction in certain kinds of cancer and a reduction in fall risk; however, the true role of vitamin D in those and other benefits is still unknown, she said.

"I think the jury is still out on whether all these effects are truly due to vitamin D, and whether they explain the apparent mortality reduction," Dr. Colon-Emeric said.

"However, vitamin D appears to be quite safe, and we recommend calcium and vitamin D supplements to most adults over age 65 to reduce falls and fracture risk, and possibly to reduce mortality."

Dr. Abrahamsen has received consulting fees or other remuneration from Amgen, Novartis, Servier, and Nycomed, and is on the speaker's bureau for Eli Lilly. Dr. Colon-Emeric has disclosed no relevant financial relationships.

American Society for Bone and Mineral Research (ASBMR) 31st Annual Meeting: Abstract 1028. Presented September 12, 2009.

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