Higher Vitamin D Levels During Menopause May Reduce Fracture Risk

Women with higher vitamin D levels during menopause may have a decreased risk for fracture, new data presented at the American Society for Bone and Mineral Research (ASBMR) 2014 Annual Meeting suggest.

In an analysis of 1,620 women enrolled in the bone cohort of the Study of Women’s Health Across the Nation (SWAN), researchers found that each 10-ng/mL increase in 25-hydroxyvitamin D (25[OH]D) was linked to a 25% reduction in the risk for fracture. This result held even after adjustment for BMI, bone mineral density (BMD) and other confounders.

Further, results indicated that fracture risk was 42% lower in women with 25(OH)D levels exceeding 20 ng/mL, which remained unchanged after exclusion of women who were already postmenopausal at their second clinic visit.

Women attended up to 11 clinic visits during an average of 9.5 years, according to the Jane Cauley, DrPH, of the University of Pittsburgh Graduate School of Public Health, and colleagues. They measured 25(OH)D at the 2-year visit.

After the 2-year visit, incident nontraumatic fractures were identified at each annual visit by self-report and subsequent confirmation with radiographic findings, according to the researchers. Eighty-eight women experienced nontraumatic fractures.

Researchers also evaluated BMD across the menopausal transition in 791 women for whom a final menstrual period could be determined by comparing rates of changes in BMD at the spine and hip over time. Specifically, they looked at rates from 1 to 5 years prior to final menstrual period, from 1 year before to 2 years after final menstrual period and 2 to 5 years after final menstrual period.

They observed no link between 25(OH)D and transmenopausal bone loss

Mean 25(OH)D level was 21.2 ng/mL in this subgroup, which was on par with that of all women in the study.

Most women (74.5%) were premenopausal or early menopausal, 7.2% were late menopausal and 4.8% were postmenopausal.

At the 2-year visit, mean 25(OH)D level was 21.6 ng/mL but varied significantly according to race/ethnicity. White women had a mean level of 25.2 ng/mL, black women had a mean level of 14.1 ng/mL, Chinese women had a mean level of 20.1 ng/mL and Japanese women had a mean level of 23.5 ng/mL (P<.001), according to the data.

Of all participants, 43% had 25(OH)D levels lower than 20 ng/mL.

Mean age at measurement was 48.5 years and did not vary by race/ethnicity. BMI, however, was significantly different, with black women having a mean BMI of 31.8 and white women having a BMI of 28.2. Japanese and Chinese women had the lowest BMIs at 23.5 and 23.2, respectively.

“We conclude that women with higher 25(OH)D levels at midlife have a lower risk of subsequent fractures.  Vitamin D supplementation may be warranted in women with 25(OH)D  <20 ng/mL,” the researchers wrote in an abstract.

Reference

1. Cauley J et al. Abstract 1076. Presented at: American Society for Bone and Mineral Research 2014 Annual Meeting; Sept. 12-15, 2014; Houston, Texas.