(HealthDay News) — High doses of vitamin D do not appear to protect postmenopausal women from osteoporosis, according to research published online in JAMA Internal Medicine.

Karen Hansen, M.D., an associate professor of medicine at the University of Wisconsin School of Medicine and Public Health in Madison, and colleagues focused on 230 vitamin-D deficient postmenopausal women. Most were white, and all were under the age of 75. Between 2010 and 2013, the women were divided into three groups: a high-dose vitamin D group; a low-dose vitamin D group; and a placebo group. For one year, those in the low-dose group received 800 international units (IU) of vitamin D daily, while those in the high-dose group received 50,000 IU of vitamin D twice a month.

The researchers found that by year’s end, the no-dose group saw their calcium absorption rate drop by 1.3%, while the low-dose groups experienced a decrease of 2%. In comparison, the high-dose group saw their rate increase by 1%. While the overall vitamin D level across all three groups was ultimately measured at 21 ng/mL, the high-dose group saw their levels rise to 30 ng/mL.

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But despite the differences, tests revealed that the high-dose group showed no advantage over either the low-dose or no-dose group with respect to spine health, total bone mineral density, overall muscle mass, or physical mobility. Similarly, no differences between the groups were seen with respect to overall fall risk. The researchers cautioned that the findings may not apply to non-white women, young adults, women over the age of 75, or men.

One author disclosed financial ties to Takeda Pharmaceuticals.


  1. Hansen, KE; Johnson, RE; Chambers, KR; et al. JAMA Intern Med. published online August 03, 2015. doi:10.1001/jamainternmed.2015.3874
  2. Deborah Grady. JAMA Intern Med. published online August 03, 2015; doi:10.1001/jamainternmed.2015.3937.