High Doses of Vitamin D May Result in a Decrease in Bone Density


A three-year study conducted by the University of Calgary has shown that there are no benefits in taking high doses of Vitamin D.

A three-year study conducted by the University of Calgary has shown that there are no benefits in taking high doses of Vitamin D.1

The purpose of the study was to assess the dose-dependent effect of vitamin D supplementation on volumetric bone mineral density (BMD) and strength. The clinical trial was conducted in a single center in Calgary, Canada from August 2013 to December 2017. 311 healthy adults without osteoporosis participated, all between the ages of 55 to 70 years old. Each participant had baseline levels of 25-hydroxyvitamin D (25[OH]D) of 30 to 125 nmol/L. The trial was double-blind and randomized.2

Of the 311 participants who were, 287 completed the study. Baseline, 3-month, and 3-year levels of 25(OH)D were 76.3, 76.7, and 77.4 nmol/L for the 400-IU group; 81.3, 115.3, and 132.2 for the 4,000-IU group; and 78.4, 188.0, and 144.4 for the 10,000-IU group.2

At trial end, radial volumetric BMD was lower for the 4,000 IU group and 10,000 IU group, compared with the 400 IU group with mean percent change in volumetric BMD of −1.2% (400 IU group), −2.4% (4000 IU group), and −3.5% (10 000 IU group).2

Tibial volumetric BMD differences from the 400 IU group were −1.8 mg HA/cm3 in the 4000 IU group and −4.1 mg HA/cm3 in the 10 000 IU group, with mean percent change values of −0.4% (400 IU), −1.0% (4000 IU), and −1.7% (10 000 IU).2

Among healthy adults, receiving treatment with Vitamin D for 3 years at a dose of 4,000 IU per day or 10,000 IU per day, compared with 400 IU per day, resulted in statistically significant lower radial BMD. Tibial BMD was significantly lower, only with the 10,000 IU per day dose. There were no significant differences in bone strength at either the radius or tibia. Overall, these findings do not support a benefit of high-dose vitamin D supplementation for bone health.2


  1. Vitamin D: how much is too much of a good thing?Science Dailywebsite. https://www.sciencedaily.com/releases/2019/09/190903134738.htm. Published September 3, 2019. Accessed September 4, 2019.
  2. Burt LA, Billington EO, Rose MS, Raymond DA, Hanley DA, Boyd SK. Effect of high-dose vitamin d supplementation on volumetric bone density and bone strength: a randomized clinical trial.JAMA. 2019;322(8):736—745. doi:10.1001/jama.2019.11889.
  3. Nessel, Jennifer. Family history of diabetes linked to increase bone density.Contemporary Clinic.https://contemporaryclinic.pharmacytimes.com/news-views/family-history-of-diabetes-linked-to-increased-bone-density. Published August 26, 2019.

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