Short answer: Not in healthy adults who are not low in vitamin D, in the largest trial. VITAL gave 25,871 adults aged 50 and older either 2,000 IU of vitamin D3 a day or placebo for a median of 5.3 years: total, hip and non-spine fractures were the same in both groups. NIH says calcium plus vitamin D lowered fractures in older people living in care homes, but evidence in people living at home is mixed.
The Vitamin D and Omega-3 Trial enrolled men 50 and older and women 55 and older across the US. It was not limited to people with low vitamin D, low bone density or osteoporosis. A bone study within it (LeBoff 2022) counted fractures confirmed by medical records.
| Fracture type | Hazard ratio | Meaning |
|---|---|---|
| Any fracture | 0.98 (769 of 12,927 vs 782 of 12,944 people) | No difference |
| Non-spine fractures | 0.97 | No difference |
| Hip fractures | 1.01 | No difference |
The result did not change by age, sex, race, weight or starting vitamin D level. The NIH Office of Dietary Supplements (ODS) adds that it also did not change in people taking calcium, at high fracture risk, or with a past fragility fracture. Only 2.4% of the people started with a 25-hydroxyvitamin D level below 12 ng/mL, so very few were truly deficient.
ODS says trials of vitamin D with calcium give small gains in bone mineral density in postmenopausal women and older men, and help reduce fractures in older people living in institutions. For people living at home the picture is mixed: one pooled analysis of six trials in 49,282 older adults found calcium plus vitamin D lowered any fracture by 6% and hip fracture by 16%, while a review of 11 trials of vitamin D alone found no protection. The US Preventive Services Task Force (USPSTF), reviewing 11 trials in 51,419 healthy adults 50 and older, found the evidence insufficient to judge supplements for preventing fractures, and recommended against 400 IU or less of vitamin D with 1,000 mg or less of calcium for that purpose. ODS also reports the USPSTF concluded with moderate certainty that vitamin D does not reduce falls in adults 65 and older living at home without deficiency or osteoporosis.
This is a different situation. Medicines such as Prolia, Reclast and Fosamax can lower blood calcium, and their labels ask for enough calcium and vitamin D during treatment. VITAL does not change that; it tested vitamin D as a stand-alone way to prevent fractures in healthy people. See calcium and vitamin D with bone medicines for the label amounts.
For someone with osteoporosis, the bone medicine labels report their own fracture trials. Dose Track can keep a daily vitamin D reminder next to a weekly, monthly or 6-monthly bone medicine.
Read more on Dose Track: Vitamin D3 · Osteoporosis · Hazard ratio · Prolia side effects