Does vitamin D prevent fractures?

What the trials found

The largest review is from 2026, in the BMJ. It pooled 69 trials with 153,902 adults who were not taking drugs for osteoporosis. In most of the trials, people lived at home (87%) and were not at high risk of fractures or falls (73%).^[1]

• Vitamin D alone, 36 trials with 92,045 people: the risk of any fracture did not change (risk ratio 1.00, high certainty).^[1]
• Vitamin D with calcium, 15 trials with 51,126 people: the risk was 9% lower (risk ratio 0.91, high certainty).^[1]
• Hip fractures, other fractures and falls: little to no effect from vitamin D, calcium or both.^[1]

The authors looked at how many fractures this would prevent in real numbers. By that measure, they judged all three options to give little to no benefit.^[1]

A 2019 review found the same split. In 11 trials with 34,243 people, vitamin D alone did not lower the risk.^[2] In 6 trials with 49,282 people, 400 to 800 IU of vitamin D with 1000 to 1200 mg of calcium a day gave 6% fewer fractures and 16% fewer hip fractures.^[2]

The VITAL trial gave 25,871 US men aged 50 or older and women aged 55 or older 2000 IU of vitamin D3 a day or a placebo. Over a median of 5.3 years, total, nonvertebral and hip fractures were as common in both groups.^[3] The result did not differ by the starting blood level of vitamin D.^[3]

Bone density

Bone density is how much mineral the bone holds. A 2014 review of 23 trials with 4082 people, lasting about 2 years on average, found a gain of 0.8% at the femoral neck, the top of the thigh bone. There was no change at the spine, the whole hip or the forearm.^[4]

Large single doses can do harm

One trial gave 2256 women aged 70 or older either 500,000 IU of vitamin D3 once a year, in autumn or winter, or a placebo, for 3 to 5 years.^[5] The vitamin D group had 15% more falls and 26% more fractures. Falls were 31% more common in the first 3 months after each dose.^[5]

Where it may still help

Severe deficiency makes bones soft: rickets in children, osteomalacia in adults. Enough vitamin D prevents both.^[6]

Clinical trials found that vitamin D with calcium lowered fracture rates in older people who live in care homes.^[6] The 2026 review found few trials in high-risk people and care home residents, so the answer for them is less certain.^[1]

What official bodies say

The US Preventive Services Task Force advises against 400 IU or less of vitamin D with 1000 mg or less of calcium to prevent fractures. This applies to healthy adults aged 50 or older who live at home.^[6] It could not judge higher doses.^[6]

Who should ask first

People with osteoporosis or a past fracture should ask their doctor. Most trials enrolled people at low risk.^[1] Calcium with vitamin D also has a cost. In a 7-year trial of 36,282 women, 1000 mg of calcium with 400 IU of vitamin D a day raised the risk of kidney stones by 17%.^[6]

What the trials gave: Vitamin D for fractures.^[2]