Vitamin D and falls in older adults: the conflicting STURDY and VITAL trial record

For two decades, vitamin D was sold to older adults as a one-pill fall-prevention strategy. The evidence base supporting that claim has not aged well. Three of the largest controlled trials ever run on vitamin D, completed between 2020 and 2024, give an answer that is more confusing than reassuring — and one of them found higher doses actually increased the rate of falls.

What the early observational signal suggested

The original enthusiasm came from meta-analyses of small trials in the 2000s suggesting a 14–20% reduction in falls with vitamin D 800 IU/day in institutionalised older adults (PMID: 19797342).¹ These were largely in vitamin D-deficient nursing home residents, and the magnitude of effect tracked closely with how deficient the baseline population was. The American Geriatrics Society incorporated this into a 2010 clinical practice guideline recommending routine 800 IU supplementation in adults aged 65 and over to prevent falls.

STURDY: more is not better

The STURDY trial, published in 2020, randomised 688 community-dwelling adults aged 70 and over with baseline 25(OH)D levels of 10–29 ng/mL to one of four doses of vitamin D3: 200, 1,000, 2,000, or 4,000 IU/day for two years (PMID: 33196346).² Compared with the 200 IU reference dose, the higher doses showed no reduction in time-to-first-fall and a numerically higher risk of falls at 1,000–4,000 IU. The trial was stopped early for futility and a possible safety signal. The conclusion — that escalating vitamin D dose did not produce escalating benefit — directly contradicted the dose-response logic that had driven over-the-counter formulations toward 5,000 and 10,000 IU capsules.

VITAL: no effect in the general population

VITAL randomised 25,871 adults aged 50 and over to 2,000 IU/day vitamin D3 or placebo for a median 5.3 years. The pre-specified ancillary analysis of falls and fractures, published in 2022, found no reduction in the rate of total fractures, hip fractures, or non-vertebral fractures (PMID: 35939535).³ A separate fall analysis showed no effect on incidence of falls or injurious falls.⁴ Notably, this was a generally vitamin D-replete population — mean baseline 25(OH)D was 30 ng/mL — and supplementation could not reduce an event rate already at the population floor.

D-Health and high-dose monthly bolus

The Australian D-Health trial randomised 21,315 adults aged 60–84 to 60,000 IU monthly vitamin D3 or placebo for five years and similarly found no reduction in falls, fractures, or all-cause mortality (PMID: 35792080).⁵ Combined with earlier signals that very large annual boluses can paradoxically increase fall rates (PMID: 20460620), the modern picture is that intermittent megadosing does not work and may harm.⁶

What 2024 meta-analyses now conclude

A 2024 Cochrane update that incorporated STURDY, VITAL, and D-Health concluded the evidence does not support routine vitamin D supplementation for fall prevention in community-dwelling older adults with 25(OH)D above 12 ng/mL (PMID: 38629440).⁷ For adults with deficiency (under 12 ng/mL), modest supplementation to reach 20–25 ng/mL remains supported, but the goal is correcting deficiency rather than achieving any specific "optimal" level. The USPSTF in 2024 explicitly recommended against vitamin D supplementation for fall prevention in community-dwelling adults aged 60 and over without a documented deficiency or osteoporosis (PMID: 39189913).⁸

What this means for adults choosing a dose

A reasonable 2026 framework: test 25(OH)D before supplementing, correct levels under 20 ng/mL with 1,000–2,000 IU/day, and stop chasing higher targets without a clinical reason. The era of recommending 4,000 IU as a universal "longevity dose" is over. Anyone over 70 who is already supplementing and still falling should have their gait, vision, blood pressure, and medication list reviewed — falls in this age group are multifactorial, and a single nutrient was never the right lever.