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

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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.