Bone · VITD-BONE-01 · v2
Several large, well-conducted trials gave ordinary adults a daily or monthly vitamin D supplement or a dummy pill and then counted broken bones. The biggest, with 25,871 people [4], found the same number of fractures in both groups, and smaller trials in older adults [3], in healthy New Zealanders [5], and in a mostly South Asian population [19] all reached the same answer. A related trial also found no reduction in falls [9], the main way vitamin D was thought to protect bones. So the evidence here does not show that vitamin D prevents fractures in the general population, and in the strongest study the numbers point slightly the other way. The panel noted one real limit: none of these trials deliberately enrolled people who were severely vitamin-D-deficient, so they cannot speak to that group.
Every directly on-target general-adult trial reports no fracture reduction. The largest and most precise, [4] (N=25,871, participants not recruited for deficiency), found hazard ratios of 0.98 (95% CI 0.89 to 1.08) for total fractures, 0.97 (0.87 to 1.07) for nonvertebral, and 1.01 (0.70 to 1.47) for hip, with no effect modification by baseline 25-hydroxyvitamin D. [3] found no effect on nonvertebral fractures in adults aged 70 or older, and [5] reported a fracture HR of 1.19 (0.94 to 1.50) under monthly bolus dosing. [19], with fracture as its primary endpoint, reported HR 1.06 (0.57 to 1.99). [9], in the same cohort as [4], found no reduction in falls (OR 0.97, 0.90 to 1.05). The contested point: The evidence does not divide on whether unselected adults benefit — the trials agree they do not. The one open edge is the frankly vitamin-D-deficient subgroup: these trials enrolled largely replete participants ([9] baseline 25(OH)D 77 nmol/L) and did not target deficiency, so they bound rather than address that question.
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One reviewer's only job is to attack the finding. The challenges below were weighed before the grade was set.
The claim as worded is contradicted, not merely unsupported: the largest on-target RCT [4] and its sibling [9] enrolled adults not selected for deficiency (replete at baseline), and all point estimates sit at or above 1.0 — there is no reduction to report.
The corpus cannot address frankly vitamin-D-deficient subgroups, where a benefit might exist; the null trials explicitly did not target deficiency. This bounds but does not rescue a claim about 'general adults'.
Where it remains uncertain. None of the null trials enrolled frankly deficient adults, so the corpus cannot exclude a benefit confined to that subgroup.
Aleatory
[19] accrued only 20 versus 19 fracture events, yielding a wide CI (0.57 to 1.99) driven by chance in a low-event setting.
Epistemic
No trial in the corpus enrolled frankly vitamin-D-deficient adults; [4] showed no modification by baseline 25(OH)D but did not sample a deficient population, leaving that question unmeasured.
Inferential
[9] measures falls, not fractures, so its support for the null rests on the mechanistic link between falls and fractures rather than on a fracture outcome.
The load-bearing papers from a corpus of 20, each classified by what it does to the claim. Every DOI is taken from the corpus the claim was graded on.
Independent RCT in adults >=70 confirms no effect on nonvertebral fracture incidence
“No effects were found on the outcomes of SPPB, MoCA, and incidence of nonvertebral fractures”
Panel auditInternal validity: high · scope of inference: Generally healthy adults aged 70+ without major comorbidities, nonvertebral fractures over 3 years.Key limitations: nonvertebral fractures only · age 70+ not general adults · low fracture rate limits power
Decisive null in generally healthy adults not selected for deficiency; CI excludes meaningful benefit
“Supplemental vitamin D3, as compared with placebo, did not have a significant effect on total fractures (which occurred in 769 of 12,927 participants in the vitamin D group and in 782 of 12,944 participants in the placebo group; hazard ratio, 0.98; 95% confidence interval [CI], 0.89 to 1.08; P = 0.70), nonvertebral fractures (hazard ratio, 0.97; 95% CI, 0.87 to 1.07; P = 0.50), or hip fractures (hazard ratio, 1.01; 95% CI, 0.70 to 1.47; P = 0.96)”
Panel auditInternal validity: high · scope of inference: Generally healthy men 50+ and women 55+ not selected for deficiency, low bone mass, or osteoporosis.Key limitations: not selected for vitamin D deficiency · fractures self-reported before adjudication
Null in a healthy ambulatory adult cohort with a different dosing regimen
“High-dose bolus vitamin D supplementation of 100 000 IU colecalciferol monthly over 2·5-4·2 years did not prevent falls or fractures in this healthy, ambulatory, adult population.”
Panel auditInternal validity: high · scope of inference: Healthy ambulatory adults aged 50-84 in New Zealand, non-vertebral fractures with bolus monthly dosing.Key limitations: bolus monthly dosing may differ from daily · non-vertebral fractures a secondary outcome · point estimate numerically above 1
3 of 20 papers shown. The full review lists all of them, with the panel’s arbitration →
Claims are graded at each quarterly release, and re-graded between releases only when a pivotal trial lands. Every change is a new version of the claim.
Direct, large, precise RCT evidence in the claim's exact population shows point estimates at or above 1.0 with CIs excluding meaningful benefit, so a reduction is refuted (while the corpus leaves open a possible benefit in frankly deficient subgroups it did not test).
Release 2026-q4 re-graded every claim from its corpus under protocol v0.19. An earlier release's grade is shown for the record; it came from an earlier protocol and is not a movement.
Assumptions that carry weight but are not themselves established.
The panel records the gap that would most move the claim, and the study that would close it.
Fracture trial in frankly deficient adults. Every null trial enrolled largely replete participants ([9] baseline 25(OH)D 77 nmol/L); the one population where benefit is biologically plausible is unmeasured. The panel rates this the highest-importance open gap for the claim, and names the study design that would close it: A placebo-controlled RCT enrolling only adults with baseline 25(OH)D below a deficiency threshold, with incident fracture as the primary endpoint.
Open question: Does vitamin D supplementation reduce fractures specifically in adults who are frankly vitamin-D-deficient at baseline? Why it is still open: The null trials [4], [3], [5], [9] enrolled participants not selected for deficiency and explicitly did not target it, so the corpus cannot address this subgroup.
Priors is a sceptical first reader, not peer review, and not medical advice.
Release 2026-q4 · graded 26 Oct 2026 · protocol v0.19