Supplement
Vitamin D
Vitamin D sits in an unusual position: deficiency is genuinely harmful and worth correcting, yet supplementing people who are not deficient has repeatedly failed to deliver the broad benefits observational studies once hinted at. The largest randomised trials have now directly tested whether supplementation extends life in generally healthy older adults.
Quick verdict
Large randomised trials in generally healthy older adults have found no reduction in overall mortality from routine vitamin D supplementation. Correcting a diagnosed deficiency remains standard medical advice — a different question from taking it for longevity.
The assessment
Claim by claim
Each claim is graded on its own evidence. A grade for one claim says nothing about the others.
| Claim | What was measured | Evidence |
|---|---|---|
| Reduces all-cause mortality in generally healthy older adults | Lifespan | Against |
Reduces all-cause mortality in generally healthy older adults
Evidence against the claimOutcome measured: Lifespan — Death from any cause was measured.
This is the rare longevity claim that has been directly tested: the D-Health trial randomised over 21,000 older Australians to monthly vitamin D or placebo for five years with death from any cause as the primary outcome. It found no reduction.
Why this grade — the appraisal in full
Well-conducted human research indicates the claimed effect does not occur, or is too small to matter.
- Strongest study design. Randomised controlled trial with 21,315 participants.
- Human research volume. 1 human study, 21,315 participants in total.
- What was measured. 1 human study measured a clinical or functional outcome rather than a laboratory marker alone.
- Replication. The supporting result has not been independently replicated in humans.
- Study duration. Longest human study ran 260 weeks.
Limitations. Participants were mostly vitamin-D replete; the trial does not settle whether correcting genuine deficiency affects mortality. Five years may be too short for some effects.
| Study | Design | Population | Finding |
|---|---|---|---|
| [1]The D-Health Trial: a randomised controlled trial of the effect of vitamin D on …The lancet. Diabetes & endocrinology · 2022 · PMID 35026158 | Randomised controlled trialHuman | 21,315 participantsHealthy participants | Found no effectD-Health: monthly 60,000 IU vitamin D3 vs placebo; no effect on all-cause mortality. |
Human evidence
1 study in people.
- [1]Randomised controlled trial · 21,315 participants
Animal and laboratory evidence
Shown separately, and never used to support a human claim.
No preclinical study is currently linked on this page.
Before anything else
Safety and interactions
Well tolerated at commonly used doses in trials. Very high doses can cause hypercalcaemia. People with kidney disease, sarcoidosis or on certain medicines should seek advice before supplementing.
Practical guidance
If you decide to buy
The purchase case is deficiency correction, not longevity: UK government advice is that everyone consider a small daily dose over autumn and winter, when sunlight is too weak to make vitamin D in skin. Buying it to live longer is the claim the big trials contradicted.
- Which form
- Vitamin D3 (cholecalciferol) — the form used in the major trials and slightly more effective at raising blood levels than D2.
- Typical evidence-aligned dose
- 10 micrograms (400 IU) a day is the UK reference intake; do not exceed 100 micrograms (4,000 IU) a day without medical advice. The mega-doses sold online have no outcome evidence behind them.
- Quality and testing
- Vitamin D is inexpensive and widely tested; any major UK pharmacy own-brand meets the need. A third-party mark (Informed Sport, USP) matters mainly for athletes subject to testing.
- Buying in the UK
- If you suspect actual deficiency (fatigue, bone pain, very limited sun exposure), ask your GP for a blood test rather than self-dosing high — deficiency correction is a medical question with a cheap answer.
Disclosure: Longevity Record is commercially connected to Vitality Supplements. This guidance names no brands, links to no shop, and is written from the trial literature — the grades above were computed before this section was, and no commercial consideration can change them.
The ledger
Grade history
No grade on this page has changed since tracking began. When one moves — a new trial, a retraction, a corrected appraisal — the change is detected automatically and recorded on the public ledger.
Falsifiability
What would change our view
Consistent mortality or healthspan benefits in randomised trials of people who are not deficient — or well-conducted trials in deficient populations showing outcome benefits beyond correcting the deficiency itself.
Check everything
Sources
Every citation links to its PubMed record. Bibliographic details are retrieved from PubMed, not written by us.
- [1]The D-Health Trial: a randomised controlled trial of the effect of vitamin D on mortality Neale RE et al.. The lancet. Diabetes & endocrinology. 2022. PMID 35026158 · doi:10.1016/S2213-8587(21)00345-4