Longevity Evidence Lab Human evidence, uncertainty intact
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Vitamin and deficiency correction

Vitamin D

Important when deficient; extra supplementation is not a universal longevity multiplier.

The 30-second verdict Vitamin D has established roles in calcium physiology and bone health, and correcting deficiency is clinically important. Large prevention trials and meta-analyses do not support the idea that progressively higher doses broadly prevent cardiovascular disease, cancer or ageing in already replete adults.

Evidence matrix

These scores describe different evidence domains. A strong mechanism cannot compensate for missing human outcomes, and a useful clinical effect need not imply slower biological ageing.

Human clinical outcomes Strong
Human biomarkers Strong
Animal lifespan Preliminary
Mechanistic plausibility Strong
Safety certainty Strong
Direct longevity relevance Limited

What has been shown in humans?

Benefit depends strongly on baseline status, age, setting and endpoint. Bone-related benefit is most relevant in deficient or high-risk groups and often involves calcium, falls prevention or institutional populations. Mortality findings vary across analyses and should not be reduced to a single headline.

What remains uncertain?

The optimal target concentration for every population, who benefits from routine testing, and the balance between population supplementation and targeted correction remain debated.

Doses used in research

Descriptive, not prescriptive Trials range from modest daily dosing to large intermittent boluses. Bolus regimens cannot be assumed equivalent to steady daily intake and have sometimes produced worse fall outcomes.

Safety and interpretation

  • Excessive intake can cause hypercalcaemia, kidney stones and tissue calcification.
  • Blood level, diet, sun exposure, kidney function and medicines can all affect dosing decisions.
  • More is not necessarily better once deficiency has been corrected.

Primary sources and evidence reviews

Editorial note

This dossier was last reviewed on 13 July 2026. Ratings can change when larger trials, adverse-event data or better systematic reviews appear. Corrections should alter the page rather than being buried in a social-media thread.