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Evidence Review
Vitamin D
Verdict
PromisingEvidence Tier
B
Moderate evidence
Human Studies
Yes — large trials
Typical Cost
$5-10/mo
Vitamin D deficiency is clearly harmful. Supplementation in deficient individuals improves bone health and may reduce infection risk. However, the VITAL trial showed that supplementing vitamin D in non-deficient adults did not reduce cancer or cardiovascular events. The lesson: correct deficiency, but megadosing in people with adequate levels is not supported.
The full evidence review — including what the VITAL trial showed about supplementing when you're not actually deficient — is in Section 10 (The Supplement Deep-Dive) of The Anti-Longevity Playbook.
Reviewed by Dr. Ramy Khalil, MD · Double Board-Certified Internal Medicine · Last updated March 2026
Should I take vitamin D for longevity?
Correct deficiency — that's clearly beneficial. But the VITAL trial showed supplementing non-deficient adults didn't reduce cancer or cardiovascular events. Test your levels first.
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