Expert Consensus Score
Vitamin D
Strong Consensus
out of 5
Based on 182 videos across 5 experts · Updated 2026-03-18
Expert Positions
The Verdict
4 of 5 experts recommend vitamin D supplementation for those with suboptimal levels, though Attia urges caution — arguing that the health benefits attributed to high vitamin D may actually come from the outdoor lifestyle needed to achieve them naturally. Patrick is the strongest advocate, citing a 40% reduction in dementia risk.
Quick Protocol
Dosage
1,000-5,000 IU daily of vitamin D3 depending on baseline levels and body weight. Hyman recommends testing levels and targeting 50-80 ng/mL. Patrick suggests most people need supplementation given widespread deficiency.
Form
Vitamin D3 (cholecalciferol), NOT D2. Hyman specifically recommends D3 with K2 for proper calcium metabolism. Fortified foods often use the less effective D2 form.
Timing
Take with a fat-containing meal for better absorption. Morning or midday preferred — some evidence that evening doses can interfere with melatonin production.
Key Findings
- Vitamin D functions as a steroid hormone, not just a vitamin — it regulates over 1,000 genes involved in immune function, cell growth, and inflammation (Patrick).
- A study of 12,000+ people found vitamin D supplementation was associated with a 40% lower risk of dementia over a decade. After 5 years, 84% of vitamin D users were dementia-free vs 68% of non-users (Patrick).
- Low vitamin D levels correlate with 5 years of accelerated biological aging based on telomere length (Patrick).
- 70-80% of the population may have suboptimal vitamin D levels. Factors: sunscreen use, melanin levels, latitude, age, and body fat all reduce production (Patrick, Hyman).
+ 3 more findings in the full report
Read the Full Vitamin D Report
Expert deep dives, video citations with timestamps, risks, synergies, and detailed protocol.
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