Vitamin D (cholecalciferol / D3)
Immune · Secosteroid hormone
Tier A
What this is
VITAL (2019, n=25,871) largely negative for CV and cancer primary prevention in generally-sufficient Americans — suggests supplementation mostly helps deficient individuals. Jolliffe 2021 respiratory infection meta: modest protective effect. Biohacker obsession with 'higher is better' above 60 ng/mL not well-supported. K2 co-supplementation often promoted with thin evidence.
Mechanism
Ultraviolet-synthesized or dietary D3 → 25-OH-D (storage) → 1,25-(OH)2-D (active); binds VDR (nuclear receptor) throughout body; modulates thousands of genes; immunomodulatory — shifts Th1/Th17 toward Treg
Dose & route
2000-5000 IU/day D3 (aim 25-OH-D 40-60 ng/mL per biohacker consensus; mainstream target 30+)
Citations
- https://pubmed.ncbi.nlm.nih.gov/30415629/
- https://pubmed.ncbi.nlm.nih.gov/33611047/
- https://pmc.ncbi.nlm.nih.gov/articles/PMC6950667/
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This is an independent synthesis of published research by a non-clinician. Scores are opinions supported by citations, not prescriptions. See the full disclaimer and methodology for how this score was produced and what it does and doesn't mean.