Vitamin D3 + K2
The sunshine vitamin — foundational for immune function and bone health
What It Is
Vitamin D deficiency accelerates multiple aging biomarkers. D3 supplementation is one of the most broadly supported interventions, especially for those over 40 or living in northern latitudes. K2 ensures calcium goes to bones, not arteries.
How It Works
Vitamin D3 binds to the VDR receptor in nearly every cell type, modulating ~1,000 genes involved in immune function, inflammation, and cell differentiation. K2 activates Matrix GLA Protein (MGP) which inhibits arterial calcification.
The Science
Vitamin D supplementation and total mortality: a meta-analysis of randomized controlled trials
Archives of Internal Medicine (2007) · PubMed
Meta-analysis of 18 RCTs showing modest reduction in all-cause mortality with D3 supplementation.
Vitamin K2 supplementation and arterial stiffness in postmenopausal women
Thrombosis and Haemostasis (2015) · PubMed
3-year RCT showing MK-7 supplementation improved arterial stiffness, especially in women with high baseline stiffness.
Dosage
1,000–5,000 IU/day D3 is common. Optimal blood level: 40–60 ng/mL (test via blood draw). K2 as MK-7: 100–200 mcg/day.
Safety
Very safe at recommended doses. Toxicity rare below 10,000 IU/day. Always test blood levels before mega-dosing. K2 is important to pair with D3 to prevent calcium misallocation.
Skeptic's Corner
While deficiency clearly harms health, whether supplementing above sufficiency provides additional longevity benefits is less clear. The VITAL trial showed no cancer mortality reduction from D3 supplementation. Test your levels before supplementing.
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