Vitamin D is technically a secosteroid hormone. Its receptor (VDR) is expressed in virtually every nucleated cell in the human body, where it regulates the expression of an estimated 2,000+ genes — approximately 10% of the human genome. The Isle of Man and UK sit at a latitude (50–60°N) at which UV-B radiation is insufficient to drive cutaneous vitamin D synthesis for approximately 6 months of the year (October to April).
Supplementation Protocol
- 2,000–4,000 IU vitamin D3 daily from October to April in the UK as standard
- Year-round supplementation for dark-skinned individuals, office workers, and those with minimal outdoor time
- Take with the largest meal of the day — fat-soluble; absorption is improved with dietary fat
- Vitamin K2 (MK-7, 100–200 mcg) alongside vitamin D3 — directs calcium into bone and away from arterial walls
- Test 25(OH)D if supplementing at higher doses — target 75–150 nmol/L
vitamin Dimmune healthhormonesdepressionbone healthdeficiency