Vitamin D3 + K2 for Healthy Ageing

TL;DR: As we age, skin becomes less efficient at producing vitamin D and bone density naturally declines. Maintaining optimal vitamin D and K2 status supports bone strength, reduces fracture risk, and helps direct calcium correctly — critical for independence and quality of life after 65.

Evidence rating: ⭐⭐⭐⭐⭐ Robust

Why Vitamin D3 + K2 Matters for Healthy Ageing

Older adults are at higher risk of vitamin D deficiency due to reduced skin synthesis, less time outdoors, and dietary intake often below requirements. Vitamin D is essential for calcium absorption, while K2 ensures that calcium is directed into bone rather than soft tissue or arteries.

Key Study: Yao, P. et al. (2019). Vitamin D and Calcium for the Prevention of Fracture: A Systematic Review and Meta-analysis. JAMA Network Open, 2(12), e1917789. https://doi.org/10.1001/jamanetworkopen.2019.17789 — confirmed vitamin D supplementation (especially with calcium) significantly reduced fracture risk in older adults.

Supporting evidence: Thompson, B. et al. (2023) D-Health trial (over 21,000 participants at similar southern latitude to NZ) showed vitamin D supplementation reduced major cardiovascular events by 9%. van Ballegooijen, A.J. et al. (2017) highlighted the synergistic role of D3 + K2 in both bone mineralisation and arterial health. Nowson, C.A. et al. (2012) noted higher deficiency risk in older New Zealand adults.

Practical note: Many NZ practitioners recommend 2,000–4,000 IU D3 + 200 mcg K2 daily for adults over 65 during winter months, with regular blood testing to maintain levels between 75–125 nmol/L.

This is not medical advice. BioHackNZ provides general information based on published research. Always consult your healthcare provider before starting any supplement regimen. Individual results vary.

Last updated: 18 May 2026 | BioHackNZ Research Team

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