Vitamin D3 K2 Komplex | Shield: which blood markers matter?

When considering a Vitamin D3 K2 complex (e.g., 'Shield'), the most relevant blood marker is 25-hydroxyvitamin D (25(OH)D), which reflects vitamin D status. A target of 30–50 ng/mL is commonly suggested, though individual factors like sun exposure, BMI, and genetics (e.g., VDR polymorphisms) affect dosing. For vitamin K2 (especially menaquinone-7), there is no routine clinical marker. Researchers use undercarboxylated osteocalcin (ucOC) as a functional indicator of vitamin K activity in bone, and PIVKA-II for hepatic K status, but these are not standard in primary care. Proponents claim K2 directs calcium to bones and teeth, preventing vascular calcification. Clinical evidence is moderate: RCTs show benefits for bone density and arterial stiffness in some populations, but not consistently. Crucially, without measuring 25(OH)D, calcium, and parathyroid hormone (PTH) beforehand, supplementation may be unnecessary. Caution is needed in kidney disease or with anticoagulants (e.g., warfarin). DNA test results (e.g., MTHFR, VDR) from the provided context have limited predictive value for individual D3/K2 needs. In summary: 25(OH)D is the key marker; ucOC and PTH are optional. The evidence that D3+K2 is superior to D3 alone remains mixed.