How They Interact
D3 increases calcium absorption from gut. K2 activates osteocalcin (binds Ca to bone) and MGP (prevents Ca deposition in arteries). Without K2, high-dose D3 theoretically increases vascular calcification risk.
Optimal Ratio
1000 IU D3 : 10-25μg K2 MK-7
Practical Recommendation
Always pair D3 supplements with K2. Food: natto (richest K2 source), aged cheese, egg yolk, chicken liver.