|Hazard Ratios (HRs) vs serum Vitamin D level|
The U curve indicates that a Vitamin D level of greater than 30ng/mL (75nmol/L) increases the Hazard Ratio (HR) for CHD in the top 2.5% of subjects only, relative to 30ng/mL, even though the mean HRs for CHD & all-cause mortality (the more important parameter) are decreasing, up to 66ng/mL. What's occurring?
See Vitamin K. The increase in HR for CHD mortality above 30ng/mL in the top 2.5% of subjects only is almost certainly due to calcification within artery walls, due to under-carboxylation of osteocalcin in bone Matrix Gla Proteins, caused by insufficient Vitamin K2 rather than excessive Vitamin D. This is why I supplement with Vitamin K2. See also Vitamin D toxicity redefined: vitamin K and the molecular mechanism.