\ curves and U curves: Vitamins D3 and K2 again.

Here are some curves relating to Vitamin D. Ref: http://www.ncbi.nlm.nih.gov/pubmed/23601272

Hazard Ratios (HRs) vs serum Vitamin D level

The solid lines are the 95% confidence intervals (CI) & mean for all-cause mortality. 95% CI's are the values within which 95% of the subjects tested fall. 2.5% fall below the lower CI and 2.5% fall above the upper CI. The dashed lines are the 95% CIs & mean for coronary heart disease (CHD) mortality. Most of the curves follow a \ curve, indicating that more Vitamin D is better, up to 66ng/mL (150nmol/L, the level that I'm at). The interesting curve is the upper dashed line, which follows a U curve.

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 probably 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 ~1mg/day of Vitamin K2. See also Vitamin D toxicity redefined: vitamin K and the molecular mechanism.

Vitamin K

After Vitamin D, Vitamin K will be the "next big thing" you hear about in the media. Why? Just Google "Vitamin K" and see what comes up. At the top of the list is good ol' Wikipedia.

Vitamin K used to be thought of as only the blood clotting vitamin. Some new-borns have to be given Vitamin K injections to ensure proper clotting. However, Vitamin K is needed for the carboxylation of osteocalcin in Bone Matrix Gla Proteins. The what of what in what? In simple terms, Vitamin K is needed to ensure that dietary calcium goes into your bones, rather than into your artery walls, kidneys, brain etc. A lack of Vitamin K can cause osteoporosis. To prevent/treat osteoporosis, either Vitamin K1 (phylloquinone) or Vitamin K2 (menaquinone or menatetrenone) will do. I used 15mg/day K2 (plus Calcium plus Magnesium plus Vitamin D3) to reverse osteoporosis (bone density -2SD) in my lumbar spine.

However, only Vitamin K2 is effective at removing calcium from the media of artery walls. In The Rotterdam Study, "The relative risk (RR) of CHD mortality was reduced in the upper tertile of dietary menaquinone (K2) compared to the lower tertile (RR 0.43, 95% CI: 0.24, 0.77). Phylloquinone (K1) intake was not related to any of the outcomes." An RR of 0.43 means, on average, a 57% reduction in heart attack deaths. I've now put K2 in Cholesterol & Coronary Heart Disease.

Vitamin K2 is required for brain health. See Look after your brain.

See also Vitamin K₂ prevents hyperglycemia and cancellous osteopenia in rats with streptozotocin-induced type 1 diabetes and Vitamins D and K as Pleiotropic Nutrients.

Good food sources of Vitamin K2 can be found here.

Warfarin antagonises Vitamin K, so it can result in arterial calcification. Anyone taking warfarin should ask their GP for regular check-ups to keep an eye on this potential problem.