Vitamin K2: Part Two – Artery Calcification
In Vitamin K2: Part One, I reported on a study from EPIC that followed 16,000 women for 8 years and found an arguably borderline statistically significant, beneficial association for vitamin K2 and the prevention of heart disease.
The same group of researchers, from The Netherlands, published another study of 564 post-menopausal women, comparing their vitamin K intakes to coronary artery calcification (1).
The theory is that vitamin K activates proteins that sequester calcium. Vitamin K1 is cleared from the bloodstream for use in the liver while vitamin K2 is much more likely to be found in the vessel walls where it can prevent calcium from being deposited in the vessel walls.
As predicted, the results showed that vitamin K1 was not associated with a reduced amount of coronary artery calcification. Vitamin K2, however, was associated with reduced risk in a borderline statistically significant manner.
In comparing the highest one-fourth of intake to the lowest, in the model adjusted only for age, the risk was barely statistically significant at 0.82 (0.68–0.99).
In the model adjusted further for smoking, diabetes, BMI, hypertension, educational attainment, HDL and LDL cholesterol, the risk was 0.85 (0.72–1.02); not statistically significant.
And in the model adjusted even further for alcohol consumption and energy-adjusted intake of protein, calcium and fiber the risk was back to statistically significant at 0.80 (0.65–0.98).
Interestingly, the women in the highest intake of vitamin K2 also had the highest intake of calcium at 1,317 mg per day, and calcium and vitamin K2 intakes were significantly associated with each other. Ditto for protein (but not fiber).
Why would women with the highest calcium intake have the lowest amount of artery calcification? Well, as I have written about before, dietary calcium does not appear to cause calcification of the arteries until calcium intakes reach at least 1,400 mg per day, if at all (see Calcium Supplements – The Final Word?).
MK4 was the only vitamin K2 subtype that showed an individual trend towards less artery calcification.
People should keep in mind that this study was cross-sectional, making it a less reliable form of evidence than a prospective study (other things being equal).
In summary, vitamin K2 intake was weakly associated with a lower risk for artery calcification.
1. Beulens JW, Bots ML, Atsma F, Bartelink ML, Prokop M, Geleijnse JM, Witteman JC, Grobbee DE, van der Schouw YT. High dietary menaquinone intake is associated with reduced coronary calcification. Atherosclerosis. 2009 Apr;203(2):489-93. | link