The bone-heart connection: the health benefits of Vitamin K2.

As we age, there are a couple of pathologies that start becoming more prevalent – Frailty and heart disease.

Our bones become thinner and weaker due to a lack of calcium and this leads to osteoporosis and makes us more susceptible to fractures.

Coronary artery disease also becomes significantly more prevalent and is characterised by increased calcification in the walls of our coronary arteries.

This is interesting because the osteoporosis is characterised by a lack of calcium and coronary disease, characterised by too much calcium and both pathologies are often found in the same patients.

To prevent osteoporosis, many patients take calcium supplements. This is even when body calcium levels are not reduced. However recent research suggests that calcium supplementation could actually increase the risk of coronary artery disease. In a recent publication, researchers conducted a systemic meta-analysis of 13 double blind placebo controlled randomised control trials and found that a dietary calcium intake of 700-1000mg per day or supplementary calcium intake of 1000mg per day significantly increased the risk of coronary heart disease.

Even more interestingly, a recent meta-analysis found that calcium and/or vitamin D supplementation did not seem to reduce fracture incidence in community-dwelling older adults anyway.

So this is all very interesting. Could it be that as we get older, the calcium which is meant to get deposited in our bones, gets deposited in our coronary arteries instead? Could this therefore be the reason why increasing calcium intake does nothing for our bones but actually increases heart disease?

Since these observations,a lot of interest has focussed on Vitamin K and in particular a sub-type of vitamin K called Vitamin K2. Vitamin K2 is a fat soluble vitamin and helps activate osteocalcin which helps take calcium out of the blood and deposits in the bone. So if there is a shortage of vitamin K2, the calcium does not bind to the bone and therefore the bones get thinner.

In the tissues especially in the smooth muscle cells, there exist proteins called matrix GLA proteins and they have the function of removing calcium from the tissues but to do so they need to be activated by Vitamin K2 and vitamin D. So if there is a shortage of vitamin K2, these matrix GLA proteins do not get activated and therefore become non-functional and calcium does not get removed from the blood vessels and therefore get accumulated there and cause heart artery narrowings.

Interestingly there was a study in the journal of vascular research in 2008 that the amount of non-functional matrix GLA protein (I.e that which had not been activated by vitamin K2) was directly correlated with the magnitude of vascular calcification. The more non-functional matrix GLA protein concentrations, the higher the likelihood of vascular calcification.

So is there any evidence that making a concerted effort to increase vitamin K2 can be helpful?
Well – yes – there have been several studies that have confirmed this.

The Rotterdam study took unto 5000 men and women above the age of 55 and followed them up for 8-11 years and found that diets rich in Vitamin K2 were associated with a 50% reduction in arterial calcification and cardiovascular death. In fact mortality from all causes was reduced by 25%!

Another study, known as the PROSPECT study looked at dietary K2 levels and coronary disease in 16000 women and found that with each additional 10mcg/day of K2 supplementation, there was a 9% reduction in cardiovascular mortality.

In 2015, there was another really another very interesting study known as the knapen study which showed that increased Vitamin K2 levels (doses of 180mcg day) resulted in reversal of coronary artery calcification and restore arterial flexibility.