Summary: If you are taking coumadin, you may be at risk of heart disease because of vitamin K deficiency. This risk can be reduced by supplementing with certain forms of vitamin K, without adversely affecting your clotting risk. Only change your medication dose under the supervision of your doctor.
Older style blood thinning drugs such as coumadin worked by blocking vitamin K, a co-factor in blood clotting. This has mistakenly caused some people to think that vitamin K causes blood clotting. Doctors frequently advise patients on these medications to avoid leafy green vegetables, such as kale and collards, because of their vitamin K content. This outdated advice is based on poor understanding of vitamin K, and it’s many functions outside of blood clotting.
For someone at risk of blood clots, coumadin can be a life-saving medication, but these types of drugs can also be dangerous, and the dosage must be carefully monitored. Too much can be dangerous, and too little will be ineffective.
But the long-term side effect of these medications is arterial calcification, and calcification of other soft tissues. Why? Because vitamin K is not just a clotting vitamin, it’s a family of many vitamins that are co-factors in both clotting and anti-clotting enzymes, and many enzymes that regulate calcium metabolism, including matrix gla protein, which keeps calcium from precipitating in soft tissue. Using a drug to induce a deficiency in all of the K vitamins has makes matrix gla protein ineffective, and allows calcium to deposit in soft tissues.
The clotting factors are primarily activated in the liver using vitamin K1. The other enzymes that are dependent on the K vitamins, such as matrix gla protein, work in other tissues, and primarily uses vitamin K2 for its function. Vitamin K2 is much more difficult to obtain in our diet, and is more easily depleted. The intake of vitamin K2 has been associated with lower rates of heart disease, and many other chronic health conditions. So if someone needs to take coumadin, why not take a supplement of K2 to prevent the negative effects on our arteries? Recent research has shown that this might indeed help to prevent artery calcification, without having a significant affect on clotting factors.