Vitamins K and D

A Power Duo for Health

Vitamins K and D may not be the most glamorous of supplements, but they are two of the most important when it comes to supporting overall health, particularly bone and cardiovascular health. They share a unique (and significant) partnership and are a must in everyone’s daily supplement routine.

Vitamins K and D are fat-soluble vitamins, meaning they dissolve in fat and are stored in the liver and fatty tissue (other fat-soluble vitamins include A and E). Most of us do not get an adequate supply of these vitamins from food, thus it is important to supplement. Vitamins K and D each have their primary functions in the body – blood clotting and regulating calcium levels in the body, respectively – however, at optimal levels, these vitamins go far beyond these basic functions, and together, they are a power duo for bone and cardiovascular health. In fact, one shouldn’t be taken without the other.

Vitamins D and K, the basics

By now, most of us have become familiar with vitamin D and its far-reaching effects on health. At minimal levels, vitamin D is necessary for the bones to absorb calcium. But at optimal levels (50 ng/mL or higher), vitamin D influences thousands of genes, including genes that promote or prevent disease. A number of studies have correlated low vitamin D levels to a plethora of chronic diseases, including cancer, autoimmune diseases, infectious diseases, and cardiovascular disease.[1]

For most people, blood clotting comes to mind when they think of vitamin K. This is, in fact, vitamin K’s basic function in the human body. However, at optimal levels (which most people are lacking), vitamin K plays a large role in human health. And as research about this vitamin continues to grow, its turning out that vitamin K may be just as important to overall health as vitamin D. There are two main forms of vitamin K – K1 and K2 (some researchers insist that these are not simply two forms of the same vitamin, but rather two entirely different vitamins because their effects on health are so different).[2],[3] K1 is found in leafy green vegetables and is the key player in maintaining healthy blood clotting. K2 is found in animal-based foods and natto (a Japanese food made from fermented soybeans), and its role extends beyond blood clotting, influencing heart health, bone health, brain health, and possibly protecting us from cancer.[4] (There are several forms of K2, but for the purpose of this article, we will focus on K2.)

According to vitamin K researcher Kate Rheaume-Bleue, ND an important function of K2 is to activate proteins that control cell growth, meaning that K2 plays a role in cancer protection. “When we’re lacking K2, we’re at much greater risk for osteoporosis, heart disease, and cancer,” Rheaume-Bleue says. She also estimates that about 80 percent of Americans do not get enough vitamin K2 in their diet to activate their K2 proteins, which is similar to the deficiency rate of vitamin D. Although animals can convert vitamin K1 to K2, a significant amount of evidence suggests that humans require preformed K2 in the diet to obtain and maintain optimal health.[5]

Power duo

We know that nutrients do not work alone, but depend on a complex interplay with other nutrients to support physiological processes. Nutrients complement each other, and vitamins D and K are no different. In fact, these two vitamins seem to have an especially important “working” relationship, particularly when it comes to bone health and cardiovascular health.

It has long been known that vitamin D helps the body absorb calcium; however, it wasn’t until more recently that researchers discovered that vitamin K2 is necessary to direct calcium into the bones where it belongs and away from soft tissues, including the arteries.[6] [7] K2 does this by activating a protein hormone called osteocalcin that is needed to bind calcium to the bones and prevent it from depositing in the arteries. Vitamin D and vitamin K also work together to increase matrix GLA protein (MGP), the protein responsible for protecting blood vessels from calcification.[8] Vitamin D is needed to make osteocalcin and MGP, but vitamin K is necessary to activate those proteins to do their jobs.[9] Researchers have postulated that the present recommended daily allowance (RDA) for K is too low to ensure full activation of MGP, putting a large number of people at risk for arterial calcification.[10] This is especially true for those who supplement with calcium and vitamin D but are lacking vitamin K2.

Clinical evidence has shown an association between calcification of the arteries and osteoporosis, suggesting a link between vascular health and bone metabolism.[11] Researchers have also said that one of the most relevant factors in the development in osteoporosis and hypertension (which is often related to arterial calcification) are vitamin D and vitamin K deficiency.[12] It is evident that these two vitamins share a strong working relationship, in both bone metabolism and cardiovascular health, and should be taken as a team so they can do their respective jobs. Rheume-Bleue suggests that for every 1,000 IUs of vitamin D you take, you may benefit from 100 micrograms of K2.[13]

Don’t overlook these two vitamins that are fundamental to health.








[7] Rheaume-Bleue, K. Vitamin K2 and the Calcium Paradox: How a Little Known Vitamin Could Save Your Life. Wiley, 2012.


[9] Rheaume-Bleue, K. Vitamin K2 and the Calcium Paradox: How a Little Known Vitamin Could Save Your Life. Wiley, 2012.




[13] (Interview with Dr. Kate Rheaume-Bleue)