Vitamin K is a fat-soluble vitamin occurring in two forms – K1 and K2. There are multiple subtypes of vitamin K2 including menaquinones. Some studies have shown that vitamin K prevents the calcification and hardening of blood vessels which leads to cardiovascular diseases. This study is the first to examine the role of vitamin K in preventing coronary heart disease. The results suggest that a high intake of vitamin K2 may protect against coronary heart disease in elderly women.
Vitamin K prevents the deposition of calcium in blood vessels, and thereby prevents their hardening, by regulating chemical changes in an amino acid called glutamic acid. The products of this process, such as Matrix-Gla Proteins (MGP), are directly involved in preventing calcium deposition in arteries, Hence, under conditions of vitamin K deficiency, calcium deposition in blood vessels increases, ultimately resulting in coronary heart disease. It has been observed that the levels of Matrix-Gla proteins are low in blood vessels of many seemingly healthy individuals. This indicates that even healthy people have vitamin K deficiency. The study examined the relationship between vitamin K consumption and the risk of cardiovascular disease. It also evaluated which type of vitamin K is most beneficial.
* The study included 16,057 post-menopausal women, who were part of the European Prospective Investigation into Cancer and Nutrition survey conducted between 1993 and 1997.
* The baseline data included demographic characteristics, blood pressure and body mass index. The presence of diabetes and high cholesterol were also noted.
* The amount of vitamin K1 and K2, and different types of vitamin K2, consumed were assessed with the help of a food frequency questionnaire,
* The number of women who were hospitalized, or had died from coronary heart disease, was calculated using data obtained from the Dutch Center for Health Care Information.
* The average vitamin K1 consumption was 211 µgm/day and that of vitamin K2 was 29 µgm/day. Menaquinones were the most common form of vitamin K2 consumed.
* The occurrence of diabetes, high blood pressure and high cholesterol were greater in those who consumed higher quantities of vitamin K1. High consumption of vitamin K2 was associated with an increased prevalence of diabetes, but lesser prevalence of high cholesterol.
* In the eight years of follow-up, 480 women developed coronary heart disease and 32 had died of it.
* A higher consumption of vitamin K2 was associated with low occurrence of coronary heart disease. This beneficial effect was associated with consumption of menaquinones; no association was found with vitamin K1.
The food frequency questionnaire used for estimating the consumption of vitamin K was not properly validated. This study was limited to post-menopausal women. Hence, the findings of this study cannot be generalized. Since the researchers of this study did not have access to patients’ charts, they could not validate the diagnosis of coronary heart disease.
This study shows that the consumption of higher levels of vitamin K2 in the diet reduced the incidence of coronary heart disease. This effect was related mainly to the levels of menaquinones, subtypes of vitamin K2. Major sources of vitamin K2 are cheese, milk and meat. However, in order to increase the consumption of vitamin K2 and thus prevent coronary heart disease, one cannot increase the consumption of foods that are rich in vitamin K2. Being rich in fats, they themselves can predispose an individual to the development of coronary heart disease. Hence, it is necessary to find other sources of vitamin K2 such a low-fat dairy products or supplements.
For More Information:
A High Menaquinone Intake Reduces the Incidence of Coronary Heart Disease
Nutrition, Metabolism and Cardiovascular Diseases, 2009
By G. C. M. Gast; N. M. de Roos, The University Medical Center Utrecht, Utrecht, Netherlands and Wageningen University, Wageningen, Netherlands.