Vitamin K: its little-known role in vascular health

Among the large family of vitamins, the vitamin K group is often overlooked, even though the body needs vitamin K to function properly. It plays an essential role in bone and tissue structure, as well as in blood clotting processes; indeed, the letter ‘K’ comes from the German word ‘Koagulation’. Alongside these functions, recent studies published in the prestigious journals American Journal of Hypertension¹ and Nephron² show that the K group of vitamins may benefit vascular health, exerting a positive effect against vascular disorders. Here we shed light on this little-known function of vitamin K.

The importance of vitamin K for the cardiovascular system

Numerous proteins in the body depend on vitamin K

Many of the body’s proteins need vitamin K in order to function properly. Some are actually considered to be dependent on the vitamin, as outlined in a 2012 article in the journal Advances in Nutrition³. Present in various parts of the body, these vitamin K-dependent proteins participate in several key chemical reactions. Some, for example, are involved in blood coagulation, cell growth and tissue structure. Without vitamin K, they remain inactive and unable to fulfil their role. As activating factors, the K vitamins therefore influence multiple processes within the body.^1,2 Accordingly, the latest studies indicate a beneficial role vitamin K in cardiovascular health.

MGP, a vitamin K-dependent protein which acts on vessel walls

Within the cardiovascular system, there is one vitamin K-dependent protein which is of particular interest to scientists. This molecule is called matrix-gla-protein, or MGP, and it acts more specifically on vessel walls, as outlined in a study published in the journal Néphrologie & Thérapeutique⁴. According to this study, MGP acts as an inhibitor of vascular calcification, a process in which calcium crystals accumulate in the walls of blood vessels, resulting in increased vascular rigidity. This process is involved in tissue ageing but may also have a pathological cause. Over time, increased vascular rigidity can lead to more serious health complications such as the onset of cardiovascular disease.

The importance of vitamin K in combatting vascular calcification

In order to be able to counter vascular calcification, MGP must first, however, be activated by vitamin K. MGP is actually present in plasma as inactive dephosphorylated, uncarboxylated MGP, but in the presence of vitamin K, it is converted via a chemical reaction into its active form. Once activated, MGP is able to bind to calcium ions and inhibit calcium deposition in tissues. Since vitamin K activation of MGP is thus essential for reducing vascular calcification, this suggests that deficiency in vitamin K could increase the risk of both vascular rigidity, and as a consequence, certain cardiovascular problems.

Therapeutic studies on the effects of vitamin K deficiency on the body

The effect of active MGP deficiency in patients with chronic kidney disease

A number of scientific studies have been conducted to better understand the effects of vitamin K deficiency. One recent study published in the journal Nephron² highlighted an association between the presence of inactive MGP and the incidence of vascular calcification in patients with chronic kidney disease. Involving 83 patients, the study set out to establish a scoring system for vascular calcification, based on various parameters such as the presence of calcium lesions in the abdominal aorta, the degree of vascular rigidity, and levels of dephosphorylated, uncarboxylated MGP. Amongst others, researchers also took into account the patient’s age, and stage of diagnosed chronic kidney disease. They observed that the more advanced the disease, the greater the level of inactive MGP in plasma. At the end of the study, they concluded that a correlation exists between inactive MGP levels and vascular calcification; indeed the higher those levels, the greater the degree of vascular calcification. This therefore suggests that deficiency in vitamin K resulting in decreased levels of active MGP could lead to the development of vascular calcification. This could in turn cause vascular rigidity and potentially lead to the onset of cardiovascular problems.

Active MGP deficiency responsible for vascular rigidity in type 2 diabetics

While the aforementioned research focused on patients with chronic kidney disease, another study looked at type 2 diabetics. Given that vascular rigidity is known to increase in type 2 diabetes, the researchers here examined the metabolic pathways involved in this process. The study concentrated on measuring various parameters of vascular rigidity such as pulse wave velocity in the carotid and femoral arteries. In their analysis, the researchers also took into account levels of dephosphorylated, uncarboxylated MGP. Published in the American Journal of Hypertension², the study’s conclusions suggest that a decrease in activation of MGP by vitamin K could be responsible for rigidity of artery walls in type 2 diabetics.

These new findings expand scientific understanding of the many roles played by vitamin K in the body. They add to the considerable number of studies on the subject, reflected in our various articles: Vitamin K and the prevention of fractures, Vitamin K and the risk of diabetes, and Vitamin K and long-term health. These studies are also the basis for the development over recent years of a number of vitamin K-based dietary supplements. For example, it is now possible to buy a supplement that combines three forms of vitamin K (K1, K2 MK-4, K2 MK-7) in one formulation: Complete K

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> Sources :

1. Mayank Sardana et al., Inactive Matrix Gla-Protein and Arterial Stiffness in Type 2 Diabetes Mellitus, Am J Hypertens (2016) hpw146.
2. Thamratnopkoon S.a · Susantitaphong P.a · Tumkosit M.b · Katavetin P.a · Tiranathanagul K.a · Praditpornsilpa K.a · Eiam-Ong S.a , Correlations of Plasma Desphosphorylated Uncarboxylated Matrix Gla Protein with Vascular Calcification and Vascular Stiffness in Chronic Kidney Disease, Nephron, Vol. 135, No. 3, 2017.
3. Theuwissen E1, Smit E, Vermeer C., The role of vitamin K in soft-tissue calcification., Adv Nutr. 2012 Mar 1;3(2):166-73.
4. Pierre Delanaye, Sophie Liabeuf, Antoine Bouquegneau, Étienne Cavalier, Ziad A. Massy, L’éveil de la matrix-gla-protéine sonnera le glas des calcifications vasculaires, Néphrologie & Thérapeutique, Volume 11, n° 4, pages 191-200 (juillet 2015).