February 2015
Katarzyna Maresz, PhD

 

Abstract

Inadequate calcium intake can lead to decreased bone mineral density, which can increase the risk of bone fractures. Supplemental calcium promotes bone mineral density and strength and can prevent osteoporosis. Recent scientific evidence, however, suggests that elevated consumption of calcium supplements may raise the risk for heart disease and can be connected with accelerated deposit of calcium in blood-vessel walls and soft tissues.

In contrast, vitamin K2 is associated with the inhibition of arterial calcification and arterial stiffening. An adequate intake of vitamin K2 has been shown to lower the risk of vascular damage because it activates matrix GLA protein (MGP), which inhibits the deposits of calcium on the walls. Vitamin K, particularly as vitamin K2, is nearly nonexistent in junk food, with little being consumed even in a healthy Western diet. Vitamin K deficiency results in inadequate activation of MGP, which greatly impairs the process of calcium removal and increases the risk of calcification of the blood vessels. An increased intake of vitamin K2 could be a means of lowering calcium-associated health risks.

Inadequate calcium intake can lead to decreased bone mineral density, which can increase the risk of bone fractures. Supplemental calcium promotes bone mineral density and strength and can prevent osteoporosis (ie, porous bones), particularly in older adults and postmenopausal women.1,2 However, recent scientific evidence suggests that elevated consumption of calcium supplements can raise the risk for heart disease and can be connected to accelerated deposit of calcium in blood vessel walls and soft tissues.3–8

In contrast, vitamin K2 is associated with the inhibition of arterial calcification and arterial stiffening,9,10 which means that increased vitamin K2 intake could be a means of lowering calcium-associated health risks. However, since 1950, the consumption of vitamin K has decreased gradually,11 and even a well-balanced diet might not provide vitamin K in amounts sufficient for satisfying the body’s needs.

Further, due to modern manufacturing processes, the vitamin K content, particularly the vitamin K2 content, of the food supply today has significantly dropped, making vitamin K2 supplements a more reliable way to secure adequate intake.12 By striking the right balance in intake of calcium and K2, it may be possible to fight osteoporosis and simultaneously prevent the calcification and stiffening of the arteries.

A new clinical study with vitamin K2 supplementation showed an improvement in arterial elasticity and regression in age-related arterial stiffening (data pending publication). Most important, through its activation of K–dependent proteins, vitamin K2 can optimize calcium use in the body, preventing any potential negative health impacts associated with increased calcium intake.

 

Vitamin K2: Essential Role

Bone is composed of a hard outer shell and a spongy matrix of inner tissues and is a living substance. The entire skeleton is replaced every 7 to 10 years. During the skeleton’s remodeling, the body releases calcium from the bone into the bloodstream to meet an individual’s metabolic needs, allowing the bone to alter size and shape as it grows or repairs from injuries.13 This remodeling is regulated by osteoblasts—cells that build up the skeleton—and osteoclasts—cells that break down the skeleton. As long as the bone-forming activity (ie, absorption) is greater than the breakdown of bone (ie, resorption), the process of maintaining a healthy bone structure is maintained.

Osteoblasts produce osteocalcin, which helps take calcium from the blood circulation and bind it to the bone matrix. In part, osteocalcin influences bone mineralization through its ability to bind to the mineral component of bone, hydroxyapatite,14 which in turn makes the skeleton stronger and less susceptible to fracture. The newly made osteocalcin, however, is inactive, and it needs vitamin K2 to become fully activated and bind calcium.15

That requirement alone makes vitamin K2 a major player in bone health, but its importance does not stop there. Vitamin K2 also keeps calcium from accumulating in the walls of blood vessels. The vitamin K–dependent protein, matrix GLA protein (MGP), is a central calcification inhibitor produced by the cells of vascular smooth muscles and regulates the potentially fatal accumulation of calcium.16

 

Conclusions

Dietary calcium is linked to many benefits, particularly bone health. Those benefits are why adequate daily intakes for calcium have been established. Because diets often fall short of the guidelines, in particular in individuals with higher needs, such as children, older adults, and postmenopausal women, dietary supplementation can help address the body’s demands. Although the outcomes in studies evaluating high calcium consumption are controversial, some studies do suggest caution when considering supplementation, particularly excessive supplementation, because some evidence points to health problems at elevated levels.3–8

That issue could be remedied, however, if the right amount of vitamin K2 were to be added to a high-calcium regimen. Vitamin K2 promotes arterial flexibility by preventing accumulation of arterial calcium,10,47,62 and supplementation with it could correct calcium amounts in the body that are out of balance. Thus, calcium in tandem with vitamin K2 may well be the solution for bringing necessary bone benefits while circumventing an increased risk for heart disease.