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Research demonstrates that children are the most deficient of the essential nutrient vitamin K2, creating serious skeletal and vascular implications for growing bodies. Fortunately, there is a simple, proven solution: studies have shown that supplementation with 45-50 mcg of vitamin K2 as MK-7 daily supports bone mineral density, reduces fractures, and may contribute toward cardiovascular health in children – laying the strong foundation for their transition from adolescence into adulthood.

Vitamin K is actually a group of fat-soluble vitamins. It was first recognized for its essential role in the functioning of several proteins involved in blood clotting or coagulation, which is important to prevent excessive bleeding after an injury. In fact, the “K” in vitamin K is derived from the German word “koagulation.” Now, vitamin K is understood to offer additional benefits, including its role activating vitamin K-dependent proteins that are necessary for bone mineralization (e.g., helping to keep calcium in the bone) , as well as utilizing calcium for healthy bones.

The two naturally occurring forms of vitamin K are K1 and K2. Plants synthesize phylloquinone, which is also known as vitamin K1. Friendly intestinal bacteria synthesize a range of vitamin K2 forms collectively referred to as menaquinones. The menaquinone form of vitamin K2 is designated according to the number of repeating 5-carbon units in the side chain of the molecule. For example, if there are seven repeating 5-carbon units, the designation will be menaquinone-7, or MK-7. Vitamin K2 appears to offer the greater range of benefits to human health.

It should be noted that vitamin K2 is available for supplementation as MK-7 and MK-4. In research, peak serum concentration has been recorded at 2 hours after supplementation for MK-4 and 4 hours for MK-7 after intake. However, MK-4 quickly disappears from the circulation (after approximately 8 hours), whereas MK-7 is capable of accumulating in the bloodstream (remains in the body for approximately 72 hours). Supplementation with MK-7 only needs to be taken once a day and is therefore more convenient.

Physiological Functions

Vitamin K performs important physiological nutritional functions. These include coagulation, bone mineralization and promoting cardiovascular health (through the inhibition of vascular calcification).

Coagulation (clotting)

Vitamin K-dependent clotting factors, or proteins, are necessary for the coagulation cascade, which is a series of dependent events that stop bleeding through clot formation. Vitamin K-dependent protein Z appears to enhance the action of thrombin and has an anticoagulatory function. Protein C and protein S are also anticoagulant proteins that provide control and balance in the coagulation cascade. Control mechanisms for the coagulation cascade exist because uncontrolled clotting may be as life-threatening as uncontrolled bleeding. Vitamin K-dependent coagulation factors are synthesized in the liver.

Vitamin K has been and is still being given to newborns as a shot immediately after birth because vitamin K is needed for normal blood coagulation and the baby’s vitamin K level is usually very low. In 1894, the American pediatrician Charles Townsend discovered that newborns in very rare occasions showed a tendency to bleeding, but with a different pattern than the typical known bleeding disorders. Nevertheless, such bleeding was serious as the condition could lead to bleeding in the brain (intracranial hemorrhage). Townsend observed that bleeding spontaneously ceased in a 9-day-old infant who received insufficient breast milk and was given formula instead. Thus, the doctor found the link between diet and this type of bleeding. This is because of the multiple coagulation factors must be activated before they can stop the bleeding, and that they are not activated without the presence of vitamin K.

Bone Mineralization

Osteocalcin is a vitamin-K dependent protein that has been isolated in bone. Osteocalcin is a protein synthesized by osteoblasts, and is thought to be related to bone mineralization. Osteocalcin facilitates normal bone growth and development. Vitamin K may also decrease bone resorption by decreasing prostaglandin E2 synthesis in osteoclasts (cells responsible for the dissolution and absorption of bone), and by effects on calcium balance, and interleukin production in bone. In addition, protein S, a vitamin K-dependent anticoagulant protein, is synthesized by osteoblasts. Although its role in bone metabolism is not clear, children with inherited protein S deficiency suffer complications related to increased blood clotting, as well as decreased bone density. As bone tissue grows and develops most intensively during childhood and adolescence, children have the greatest requirement for active osteocalcin and K vitamins.

The higher peak bone mass children achieve, the lower the risk of poor bone health and potentially osteoporosis when they become elderly. Hence, achievement of optimal pubertal vitamin K status is important to prevent disorders in later life.

Research demonstrates that children, in particular, may not be receiving a sufficient intake of vitamin K, which is problematic since a lack of this nutrient poses serious implications for bone growth. Studies have shown that daily supplementation with 45-50 mcg of vitamin K2 supports bone mineral density from early childhood and into adolescence. As a result, K2 helps to reduce fractures at almost any age.

Vitamin K2’s absence of from diets has created a staggering insufficiency – leaving children underprepared to form the foundation of health that will support them into adulthood. For children and adults with the most pronounced K deficiencies, supplementation with vitamin K2 (MK-7) has been shown to evoke the highest response.

Bacteria that normally colonize the large intestine synthesize menaquinones (vitamin K2), which are an active form of vitamin K. Until recently it was thought that up to 50% of the human vitamin K requirement might be met by bacterial synthesis. However, research indicates that the contribution of bacterial synthesis is much less than previously thought, although the exact contribution remains unclear.

In newborn infants, this is exacerbated by the fact that they have not yet developed bacterial colonies in their intestines. Consequently, newborn infants generally have low vitamin K status. For infants in the United States, vitamin K deficiency without bleeding may occur in as many as 50% of infants younger than 5 days old. In addition, the average intake of vitamin K in infants who are exclusively breast-fed during the first 6 months of life has been reported to be less than 1 mcg/day; this is approximately 100-fold lower than the intake in infants fed a typical supplemented formula. This is a good reason for breast-feeding mothers to consider supplementation with vitamin K2.


In another study, researchers measured circulating uncarboxylated (i.e., inactive) osteocalcin (ucOC), a marker of the vitamin K status in bone, in 896 samples of healthy volunteers and vitamin K-deficient target groups.

The response to vitamin K supplements was measured in 42 children and 68 adults. Children had high ucOC levels, reflecting low vitamin K status. Children and adults with more pronounced vitamin K deficiency gave the highest responses to vitamin K2 (MK-7) supplementation. Researchers concluded that children showed the largest tissue-specific vitamin deficiency and, accordingly, may benefit from MK-7 supplementation to improve vitamin K status.

The vitamin K-dependent protein osteocalcin plays an important role in bone metabolism. Inadequate dietary vitamin K intake results in the synthesis of ucOC. In a cross-sectional study, the vitamin K status of bone in healthy children (n = 86) was compared with that of adults (n = 30). In children, a marked elevation of the ratio of ucOC/ carboxylated osteocalcin (cOC), indicative of a poor vitamin K status, was observed. Furthermore, a marked correlation between the bone markers for bone metabolism and ucOC and cOC was found in the children’s group. These findings suggest a pronounced low vitamin K status of bone during growth.

Additionally, individuals with disorders of fat malabsorption may be at increased risk of vitamin K deficiency. Symptoms of deficiency include easy bruising and bleeding. This may occur as nosebleeds, bleeding gums, blood in the urine, blood in the stool, tarry black stools, or extremely heavy menstrual bleeding.

While studies may have begun with adults, research has progressed to examine child populations – both healthy and ill – revealing amazing results. Not only recognizing an intense need, but identifying the most effective solution, K2 (MK-7), as well as dosage.

Bone Mineralization

Various clinical trials in adults have reported that daily supplementation with vitamin K2 daily improved bone mineral density (BMD), significantly reduced bone loss, reduced the risk of fracture, and improved measures of bone strength. In addition, research has also demonstrated the relationship between vitamin K and bone mineralization in children.

A European study investigated the relationship between serum percentage of undercarboxylated osteocalcin (marker of vitamin K status, where higher levels reflect lower vitamin K status), BMD, and biochemical markers of bone turnover in 223 healthy girls aged 11-12 years—a stage of dynamic bone development, which may represent an important window of opportunity for vitamin K status to modulate childhood bone health. Results demonstrated that better vitamin K status was associated with increased BMD of the total body (P < 0.001) and lumbar spine (P < 0.05) in healthy peri-pubertal girls.

Another study with 245 healthy girls aged 3-16 years examined whether vitamin intake and markers of vitamin K status are related to bone mineral content (BMC), as well bone resorption over a period of 4 years. Results showed that better vitamin K status (high plasma vitamin K and low undercarboxylated osteocalcin) was associated with lower bone resorption. In short, better vitamin K status (at least 45 mcg/day) was associated with decreased bone turnover in healthy girls consuming a typical U.S. diet.

A prospective, one-year pilot study investigated the effects of a dietary supplement with vitamin K2 (50 mcg menaquinone-7) and vitamin D (5 mcg calcitriol) on 20 children with thalassemic osteopathy or TOSP (a blood disorder that may result in osteopenia and osteoporosis). Results showed a significant improvement in the BMD at the lumbar spine area of the patients at month 6 and month 12 of the treatment, especially in the prepubertal group. This pilot study demonstrated that vitamin K2 and calcitriol combination clearly has a positive effect on the BMD of the children with TOSP.

Further, researchers conducted an 8-week, doubleblind, randomized, placebo-controlled trial37   in which 45 mcg vitamin K2 (as MenaQ7®) was given to healthy prepubertal children, and undercarboxylated osteocalcin (ucOC) and carboxylated osteocalcin (cOC) were measured, as well as the the ucOC:cOC ratio (UCR) as an indicator of vitamin K status. Results showed that with increases in MK-7, the circulating concentration of inactive ucOC reduced and the UCR improved. There were no significant changes in the placebo group. Researchers concluded that supplementation with MenaQ7® vitamin K2 increases circulating concentrations of MK-7 and increases osteocalcin carboxylation in healthy, prepubertal children.

Supplementation offers a viable option for addressing children’s vitamin K2 deficiencies – leading to significant improvements in bone mineral density and reduced incidence of fractures, as well as putting them on the road to good cardiovascular health.

Researchers concluded that supplementation with MenaQ7® (vitamin K2 )increases circulating concentrations of MK-7 and increases osteocalcin activation.


The incidence of forearm fractures in children peaks around the time of the pubertal growth spurt, possibly because of physical activity increases at the same time that there is less cortical bone mass due to the increased calcium demand during skeletal growth. A population-based study in Minnesota examined whether there has been a change in the incidence of forearm fractures in children in recent years by reviewing data on forearm fractures during 4 time periods: 1969-1971, 1979-1981, 1989-1991, and 1999-2001. The results showed that annual incidence rates of forearm fractures per 100,000 increased from 263.3 in 1969-1971 to 322.3 in 1979-1981, and to 399.8 in 1989-1991 before leveling off at 372.9 in 1999-2001. Age-adjusted incidence rates per 100,000 were 32% greater among male residents in 1999-2001 compared with 1969-1971 (P =0.01), and 56% greater among female residents in the same time periods (P < 0.001).

In comparing the previous data on the decreased intake of vitamin K from the 1950s to the 1990s (a 40-year period) with the data from the Minnesota study showing an increase in forearm fractures over a similar 30-year period, it is interesting to note the graphic correlation between the two sets of data; namely, as vitamin K intake in children decreased, forearm fractures in children increased.

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