K2 and Children’s Health

    It is well understood that children require consistent consumption of vitamins, minerals, EFAs, and other nutrients to ensure healthy development.

    Of particular note, as children are experiencing rapid growth, ensuring they attain peak bone mass, bone mineral density, and bone strength are of paramount importance, along with laying a strong foundation for cardiovascular health, to dramatically lower risk of development of osteoporosis and cardiovascular disease when they are older. Without sufficient daily intake of vitamin K2, however, these diseases will indeed likely loom in their futures—food habits and food sources are depleted of vitamin K2—and without adequate supplementation of K2, our future generations remain high at risk of osteoporotic bone fractures and heart attack.

    While vitamin K1 (phylloquinone) is needed for proper blood coagulation, vitamin K2 (menaquinones) is essential to build and maintain strong bones, as well as to avoid calcium deposits in the arteries, promoting cardiovascular health. Vitamin K2 exists in several forms, the most common ones are the synthetic menaquinone-4 (MK-4) and the natural or synthetic menaquinone-7 (MK-7). Of the two forms of vitamin K2, MK-7 lasts longer in the body than MK-4.

    Vitamin K is an essential co-factor for the activation of many vitamin K-dependent pro­teins for coagulation, osteocalcin for bone health, and matrix Gla protein (MGP) for heart health. This activation is critical for proper, effective, and healthy calcium utilization for all life stages — from childhood into adulthood and our senior years.

    Bone & Heart Support

    Osteocalcin is a vitamin K-dependent protein synthesized by osteoblasts, and is related to bone mineralization. Vitamin K, and particularly K2, may also decrease bone resorption by decreasing prostaglandin E2 synthesis in osteoclasts (cells responsi­ble for the dissolution and absorption of bone). As bone tissue grows and develops most intensely during childhood and adolescence, children have the greatest requirement for active osteocalcin and, therefore, vitamin K2. Ninety percent of peak bone mass is attained by age 18 in girls and age 20 in boys. Once that peak is hit in our mid-20s to early 30s, that is all we will ever have and it inevitably declines. Hence, it is vital we lay the strongest foundation possible for attaining peak bone mass at a younger age, so it can be preserved later in life.

    When it comes to healthy cardiovascular development, clinical observations have revealed there are potential implications of vitamin K-deficient children developing a risk for cardiovascular problems later in life – researchers have ob­served arterial calcification in children as young as five to six years of age. Calcification development in the arterial wall occurs over time, resulting in a progressive stiffening of the arteries. Among the proteins involved in vascular calcium metabolism, the vitamin K-dependent MGP plays an important role as a potent inhibitor of arte­rial calcification.

    The relationship between vitamin K2 and MGP viability is a more recent source of interest for research teams, as evidenced by two newly published studies. In one review study, the authors concluded that K2 has "promising potential" as a tool to prevent vascular calcification, notably in those people with high incidence of calcification and those with vitamin K deficiency. (1)

    Another recent study was the first to investigate the roles of inactive dephospho-uncarboxylated matrix Gla Protein (dp-ucMGP) and total uncarboxylated MGP (t-ucMGP) in areas such as peripheral vascular calcification.(2)   The team found that peripheral vascular calcification (which tends to be pronounced in diabetes patients) is clearly associated with dp-ucMGP. Interestingly, this particular association was independent of other factors including total uncarboxylated MGP. There seems to be a new distinction that when further investigated may yield an even more significant role of vitamin K2.

    Inadequate vitamin K status results in higher levels of undercarboxylated (inactive) MGP, which increases the risk of vascular calcification. In the population-based Rotterdam Study, 4,807 subjects were examined to determine whether dietary intake of vita­min K1 and vitamin K2 were related to aortic calcifica­tion and coronary heart disease (CHD). Results showed that severe aortic calcification and the relative risk of CHD mortality was reduced with vitamin K2, but not with vitamin K1. (3)

    This is critical because vitamin K1 is more widely available in the typical Western diet than is vitamin K2, and one study has shown the marked decline in K2-containing food consumption since 1950. (4) A significant study comparing K2 intake in children in 1950 through the 1990s showed that the mid-century-born children obtained approximately 39 mcg of K2 daily compared to 24 mcg daily in children born in the 1990s. The culprit, according to the authors, seems to be a much heavier reliance on nutrient-depleted fast and packaged foods, compared to the earlier reliance on home-made foods and a higher intake of vegetables. This lower intake of K2, say the authors, may have significant implications for future bone and cardiovascular health in children who consume very little vitamin K2.

    Most Children Lack Sufficient Vitamin K2

    In fact, research has revealed a biomarker for vitamin K deficiency that indicates that children probably need more vitamin K than adults.

    The vitamin K-dependent protein osteocalcin plays an impor­tant role in bone metabolism, and circulating undercarboxylated (inactive) osteocalcin (ucOC) is a marker of vitamin K status in bone. As inadequate dietary vitamin K intake results in the synthesis of ucOC, researchers began examining the ratio of circulating ucOC to circulating carboxylated (active) osteocalcin (cOC).

    In one study, researchers measured ucOC 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. In fact – this demonstrated that children have up to eight to 10 times more inactive osteocalcin in bone than do adults. (5) 

    In another study, the vitamin K status of bone in healthy children was compared with that of adults. In chil­dren, a marked elevation of the ratio of ucOC: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. (6)

    Studies have indeed been performed that show vitamin K2 can positively affect bone mineralization, as well as lower fracture risk. One such study looking at serum percentage of uo-OC in 223 healthy pre-teen girls found that higher vitamin K2 intake was associated with increased bone mineral content as well as in the lumbar spine. (7) Another, more widespread in age (healthy girls aged 3 to 16), examined whether vitamin intake and markers of vitamin K status are related to bone mineral content (BMC), as well as bone resorption over a period of four years. Results showed that better vitamin K status was as­sociated with lower bone resorption. (8)

    In a randomized, placebo-controlled trial in which 45 mcg vitamin K2 as MK-7 (as MenaQ7®) was given to healthy prepubertal children, ucOC and cOC were measured, as well as 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. (9) This study is advantageous in that it serves as a clear starting point for further studies investigating the most effective doses to achieve healthy levels of active osteocalcin in children.

    Because compelling scientific evidence for the health-promoting benefits for vitamin K2 continues to mount, notably for its ability to reduce the risk of coronary heart disease, Europe's International Life Sciences Institute has recommended that vitamin K2 needs to be considered alongside vitamin K1 when evaluation the daily value of vitamin K. (10)

    So, retailers, scan your children's sections and call for your favorite brands to add this vital nutrient: they need to seriously consider adding vitamin K2 to all children's multiples and other relevant dietary supplements and functional foods/beverages.

    About the Author: Christopher Speed, MND, APD, has a Master of Human Nutrition and Dietetics from the University of Sydney, continues his academic work as an Associate Editor of the European Journal of Cancer Prevention, and is an adjunct Lecturer at New York University Nutrition School. He has helped overhaul health and wellness communication platforms of many prominent food, nutrition, and supplement companies to drive brand awareness and category leadership through evidence-based nutritional science and influencer outreach.


    1.  El Asmar MS, et al. Vitamin K Dependent Proteins and the Role of Vitamin K2 in the Modulation of Vascular Calcification: A Review. Oman Medical Journal (2014) Vol. 29, No. 3:172-177

    2.  Liabeuf S, et al. Vascular calcification in patients with type 2 diabetes: the involvement of matrix Gla protein. Cardiovascular Diabetology, 2014, 13:85.

    3.  Geleijnse JM, et al. Dietary intake of menaquinone is associated with a reduced risk of coronary heart disease: the Rotterdam Study. J Nutr. 2004 Nov;134(11):3100-5.

    4. Prynne CJ, et al. Intake and sources of phyllo­quinone (vitamin K(1)) in 4-year-old British children: comparison between 1950 and the 1990s. Public Health Nutr. 2005 Apr;8(2):171-80.

    5. Theuwissen E, et al. Vitamin K status in healthy volunteers. Food Funct. 2014 Feb;5(2):229-34.

    6. van Summeren M, et al. Pronounced eleva­tion of undercarboxylated osteocalcin in healthy children. Pediatr Res. 2007 Mar;61(3):366-70.

    7. O'Connor E, et al.  Serum percentage undercarboxylated osteocalcin, a sensitive measure of vitamin K status, and its relationship to bone health indices in Danish girls. Br J Nutr. 2007 Apr;97(4):661-6.

    8. Kalkwarf HJ, et al. Vitamin K, bone turnover, and bone mass in girls. Am J Clin Nutr. 2004 Oct;80(4):1075-80.

    9. van Summeren MJ, et al.. The effect of menaquinone-7 (vitamin K2) supplementation on osteocalcin carboxylation in healthy prepubertal children. Br J Nutr. 2009 Oct;102(8):1171-8.

    10.  Beulens JW, et al. The role of menaquinones (vitamin K₂) in human health. Br J Nutr. 2013 Oct;110(8):1357-1368.