Vitamin K is a term that encompasses several K vitamers or structurally related compounds for similar cofactor activity.
Vitamin K2 (or menaquinones) has two well known forms: MK-4, which has been used in many studies relating to osteoporosis and rheumatoid arthritis and MK-7, which is rising in popularity for it’s applications to both bone and heart health. MK-7 can be from natto and synthesised in the body from bacteria.
It would appear that MK-4 requires a greater deal more than MK-7 to reach the same benefits (MK-4 requires 45,000mg, MK-7 only requires 45mg). Mk-4 also requires multiple dosing whereas MK-7 only needs single dosing.
Menaquinone (MK-7) has been studied multiple times with positive results in prevention of coronary heart disease.
A recent study confirms benefits of vitamin K2 supplementation for cardiovascular health in both men and women. The one year placebo controlled randomised trial examined vitaimin K2 MK-7 on vascular health and body composition in 243 healthy men and women with poor vitamin K status. Researchers concluded that one year-supplementation of MK-7 tended to improve vascular health in both men and women, even more so in post-menopausal women.
“Participants maintained arterial flexibility and the stiffness did not increase, where as placebo group became stiffer and less flexible…These results mirror what we have seen in epidemiological studies, whereas populations who consume a lot of dietary vitamin K2 have healthier hearts and more flexible arteries”.
Vitamin K2 is known to be beneficial for women in post-menopausal age to prevent osteoporosis and rheumatoid arthritis. One study found that intake lower than 109mcg per day had a higher risk of bone fractures.
Adequate intake of vitamin K has not yet been set, however Booth and colleagues have suggested that the current level of intake 90mcg per day is not enough to ensure complete gamma carboxylation of osteocalcin.
Gast G, et al (2009) ‘ A high menaquinone intake reduces the incidence of coronary heart disease’ Nutr Meab Cardicasc Dis. 19(7):504-10
Knpaen M, et al. (2015) ‘Long-term use of MK-7 Supplements improves arterial stiffness in healthy postmenopausal women, especially in women having high arterial stiffness’. Thomb Haemost.113(5):1135-44.
Bo Feskanich, D. et al (1999). ‘Vitamin K intake and hip fractures in women: a prospective study’. Am J Clin Nutr 69, 74-79
Okamoto H, et. al. (2007) ‘Anti-arthritis effects of vitamin K(2) (menaquinone-4)—a new potential therapeutic strategy for rheumatoid arthritis.’ FEBS J. 2007;274(17):4588-4594
iii. Booth, S. L. et al. (2003) ‘Vitamin K intake and bone mineral density in women and men’. Am J Clin Nutr.
Booth, S. L. et al. (2003) ‘Dietary phylloquinone depletion and repletion in older women. The Journal of Nutrition’. 133,2565-2569