Response to “Effects of Vitamin K intake on gamma-carboxylated proteins, bone fractures, and vascular calcifications”

Excerpt

We would like to thank Maria Fusaro and colleagues for their suggestion that habitual intake of natto may have a beneficial effect on vascular health, as well as bone health, via vitamin K-dependent matrix Gla protein (MGP), a potent inhibitor of arterial calcification [1]. This is interesting because we know that MGP may be carboxylated only in the presence of vitamin K₂, which is enriched in natto [2]. A systematic review of the relationship between vitamin K and coronary heart disease (CHD) showed no association between vitamin K₁ intake and the incidence of CHD, whereas increased intake of vitamin K₂ is associated with fewer CHD events [3]. Thus, vitamin K₂ may be a more important factor in the prevention of CHD than vitamin K₁. In addition, a usual portion size of natto (50 g) contains approximately 380 μg of vitamin K₂ (menaquinone-7) [4], while the mean vitamin K₂ intake in the cohort studies cited by Rees et al. [3] was only 30 μg/day, with a maximum intake of 128 μg/day [5, 6]. A Japanese population consuming natto would have a higher dietary vitamin K₂ intake than other populations. …