The effect of menaquinone-7 (vitamin K2) supplementation on osteocalcin carboxylation in healthy prepubertal children
What this study found
Eight weeks of MK-7 supplementation improved vitamin K status and osteocalcin carboxylation in healthy prepubertal children, without affecting coagulation parameters. Within the MK-7 group, undercarboxylated osteocalcin and the ucOC:cOC ratio decreased significantly, circulating MK-7 increased significantly, and carboxylated osteocalcin increased slightly but did not clearly reach significance. Between-group differences in percent change for ucOC, UCR, and MK-7 were significantly different from placebo. No adverse events were reported.
- Study & population
- Randomized placebo-controlled study in healthy prepubertal children aged 6 to 10 years recruited from primary schools around Utrecht, the Netherlands.
- Intervention
- Participants in the active arm received one oral capsule daily for 8 weeks containing 45 mg menaquinone-7 (MK-7, vitamin K2) with linseed oil (210 mg) in the capsule.
- Key limitation
- The active arm was small (N=28) and follow-up was short at 8 weeks, so long-term effects on bone mass and fracture risk were not assessed.
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Open PDFOriginal abstract
Vitamin K contributes to bone health, probably through its role as cofactor in the carboxylation of osteocalcin. Intervention studies in adults have demonstrated that markedly higher osteocalcin carboxylation is obtained by intakes of vitamin K well above the current recommended dietary intake. However, the relationship between increased vitamin K2 intake and enhanced osteocalcin carboxylation has never been shown in healthy children. The objective was to study the effect of 45 μg menaquinone-7 (MK-7; one of the vitamin K2 species) on the circulating levels of undercarboxylated osteocalcin (ucOC) and carboxylated osteocalcin (cOC) in healthy prepubertal children. We hypothesised that MK-7 supplementation will reduce the ucOC:cOC ratio (UCR), indicating an improved vitamin K status. The present study is a double-blind randomised placebo-controlled trial examining the effect of 8 weeks MK-7 supplementation on the carboxylation of osteocalcin in healthy children (n 55). Serum levels of ucOC, cOC and MK-7 were measured at baseline and after 8 weeks, together with bone markers and coagulation parameters. The UCR was used as an indicator of vitamin K status. In the MK-7-supplemented group (n 28), the circulating concentration of inactive ucOC reduced and the UCR improved whereas the concentration of MK-7 increased. Within the placebo group, ucOC, cOC, UCR and MK-7 did not significantly change over time. In both groups, bone markers and coagulation parameters remained constant over time. These findings demonstrate that in healthy, prepubertal children, modest supplementation with MK-7 increases circulating concentrations of MK-7 and increases osteocalcin carboxylation.