The effect of menaquinone-7 (vitamin K2) supplementation on osteocalcin carboxylation in healthy prepubertal children

Randomized placebo-controlled study in healthy prepubertal children aged 6 to 10 years recruited from primary schools around Utrecht, the Netherlands. The MK-7 arm included 28 participants.

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. The comparison arm received placebo.

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.

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. The study was limited to healthy children from one Dutch region, and habitual vitamin K intake was not collected, which limits generalizability and diet-related interpretation.