Low-Dose Daily Intake of Vitamin K(2) (Menaquinone-7) Improves Osteocalcin γ-Carboxylation: A Double-Blind, Randomized Controlled Trials

J Nutr Sci Vitaminol (Tokyo). 2015;61(6):471-80. doi: 10.3177/jnsv.61.471.


Vitamin K is essential for bone health, but the effects of low-dose vitamin K intake in Japanese subjects remain unclear. We investigated the effective minimum daily menaquinone-7 dose for improving osteocalcin γ-carboxylation. Study 1 was a double-blind, randomized controlled dose-finding trial; 60 postmenopausal women aged 50-69 y were allocated to one of four dosage group and consumed 0, 50, 100, or 200 μg menaquinone-7 daily for 4 wk, respectively, with a controlled diet in accordance with recommended daily intakes for 2010 in Japan. Study 2 was a double-blind, randomized placebo-controlled trial based on the results of Study 1; 120 subjects aged 20-69 y were allocated to the placebo or MK-7 group and consumed 0 or 100 μg menaquinone-7 daily for 12 wk, respectively. In both studies, circulating carboxylated osteocalcin and undercarboxylated osteocalcin were measured. The carboxylated osteocalcin/undercarboxylated osteocalcin ratio decreased significantly from baseline in the 0 μg menaquinone-7 group, in which subjects consumed the recommended daily intake of vitamin K with vitamin K1 and menaquinone-4 (Study 1). Menaquinone-7 increased the carboxylated osteocalcin/undercarboxylated osteocalcin ratio dose dependently, and significant effects were observed in both the 100 and 200 μg groups compared with the 0 μg group. Undercarboxylated osteocalcin concentrations decreased significantly, and the carboxylated osteocalcin/undercarboxylated osteocalcin ratio increased significantly in the 100 μg menaquinone-7 group compared with the placebo group (Study 2). Daily menaquinone-7 intake ≥100 μg was suggested to improve osteocalcin γ-carboxylation.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Aged
  • Bone and Bones
  • Double-Blind Method
  • Female
  • Humans
  • Japan
  • Male
  • Middle Aged
  • Osteocalcin / blood*
  • Osteoporosis / blood*
  • Osteoporosis / prevention & control
  • Vitamin K 2 / administration & dosage
  • Vitamin K 2 / analogs & derivatives*
  • Vitamin K 2 / pharmacology
  • Vitamin K 2 / therapeutic use
  • Vitamins / administration & dosage
  • Vitamins / pharmacology*
  • Vitamins / therapeutic use
  • Young Adult


  • Vitamins
  • Osteocalcin
  • Vitamin K 2
  • menaquinone 7