Effect of calcium fortified milk supplementation with or without vitamin K on biochemical markers of bone turnover in premenopausal women

Objective We compared the effect of supplementation with a fortified skimmed milk product (high calcium skim milk) with or without added phylloquinone (vitamin K1) on markers of bone formation and resorption in premenopausal women. Methods Eighty-two women 20 to 35 y of age were randomly allocated to three groups. Two groups received two daily servings of high calcium skim milk (1000 mg/d of extra calcium) with or without added phylloquinone (80 μg/d) for 16 wk, and a third control group received no supplementation. Bone density was assessed at baseline and the bone markers, total osteocalcin, type I N-terminal procollagen peptide, and cross-linked C-telopeptide of type I collagen were measured at baseline and at weeks 2, 12, and 16. Serum phylloquinone and undercarboxylated osteocalcin were measured in the control and vitamin K–supplemented groups at weeks 0 and 16. Results Baseline values for age, body mass index, and bone density did not differ across groups. In vitamin K–supplemented women, mean serum phylloquinone concentrations increased from 0.27 to 0.76 μg/L (P < 0.05) and undercarboxylated osteocalcin concentrations decreased from 9.68 to 4.46 μg/L (P < 0.05) over 16 wk. Plasma cross-linked C-telopeptide of type I collagen, total osteocalcin, and type I N-terminal procollagen peptide levels decreased significantly in both supplemented groups compared with the control group over 16 wk (cross-linked C-telopeptide of type I collagen >30%, total osteocalcin and type I N-terminal procollagen peptide >15%). Conclusion Fortified milk supplementation in premenopausal women reduced bone turnover significantly. Phylloquinone fortification substantially improved vitamin K status but had no demonstrable additive effect on bone turnover in this short-term study.