We compared the effect of supplementation with a fortified skimmed milk product (high calcium skim milk) with or without added phylloquinone (vitamin K(1)) on markers of bone formation and resorption in premenopausal women.
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 microg/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.
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 microg/L (P < 0.05) and undercarboxylated osteocalcin concentrations decreased from 9.68 to 4.46 microg/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%).
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.