Vitamin K deficiency, evaluated with higher serum ucOC, was correlated with poor bone status in women

Background An increase in serum undercarboxylated osteocalcin concentrations suggests vitamin K deficiency. Clinical intervention studies suggested that the vitamin K supplementation might contribute to preventing bone loss in postmenopausal women. Evidence on the relationship between serum undercarboxylated osteocalcin (ucOC) levels and bone parameters of quantitative ultrasound (QUS) is limited. We examined the correlation between serum ucOC concentrations and bone status as measured by QUS among middle-aged and older Japanese men and women. Methods The subjects were community-dwelling men ( n = 358) and women ( n = 503) aged ≥ 40 years in Japan. Heel QUS parameters, including the stiffness index, speed of sound, and broadband ultrasound attenuation, were measured. Serum ucOC concentrations were measured by electrochemiluminescence immunoassay. Grip strength was measured in the dominant hand. Information on alcohol drinking, current smoking, exercise, and menopause in women was collected. Results Serum ucOC concentrations were significantly associated with age in both sexes. Serum ucOC concentrations in men were higher at ≥ 80 years than those in the age groups of 40–49, 50–59, and 60–69 years. Serum ucOC concentrations in women were higher in the age groups of 50–59 and 60–69 years than those at 40–49 years. Partial correlation analysis adjusting for covariates (age, body mass index, grip strength, alcohol drinking, current smoking, and exercise in men; age, body mass index, grip strength, alcohol drinking, current smoking, exercise, and menopause in women) showed that serum ucOC concentrations were negatively significantly correlated with all QUS parameters in women. Serum ucOC concentrations were not correlated with them in men. Conclusions Vitamin K deficiency, evaluated with higher serum ucOC, was correlated with poor bone status in women.