Association of dietary and biochemical measures of vitamin k with quantitative ultrasound of the heel in men and women

Low vitamin K nutritional status is associated with increased fracture risk but is inconsistently related to bone mineral density (BMD), suggesting that vitamin K may affect components of bone strength not measured by BMD, such as microarchitecture. Quantitative ultrasound (QUS) may assess trabecular orientation, providing information on the mechanical properties of bone and may serve as a potential alternative to BMD for gaining insight to the relation between vitamin K and bone strength. We therefore examined the association of vitamin K nutritional status measured in several different ways with QUS in men and women who participated in the Framingham Osteoporosis Study. From 1996 to 2001, broadband ultrasound attenuation (BUA) and speed of sound (SOS) of the calcaneus (heel) were measured in 583 men and 768 women (mean age 59 years). Vitamin K nutritional status was assessed between 1995 and 1998 by three separate measures: plasma phylloquinone concentration, serum percent undercarboxylated osteocalcin (%ucOC) and dietary vitamin K intake. Multiple linear regression analyses were used to calculate regression coefficients in order to evaluate the associations between both measures of QUS and each measure of vitamin K nutritional status. Regression analyses were conducted separately for subgroups of participants defined by gender, menopause status and current use of estrogen replacement medication. Among the men, plasma phylloquinone concentration was positively associated with both BUA (P