VITAMIN-K INTAKE AND OSTEOCALCIN LEVELS IN WOMEN WITH AND WITHOUT AORTIC ATHEROSCLEROSIS - A POPULATION-BASED STUDY

Protein-bound gamma-carboxyglutamate (Gla) has been demonstrated in ca lcified atherosclerotic plaques. Vitamin K is required for the formati on of Cia-residues. As the biological activity of Cia-proteins appears to be strictly dependent on the presence of the Cia-residues, vitamin K status may be an important factor in the development and progressio n of atherosclerotic calcifications. We studied the association of vit amin K status, as assessed by nutritional vitamin K intake and the mea surements of two circulating immunoreactive osteocalcin (irOC) fractio ns, with aortic atherosclerosis in a population-based study of 113 pos tmenopausal women. Women with calcified lesions (n = 34) had a 42.9 mu g lower mean age-adjusted dietary vitamin K intake/day (95% C.I. -6.6 to 92.5) than those without calcifications (n = 79). Atherosclerotic women had higher irOC levels with a low affinity for hydroxyapatite (i rOC(free)): age-adjusted difference of 0.32 ng/ml (95% C.I. 0.03 to 0. 61). In addition, the high affinity irOC levels expressed as a percent age (hydroxyapatite binding capacity, HBC) were 5.12% (95% C.I. 1.32 t o 8.92) lower in women with calcifications. Our study indicates that w omen with aortic atherosclerosis have an impaired vitamin K status as reflected by a lower nutritional vitamin K intake, an increased irOC(f ree) level and a reduced HBC level. An impaired vitamin K status in su bjects with atherosclerosis is compatible with the view that vitamin K or Gla-containing proteins are involved in the development of calcifi cation of the vessel wall.