Association between Circulating Osteocalcin and Cardiometabolic Risk Factors following a 4-Week Leafy Green Vitamin K-Rich Diet

Background: Evidence suggests that lower serum undercarboxylated osteocalcin (ucOC) may be negatively associated with cardiometabolic health. We investigated whether individuals with a suppression of ucOC following an increase in dietary vitamin K1 exhibit a relative worsening of cardiometabolic risk factors. Materials and Methods: Men (n = 20) and women (n = 10) aged 62 ± 10 years participated in a randomized, controlled, crossover study. The primary analysis involved using data obtained from participants following a high vitamin K1 diet (HK; 4-week intervention of increased leafy green vegetable intake). High and low responders were defined based on the median percent reduction (30%) in ucOC following the HK diet. Blood pressure (resting and 24 h), arterial stiffness, plasma glucose, lipid concentrations, and serum OC forms were assessed. Results: Following the HK diet, ucOC and ucOC/tOC were suppressed more (p < 0.01) in high responders (41 and 29%) versus low responders (12 and 10%). The reduction in ucOC and ucOC/tOC was not associated with changes in blood pressure, arterial stiffness, plasma glucose, or lipid concentrations in the high responders (p > 0.05). Discussion/Conclusion: Suppression of ucOC via consumption of leafy green vegetables has no negative effects on cardiometabolic health, perhaps, in part, because of cross-talk mechanisms.