Effect of Vitamin K Supplementation on Circulating Levels of Osteocalcin on the Bone Metabolism and Aging

Background: OC, also known as bone-Gla-protein (BGP), is the main non-collagen protein of the extracellular matrix in mineralized tissues. It is synthesized by osteoblasts, odontoblasts, and hypertrophic chondrocytes and, through its negative charges, binds calcium and regulates the formation of hydroxyapatite crystals. In humans, circulating OC levels negatively correlate with fasting blood glucose and insulin, Homeostatic Model Assessment for Insulin Resistance (HOMA-IR), body mass index (BMI), hyperlipidemia, and circulating concentrations of leptin. Weight loss (resulting from diet and / or physical activity) improves metabolic profile and muscle strength and increases OC levels. It's interesting to note that high plasma levels of vitamin K or dietary supplementation (MK-7, the natural derivative of vitamin K2), correlate with a reduction in the loss of bone mass and quality. In addition, short-term (1 week) and long-term (3 years) vitamin K supplementation improves insulin resistance in both young and old males and high vitamin K consumption is associated with reduced insulin resistance and reduced risk of developing type 2 mellitus diabetes. Recently, it has been reported in mice that the combination of teriparatide (TPT) and vitamin K is more effective than ionotherapy in improving bone formation, bone density and strength, and in inhibiting bone resorption. Given the putative relevance of the decarboxylated form of OC, GluOC, in the endocrine interaction between bone and organs responsible for the management of energy resources (e.g. endocrine pancreas, skeletal muscle and adipose tissue) whose function is deregulated in elderly subjects and in the syndrome of fragility, this study aims to define a role of supplementation with vitamin K in osteoporosis, another condition characterizing the frailty of the elderly, on the endocrine function of bone tissue and the consequent effects on energy metabolism. There is various evidence regarding the usefulness of using the decarboxylated form of OC as a biomarker for monitoring the response to anti-osteoporotic treatments. In particular, the circulating levels of GluOC respond both to osteometabolic treatments (teriparatide) and to supplementation with vitamin K, in a more relevant way than to total osteocalcin. Study design and treatment: The study includes the following phases: 1. enrollment of controls, after obtaining informed consent. 2. enrollment of patients, after obtaining informed consent. 3. randomization for the patient group 4. prescription teriparatide +/- Vitamin K depending on the group to which it belongs 5. re-evaluation of patients after 6, 12 and 18 months of treatment The group of patients randomized to the teriparatide + Vitamin K / Menaquinone MK-7 arm will have to take MK-7 at a dose of 375 microg / day. Randomization: Patients with osteoporosis will be randomized 1: 1 to one of two treatment groups: * Teriparatide + Vitamin K * Teriparatide The randomization list will be generated with SAS 9.4 software (SAS Institute Inc., Cary, USA) and foresees the presence of blocks. Statistical Analysis: The analysis of the covariance will be performed to evaluate the effect of treatment with and without vitamin K / MK-7 on the primary endpoint measured at 18 months, adjusting for its baseline value (α = 0.05, two-tailed test). The results will also be described in terms of means and 95% confidence intervals both of the absolute values of GluOC at 18 months and of its variations from baseline. This approach will also be followed for the evaluation of the effect of the intake of vitamin K / MK-7 on the secondary endpoints defined by the OC isoforms. The association between GluOC and Gla-type Osteocalcin (GlaOC) levels at 18 months (and changes from baseline) with respect to the markers of energy, bone and muscle metabolism measured at 18 months will also be explored through a linear regression model.