Bone Abstracts

There is some evidence that caffeine consumption has effects on bone mineral metabolism, however the reports in this regard show some ambiguity. Being this compound one of the most popular for human consumption in the world, we analyzed the effects of soluble caffeine subcutaneous administration on serum osteocalcin and serum bone alkaline phosphatase (bALP) in Wistar male rats (weighting 200–250 g). Variable doses were used (30, 75, 150 mg/kg), during 30 days. The animals were kept in 12:12 h light-dark cycle with controlled temperature (22  °C) and humidity (25%). They were split into four groups (n=4/group): one control and three receiving the treatments with the different doses. The administration was performed 1 h after the light phase started. At the end of the experiment, blood samples were obtained by terminal cardiac puncture under anesthesia. Osteocalcin determination was performed using a specific immunoassay involving monoclonal antibodies, and bone alkaline phosphatase was determined through a heat inactivation kinetic assay. The Institutional Ethics Committee approved this protocol.

The results showed that those animals which received 30 and 75 mg/kg had significant higher levels of osteocalcin (ANOVA, P=0.004 y P=0.016, respectively) compared to those receiving 0 and 150 mg. Regarding bALP, those animals which did not receive caffeine (0 mg/kg) had increased levels of the enzyme (P=0.015) overall. These observations support the notion that caffeine may modulate bone remodeling depending on the dose. Prospective studies are necessary to better understand the significance of our results and the differences in effects on osteogenic potential when caffeine is administered in vivo.