Polyphenol-rich cranberry juice has a neutral effect on endothelial function but decreases the fraction of osteocalcin-expressing endothelial progenitor cells
Purpose Cranberry juice (CJ) contains a remarkably high
concentration of polyphenols, considered to be beneficial for cardiovascular and bone health. The current double-blind, randomized study was designed to test whether daily consumption of double-strength Ocean Spray light CJ (2 9 230 ml) over 4 months has beneficial effects on vascular
function and on endothelial progenitor cells (EPCs) carrying the osteoblastic marker osteocalcin in particular.
Methods Atotal of 84 participants (49.5 ± 16.2 years)with
peripheral endothelial dysfunction and cardiovascular risk
factors were enrolled in this double-blind, randomized, controlled trial (69 completed the 4-month protocol32 in the CJ group and 37 in the placebo group, respectively). Vascular responses to reactive hyperemia were measured non-invasively by peripheral arterial tonometry (EndoPAT). Peripheral blood mononuclear cells were stained for EPC markers, as well as osteocalcin, and counted by flow cytometry. Results Baseline characteristics were similar in bothgroups. The effect of CJ on peripheral endothelial function
and on circulating EPC counts (CD34?/CD133?/KDR?)
did not change during the study. A high percentage of
EPCs expressed osteocalcin (59.4 ± 35.7%). CJ, as compared
to placebo, induced a decrease in the fraction of
EPCs expressing osteocalcin (-8.64 ± 48.98 and
19.13 ± 46.11%, respectively, p = 0.019). Systemic levels
of the adhesion marker ICAM correlated significantly with
the number of EPCs expressing osteocalcin.
Conclusions The study demonstrated that long-term
supplementation of polyphenol-rich CJ did not improve
peripheral endothelial function. However, the decrease in
the fraction of osteocalcin? EPCs suggests a potential
beneficial effect of polyphenol-rich CJ.