While no effect was observed on the function of the cells lining the arteries (endothelial cells), results published in the European Journal of Nutrition indicate that cranberry juice may reduce the number of endothelial cells that produce a compound called osteocalcin, which has been linked to hardening of the arteries.
“Although endothelial function remains unaffected, our study demonstrates for the first time a potentially beneficial differential effect of cranberry juice on osteoblastic EPCs [endothelial progenitor cells], which are linked to the development of atherosclerotic lesions,” wrote the researchers, led by the Mayo Clinic’s Amir Lerman, MD.
“This preliminary finding is of particular interest as it might partly explain the proposed beneficial effect of cranberry juice and other polyphenol-rich nutrition on cardiovascular health.”
The study was funded by cranberry giant Ocean Spray and the US National Institutes of Health (NIH).
Cranberries and urinary tract health
The link between cranberries and urinary tract health is well established, and linked to its proanthocyanidin (PAC) content. In 2004 France became the first country to approve a health claim for the North American cranberry (Vaccinium macrocarpon) with at least 36mg of proanthocyanidins (PAC) to “help reduce the adhesion of certain E. coli bacteria to the urinary tract walls”, and subsequently fight urinary tract infections (UTIs).
The new study extends our understanding of cranberries, indicating a role for the little red fruit for heart health.
Dr Lerman and his co-workers recruited 84 people with an average age of 49.5 to participate in their double-blind, randomized, controlled trial. Complete study data was available for 69 participants, they said.
The participants were randomly assigned to receive either two glasses of a placebo beverage or double-strength Ocean Spray light cranberry juice for four months.
Using a technique called peripheral arterial tonometry (EndoPAT) the researchers analyzed the how blood vessels responded to the interventions. Blood samples were also taken for an analysis of markers of EPC and osteocalcin.
Results showed that, while there were no differences between the groups for endothelial function, cranberry juice was associated with a reduction in the expression of osteocalcin by EPCs.
“Theoretically, this dietary intervention could therefore influence the dynamic process of atherosclerosis and might expand knowledge about the healthy effects of polyphenol-rich fruits and vegetables in general,” wrote the researchers.
“Moreover, this finding might be especially interesting in the context of high bone turnover states, especially as green tea polyphenols have been shown to be protective for bone loss in middle-aged female rats and are able to mitigate bone loss induced by inflammation in rats.
“Thus, the effect of cranberry juice on potentially osteogenic EPCs in our study might highlight a possible link between the alterations in the bones and vascular calcifications.”
Source: European Journal of Nutrition
Published online ahead of print, doi: 10.1007/s00394-012-0334-4
“Polyphenol-rich cranberry juice has a neutral effect on endothelial function but decreases the fraction of osteocalcin-expressing endothelial progenitor cells”
Authors: A.J. Flammer, E.A. Martin, M. Gossl, R.J. Widmer, R.J. Lennon, J.A. Sexton, D. Loeffler, S. Khosla, L.O. Lerman, A. Lerman