Ana Rodriguez-Mateos, PhD

Lecturer in Nutrition, Division of Diabetes and Nutritional Sciences
Faculty of Life Sciences and Medicine
King's College, London, UK

image of Dr. Rodriguez-Mateos
Abstract: Cranberries are rich in potentially bioactive (poly)phenols, including proanthocyanins, anthocyanins, flavonols and phenolic acids. A limited number of studies have investigated the absorption, distribution, metabolism and excretion (ADME) of cranberry (poly)phenols in humans. Due to the difficulty and cost of obtaining authentic standards from commercial sources, the existing studies which investigated cranberry-derived phenolic acid metabolites have used either enzymatic treatment with glucuronidase and sulfatase to cleave the glucuronide and sulfate moieties from phase II metabolites, or have used the aglycone counterpart for quantification, which leads to inaccurate results. We have recently investigated the ADME of cranberry (poly)phenols using authentic standards. We found that cranberry (poly)phenols are more bioavailable than previously thought, with a large number of small phenolic and ring fission metabolites present in circulation in micromolar concentrations for at least 24 h post-consumption. Sixty metabolites were identified in plasma and urine, including cinnamic acids, dihydrocinnamic, flavonols, benzoic acids, phenylacetic acids, benzaldehydes, valerolactones, hippuric acids, catechols, and pyrogallols. Most of these metabolites are likely derived from gut microbial metabolism of proanthocyanidins and flavonoids, and to a lower extent from direct absorption of phenolic acids and breakdown of anthocyanins. Inter-individual variability of the plasma and urinary metabolite concentration was broad and dependent on the metabolite. Several of these metabolites were found to correlate with improvements in vascular function in a randomized controlled trial conducted in healthy individuals, including cinnamic acid derivatives, a flavonol glucuronide and a valerolactone sulfate. Our results indicate that cranberry (poly)phenols are bioavailable and gut microbial metabolism likely plays an important role in explaining their health benefits.