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Oxidative Medicine and Cellular Longevity
Volume 2015 (2015), Article ID 732302, 14 pages
http://dx.doi.org/10.1155/2015/732302
Review Article

Biomarkers of Dietary Polyphenols in Cancer Studies: Current Evidence and Beyond

Department of Environmental Health Science, College of Public Health, University of Georgia, Athens, GA 30602, USA

Received 26 September 2014; Accepted 6 January 2015

Academic Editor: Tullia Maraldi

Copyright © 2015 Jincheng Wang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Polyphenols, commonly contained in fruits and vegetables, have long been associated with a protective role against multiple diseases and adverse health effects. Generally, in vitro and animal experiments have provided strong positive evidence, whereas evidence from in vivo and human epidemiological studies is not strong enough. Most epidemiological studies to date use food frequency questionnaire based dietary intake estimations, which inevitably incur imprecision. Biomarkers of polyphenol have the potential to complement and enhance current studies. This review performed a literature search of all epidemiological studies or controlled clinical/intervention trials which employed biomarkers of exposure for polyphenols to help assess their anticarcinogenic role, using studies on green tea polyphenols as a study model. Currently, studies on this topic are still limited; breast cancer and prostate cancer were the only widely studied cancer types. Isoflavone is the only widely studied polyphenol. In addition to associations between polyphenols and cancer risks, factors such as host genetic susceptibility, epigenetic modification, and gut microbiome patterns may also impact on the protective roles of polyphenols. More evidence should be collected by utilizing biomarkers of exposure for polyphenols in future epidemiological studies before a clear conclusion can be made.