Berry phytochemicals, genomic stability and cancer: Evidence for chemoprotection at several stages in the carcinogenic process

Consumption of a diet high in plant-based foods is associated with a decreased risk of epithelial cell cancers at several sites. Cytoprotectants in fruits and vegetables include vitamins, minerals and numerous micronutrients. While there is little evidence uniquely linking berry consumption with lower cancer risk, berries contain high levels of compounds believed to reduce malignant transformation, including the polyphenol flavonoids and anthocyanins. There is strong and convincing evidence that berry extracts and berry phytochemicals modulate biomarkers of DNA damage and indicators of malignant transformation in vitro and in vivo. Data from numerous cell culture and animal models indicate that berry components such as the anthocyanins are potent anticarcinogenic agents and are protective against genomic instability at several sites in the carcinogenic pathway. Anticarcinogenic mechanisms include modulation of carcinogen activation and detoxification, decreased DNA binding of the carcinogen, inhibition of oxidative DNA damage, alteration in cell signalling and malignant transformation and inhibition of cell invasiveness and metastasis. Exactly which berry constituents are cytoprotective remains uncertain and in the majority of in vitro and in vivo studies the concentration of extract or phytochemical employed is non-nutritional. Evidence for an anticarcinogenic effect in human studies is weak.