Polyphenols are the most abundant
antioxidants in the human diet and are widespread constituents of fruits and beverages, such as
tea,
coffee, and wine. Epidemiological, clinical, and animal studies support a role of
polyphenols in the prevention of various
chronic diseases. For a long time, their direct
antioxidant effect has been reported as the mechanism responsible for the observed health properties. However, recent findings revealed that
polyphenols could interact with cellular signaling cascades regulating the activity of
transcription factors and consequently affecting the expression of genes. Together with this classical regulatory pathway,
polyphenols have been shown to affect the expression of
microRNAs (
miRNA).
miRNAs are small, noncoding RNAs implicated in the regulation of gene expression that control both physiological and
pathological processes such as development and
cancer. Furthermore, expression of
miRNAs can be affected by different external stimuli including nutrients such as
vitamins,
lipids, and
phytochemicals. In this paper, we review studies assessing modulation of
miRNAs expression by dietary
polyphenols that could constitute a new pathway by which these compounds may exert their health effects. Over 100
miRNAs, involved in the control of different cellular processes such as
inflammation or apoptosis, were identified as modulated by
polyphenols. Most of the studies were performed in vitro using different cell lines, particularly
cancer cell lines, and few studies were performed in animals. From all these data,
miRNAs appear as interesting mediators in regulating
polyphenols'
biological effects; however, further studies are needed to validate
miRNA targets and particularly in physiologically relevant conditions taking into account the bioavailability of dietary
polyphenols.