MicroRNAs (miRNAs) are an abundant class of short noncoding RNAs that are widely expressed in mammalian cells and are important in post-translational gene regulation, including regulation of cell proliferation, apoptosis, and differentiation processes. miRNAs are involved in cancer initiation and progression and their expression patterns serve as phenotypic signatures of different cancers. Recent evidence suggests that dietary components as diverse as folate, retinoids, and curcumin exert cancer-protective effects through modulation of miRNA expression. miRNAs may be useful as biomarkers of cancer prevention or nutritional status, as well as serve as potential molecular targets that are influenced by dietary interventions.