Evidence for the relationship between diet and cancer.

The relationship between diet and cancer has advanced in recent years, but much remains to be understood with respect to diet and dietary components in cancer risk and prevention. Evidence from clinical trial outcomes, epidemiological observations, preclinical models and cell culture systems have all provided clues about the biology of cancer prevention. Sequencing of the human genome has opened the door to an exciting new phase for nutritional science. There are also many advances in our understanding of the control of gene expression in eukaryotic cells that might impact cancer development, including mechanisms regulating chromatin structure and dynamics, epigenetic processes (DNA methylation, histone posttranslational modification), transcription factors, and noncoding RNA and evidence suggests that environmental factors such as diet influence these processes. Unraveling the effects of bioactive food components on genes and their encoded proteins as well as identifying genetic influences on dietary factors is essential for identifying those who will and will not benefit from intervention strategies for cancer prevention. Additional research needs concerning diet and cancer prevention include: identification and validation of cancer biomarkers and markers of dietary exposure; investigation of the exposure/temporal relationship between food component intakes and cancer prevention; examination of possible tissue specificity in response to dietary factors; and examination of interactions among bioactive food components as determinants of response. Other emerging areas that require greater attention include understanding the link between obesity, diet and cancer, the interaction between diet and the microbiome, as well as how bioactive food components modulate inflammatory processes. Importantly, for the future of nutrigenomics, the "omics" (e.g., genomics, epigenomics, transcriptomics, proteomics, metabolomics) approach may provide useful biomarkers of cancer prevention, early disease, or nutritional status, as well as identify potential molecular targets in cancer processes that are modulated by dietary constituents and/or dietary patterns.