Nutritional interactions: credentialing of molecular targets for cancer prevention

Dietary behavior has been identified as one of the most important modifiable determinants of cancer risk. Which personalized modifications are needed remains an area of considerable controversy. Part of this uncertainty may arise from interactions among dietary bioactive compounds and/or food combinations. These interactions may either enhance or negate the response to specific foods. Evidence suggests that the cancer-protective effects of an individual's diet may reflect the combined effects of various vitamins, minerals, and other bioactive components such as flavonoids, isothiocyanates, and/or allium compounds rather than from the effect of a single ingredient. A better understanding of physiologically important interactions is needed to determine the merit of combining foods for maximum efficacy for cancer prevention. Furthermore, the response is complicated, since multiple cellular processes associated with carcinogenesis can be modified simultaneously, including sites such as drug metabolism, DNA repair, cell proliferation, apoptosis, inflammation, differentiation, and angiogenesis. Current evidence suggests that bioactive food components can typically influence more than one process. It is essential to have a better understanding of how the response relates to exposures and credentialing which process is most involved in bringing about a change in tumor incidence and/or tumor behavior. Credentialing is being defined as a determination of which cellular process(es) and which bioactive food components are most important for bringing about a phenotypic change. Additional attention is needed to determine the critical intake of dietary components, their duration, and when they should be provided to optimize the desired physiological response. Further research is also needed on the molecular targets for bioactive components and whether genetic and epigenetic events dictate the direction and magnitude of the response.