Diet, nutrition, and cancer: past, present and future

Substantial experimental evidence indicates the potential importance of dietary and nutritional factors in cancer prevention, but identifying relationships between diet and cancer in observational epidemiological studies and intervention trials has proved challengingStudy design issues, imprecise dietary assessments, and a lack of consideration of tumour heterogeneity generally attenuate relative-risk estimates in observational studies; dietary biomarkers and characterization of aetiological subtypes can help to better identify diet–cancer associationsInterventional findings are constrained by the timing and brevity of intervention, nonlinear diet–cancer relationships, issues relating to baseline nutritional status, and magnitudes of change in diet that are generally insufficient to affect cancer outcomesFoods and eating patterns are complex, and assessment of dietary patterns, rather than the traditional reductionist approach focused on specific dietary factors, is a new and more-promising strategy for investigating relationships with cancerNew technologies and advances in genetics, epigenetics and metabolomics, and consideration of the influence of the microbiome, will expand our understanding of the role of dietary factors in cancer risk and disease progressionEffectively communicating the status of the evolving science, and evidence-based dietary recommendations for cancer prevention that are based on rigorous review processes should be emphasized in guidance for the public and individual patients