Nutritional
epidemiology examines the role of nutrition in the etiology of disease, monitors the nutritional status of populations, develops and evaluates interventions to achieve and maintain healthful eating patterns among populations, and examines the
relationship and synergy between nutrition and
physical activity in
health and disease.Similar to the early studies of nutrition deficiency, associations between dietary factors and chronic disease may be observed long before a specific etiologic
factor can be identified (Jacob, 1999). However, the path from observing to curing disease is more complicated for
chronic diseases than deficiency diseases, because chronic disease etiology is multifactorial and diseases take many years to develop or manifest.Evidence from a variety of study designs is required to establish a definitive
relationship between diet and disease. Basic
biochemistry and physiology, cell culture experiments, laboratory animal studies, and human metabolic studies provide pertinent mechanistic data to implicate a role for a specific dietary
factor in carcinogenesis. However, these studies cannot prove that a particular dietary
factor will cause or prevent a
cancer in humans. Proof can only be established in human studies, preferably through randomized intervention trials. However, such trials are not always feasible. One challenge is the high cost of long-term studies, given that
cancer takes years to develop. In addition, it is ethically implausible to test the
relationship between a potentially harmful exposure and
cancer in humans. For these reasons, the bulk of the available evidence for a particular diet–cancer
relationship is garnered from observational nutritional epidemiological studies. This chapter provides an overview of the
nutritional epidemiology of cancer, with particular emphasis on study design, dietary assessment, and analysis, as well as interpretation of findings.
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