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postmenopausal cancer risk (Prentice et al. 2009 ). The analysis showed that while


uncalibrated, self-reported energy intake was not associated with cancer risk, when


biomarker-derived calibration equations were applied, risk for breast cancer was


increased by 24%, colorectal cancer by 11%, and endometrial cancer by 80%.


These data support the notion that self-report error is likely resulting in an under-


estimation of diet–disease risks in the population and support a call for more broad


application of nutritional biomarkers in nutritional epidemiology and clinical trial


research (Prentice et al. 2009 ).


Dietary Biomarker Defined


“Dietary biomarker”has been defined as a biological or biochemical indicator of


dietary intake/exposure that is measured and/or evaluated as a marker of nutrient or


bioactive response (having a biological effect) to a diet-derived exposure


(Potischman and Freudenheim 2003 ). Most importantly, the measurement of


nutritional biomarkers of host susceptibility to disease risks which can be modified


by diet is central to ascertaining diet–disease associations. Figure9.2depicts the


various methods by which different susceptibility factors (such as genetics and
comorbid conditions) may moderate several of the biological pathways that even-


tually, in a downstream cascade, impact overall health (Combs et al. 2013 ). Of note,


the underlying assumption of nutritional biomarkers is that these measures are


objective and, as such, they markedly improve our ability to evaluate diet–disease


associations by reducing measurement error and bias inherent in self-report


methodology.


Fig. 9.2 Susceptibility factors that will moderate characteristics that eventually impact health via
several pathways. Susceptibility factors are like a seesaw or scale between early biological effect
and dietary exposure


9 Biomarkers of Diet and Nutritional Health 177

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