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