physiologic, biochemical, or genetic factors (Combs et al. 2013 ; Hambidge 2003 ).
Discrete functional biomarkers target specific enzymatic pathways, such as the role
of folate status in modifying homocysteine concentrations. Alternatively, general
functional biomarkers target broad-based human response such as the role of vi-
tamin E in modifying oxidative stress of lipoproteins.
Classification of Biomarkers and Relationship to Dietary
Intake
In addition to classifying diet-related biomarkers related to exposure, function, and
susceptibility, the nutrition science community has refined the classification of these
biological indicators according to their role in dietary assessment. There are re-
covery biomarkers, predictive biomarkers, and concentration and replacement
biomarkers. Figure9.3 summarizes the common nutritional biomarkers within each
classification.
Fig. 9.3 Classes of dietary biomarkers measured in biological samples and their application to the
validation of dietary assessment methods, measurement error, and estimation of diet–disease
associations (Jenab et al. 2009 )
180 T.E. Crane and C.A. Thomson