It is well known that diet is a modiable risk factor for chronic disease; however, epidemiologic studies do not consistently support associations between specic foods or nutrients and disease end points. Most epidemiologic studies rely on self-reported dietary assessment methods that are subject to recall bias and measurement error (Ocke and Kaaks, 1997). Unlike drugs, very few nutritional studies depend on reliable end point measurements. There is a pressing need for dietary biomarkers to better capture exposure; however, few have been identied to date (Jenab et al., 2009).