Assessment of dietary intake by self-reports and biological markers

Accurate assessment of dietary intake is crucial in the field of nutrition. In this chapter, different dietary assessment methods and types of biomarkers of dietary intake, their strengths and weaknesses, and the importance of examining the sources of error and variation are described. There is no best method of diet assessment for all purposes; therefore, the investigator has to select the method appropriate for the purpose and target group of the survey. Performing validation studies is essential to further improve dietary assessment methods, for a better interpretation of dietary assessment results, and for the correction of associations with outcomes for measurement errors, so that such associations are not obscured by these errors. Innovations in dietary assessment methods and validated biomarkers of intake will certainly improve assessments, but they are not the solution to all of the inherent problems in applying dietary assessment methods.