Validity and systematic error in measuring carotenoid consumption with dietary self-report instruments

Area of Science:

• Nutrition Science
• Epidemiology
• Biostatistics

Background:

• Carotenoids in fruits and vegetables are linked to cancer protection.
• Accurate dietary intake measurement is crucial for diet-disease association studies.

Purpose of the Study:

• To develop and apply a measurement error model for assessing dietary assessment tools.
• To estimate the validity, systematic error, and reliability of two self-report methods for carotenoid intake.

Main Methods:

• A measurement error model was used.
• Carotenoid intake was assessed via repeated 24-hour recalls, a food frequency questionnaire (FFQ), and plasma biomarkers.
• The model was applied to 1,013 participants in the Women's Healthy Eating and Living Study.

Main Results:

• Validity coefficients were 0.44 for 24-hour recalls and 0.39 for FFQs.
• Systematic error constituted over 22% of measurement error variance for recalls and over 50% for FFQs.
• Both methods exhibited substantial measurement error.

Conclusions:

• Individual self-report dietary methods can introduce significant bias and error in diet-disease studies.
• Employing multiple dietary assessment methods may enhance the accuracy of true dietary intake estimation.