Invited commentary: five hundred twenty-five thousand, six hundred calories, how do you measure diet in a year?

Nearly 4 decades after its landmark validation study, researchers undertook a major comprehensive reevaluation of the semiquantitative food frequency questionnaire (FFQ). Although it has evolved with trends in science and our expanding food environment, this FFQ has been administered continuously to over 250 000 US cohort participants for several decades and has contributed enormously to our understanding of the role long-term diet plays in health and disease across the lifespan. Nonetheless, it is critical that the field take time to validate, recalibrate, and reassure researchers that the FFQ continues to generate useful estimates of dietary intake. There are persistent misconceptions among both nutritional epidemiologists and the FFQ’s critics about what the FFQ can and cannot measure that require regular re-education on the principles underlying FFQ development and validation. Thus, the carefully conducted validation study by Gu et al (Am J Epidemiol. 2024;193(1):170-179) provides an important benchmark for nutrition science, underscoring the continued value and utility that the FFQ brings to epidemiologic research.