Is it time to abandon the food frequency questionnaire?

Although painful to admit, it is possible that epidemiologists have been deluded in their acceptance of food frequency questionnaires (FFQ) as the standard tool for dietary assessment in large studies of diet and cancer. The substantial limitations of FFQs have been known for some time (1) and published studies based on FFQ-derived data have long included in their discussion sections a litany of weaknesses due to suboptimal dietary assessment. However, few of us expected the astonishingly poor measurement characteristics of FFQs when compared with doubly labeled water (a gold standard for energy intake; ref. 2), nor had we expected to learn that diet and cancer associations detected when dietary assessment is based on dietary biomarkers (e.g., ref. 3) or food records (4) are undetectable when based on FFQs. We are facing a crisis: hundreds of millions of dollars and many scientists’ careers have been invested in studies using only FFQs to measure diet, but it is possible that these studies have not been, and will not be, able to answer many if not most questions about diet and cancer risk. This commentary has two broad functions. First, it describes how FFQs were developed and why they became the standard measure of diet for epidemiologic research. Second, it suggests several directions for future research and practice to improve dietary assessment in studies of diet and cancer.