Evaluating self-reported retrospective average daily fruit, vegetable, and egg intake: Trustworthy-Sometimes!

Retrospective self-reports are commonly used to assess dietary intake. Yet, their use is criticized as it is unclear whether the underlying assumptions for valid self-reports are met: Individuals have to consider the behavior of all days in the retention interval and weigh the behavior of all days equally. This study examines whether these assumptions for retrospective self-reports are met and whether interindividual differences in self-report performance are relevant regarding these assumptions. Ninety-two participants aged 18-61 years participated in seven sequential 24-h recalls and one retrospective 7-day recall concerning their intake of fruit, vegetables, and eggs. A multiple linear regression approach was used to examine the relation between the daily reported dietary intake and the 7-day recall. In the overall sample, the requirements for retrospective self-reports were not tenable. Distinguishing good and poor self-reporters based on a rational criterion showed that the requirements can be taken as given for good self-reporters, whereas poor self-reporters base their retrospective self-reports mostly on recency effects. The underlying requirements for retrospective self-reports appear to be met in two thirds of the sample, supporting the use of retrospective self-reports to capture dietary behavior. Future research should investigate characteristics separating good from poor self-reporters.