Evaluation of three short dietary instruments to assess fruit and vegetable intake: the National Cancer Institute's food attitudes and behaviors survey.

BACKGROUND: Fruit and vegetable (F/V) intake assessment tools that are valid, reliable, brief, and easy to administer and code are vital to the field of public health nutrition.

OBJECTIVE: To evaluate three short F/V intake screeners (ie, a 2-item serving tool, a 2-item cup tool, and a 16-item F/V intake screener) among adults using multiple 24-hour dietary recalls (24-hour recalls) as the reference instrument and evaluate test-retest reliability of the screeners across a 2- to 3-week time period.

DESIGN: Validity and reliability study.

PARTICIPANTS/SETTING: Two hundred forty-four adults for the validity study and 335 adults for test-retest reliability.

STATISTICAL ANALYSES PERFORMED: Median values for F/V intakes were calculated for the screeners and 24-hour recalls. The Wilcoxon signed rank test was used to compare screeners with the 24-hour recalls. Deattenuated Pearson correlations were reported for validity and intraclass correlation coefficient used for reliability.

RESULTS: The estimated median daily servings/cups of F/V for the 2-item serving screener was lower, for the 2-item cup screener was equivalent for men but higher for women, and for the 16-item F/V intake screener were about the same when compared with 24-hour recall values. The deattenuated correlations comparing the 24-hour recalls with the screeners were positive but weak for the 2-item serving screener, and were positive and moderate in strength for the 2-item cup and 16-item F/V intake screeners. The test-retest intraclass correlation coefficients were all positive and fairly strong for all of the screeners.

CONCLUSIONS: Although dietary screeners offer a more cost-effective, less burdensome way to obtain gross estimates to rank individuals with regard to F/V intake, these methods are not recommended for assessing precise intake levels.