Use of a brief food frequency questionnaire for estimating daily number of servings of fruits and vegetables in a minority adolescent population.

The validity of the 5 A Day for Better Health Program food frequency questionnaire (5 A Day FFQ) for estimating fruit and vegetable consumption was examined in a sample of 156 African-American adolescents aged 10 to 14 years. To determine validity, the correlation between 5 A Day FFQ fruit, juice, and vegetable intake and 3-day intake measured by direct observation was assessed. Correlations were calculated separately by food type (ie, fruits, juices, and vegetables) and sex and age to determine whether the accuracy of youths' recording differed based on these factors. Paired-samples t tests were used to test for differences between 5 A Day FFQ and observed intake estimates. The ability of the 5 A Day FFQ to correctly classify youths according to intake level (ie, intake of five or more daily servings) was also examined. The 5 A Day FFQ intake was significantly correlated with observed intake (r=0.39; P<0.01). Correlations were weaker by food type (r=0.15 to r=0.28) and did not differ based on youths' sex or age. Mean 5 A Day FFQ intake (6.74+/-6.00 servings) was considerably higher than mean observed intake (5.41+/-1.51 servings), and this was a result of the overestimation of vegetable intake. Sensitivity, specificity, and positive and negative predictive values of the 5 A Day FFQ were 67.1%, 68.6%, 63.5%, and 71.9%, respectively. Findings suggest that the 5 A Day FFQ may be more useful as a screening tool for identifying African-American adolescents most in need of intervention than for estimating youths' mean intake in dietary intervention programs.