A 7-item versus 31-item food frequency questionnaire for measuring fruit, juice, and vegetable intake among a predominantly African-American population

Objective This study sought to determine which of 2 fruit and vegetable foo d frequency questionnaires (FFQs) most closely approximated intake measured by the average of four 24-hour dietary recalls. Design Participants completed either a 31-item FFQ (n = 70) or 7-item FFQ ( n = 76) on 2 occasions approximately 2 weeks apart. During the interval bet ween FFQs, participants provided four 24-hour dietary recalls via telephone interview. Subjects/setting Participants were 146 persons with food preparation respon sibilities in families of students in grades 3 through 5. Respondents were predominantly African-American women in Atlanta, Ga. Statistical analysis Pearson correlation coefficients of log-transformed va lues estimated the reliability of each FFQ and compared FFQ estimates to re ference values. The intraclass correlation coefficient evaluated consistenc y across 24-hour recalls. Results The first FFQs overestimated intake approximately twofold. The 31-i tem FFQ estimates exceeded 7-item FFQ estimates by approximately 30%. Corre lations with recall estimates were high for the 7-item FFQ and moderate to low for the 31-item FFQ. The second FFQ estimates were more highly correlat ed to reference values. From the first to the second administration, 7-item FFQ estimates dropped from 5.2 to 2.7 servings, and 31-item FFQ estimates dropped from 6.7 to 3.5 servings. Neither FFQ produced highly reliable esti mates. Conclusions Mean total fruit and vegetable consumption was closer to refere nce estimates for the first 7-item FFQ and the second 31-item FFQ. The 7-it em FFQ correlated more highly with reference estimates than did the 31-item FFQ. Therefore, we conclude that for African-American adults, a 1-time-adm inistered FFQ using 7 broad food categories correlates more highly with ref erence values than a FFQ using 31 individual fruit and vegetable items.