A 7-item versus 31-item food frequency questionnaire for measuring fruit, juice, and vegetable intake among a predominantly African-American population
Cl. Warneke et al., A 7-item versus 31-item food frequency questionnaire for measuring fruit, juice, and vegetable intake among a predominantly African-American population, J AM DIET A, 101(7), 2001, pp. 774-779
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.