Measuring dietary change in a diet intervention trial: comparing food frequency questionnaire and dietary recalls.

Measurement of dietary change was assessed in a systematic quota subsample (n = 397) of women recruited into the Women's Healthy Eating and Living Study between 1996 and 1998, a multicenter, randomized dietary intervention trial among breast cancer survivors. Women from the intervention and comparison arms completed the Arizona Food Frequency Questionnaire (AFFQ) and 24-hour dietary recalls at baseline (prerandomization) and at year 1 (postrandomization). Both dietary measurement methods demonstrated significant changes in intake of key intervention-associated nutrients at year 1 in the intervention group subjects compared with minimal or no change in the comparison group subjects. The reliability of the AFFQ and recalls was measured in the comparison group and showed correlations of 0.63 and 0.43, respectively. Both instruments captured differences in dietary intake associated with the diet intervention. These results demonstrate the utility of using a multimode, multimethod approach (AFFQ and 24-hour dietary recalls) to measure differences in self-reported dietary intake over time as shown in this dietary intervention trial being conducted among breast cancer survivors.