INCORPORATING FAT-MODIFIED FOODS INTO A FOOD FREQUENCY QUESTIONNAIRE IMPROVES CLASSIFICATION OF FAT INTAKE

Objective To determine the extent to which incorporating fat-modified foods into a food frequency questionnaire influences the agreement of energy and nutrient estimates with estimates obtained from food record s. Design Subjects completed four 2-day food records at 3-month interv als. At the end of the recording period, a food frequency questionnair e was administered to assess usual daily intake during the preceding y ear. Subjects/setting One hundred and three subjects selected from a p opulation-based sample of adults participating in the Beaver Dam Eye S tudy. Statistical analyses performed Subjects were categorized into th ree groups on the basis of their frequency of consumption of fat-modif ied foods. For each group, correlations were calculated between food r ecord estimates and estimates obtained from the original food frequenc y questionnaire, the original with a low-fat option, and the fat-modif ied questionnaire. Results For persons categorized as high consumers o f fat-modified foods, incorporating questions regarding the consumptio n of these products resulted in higher correlations with food record e stimates (original vs fat-modified version) for percentage of energy f rom total fat (.32 vs .47), saturated fat (.20 vs .41), oleic acid (.3 2 vs .50), and linoleic acid (.40 vs .46). High consumers differed in several characteristics that could be associated with disease risk (eg , higher ratios of serum total cholesterol to high-density lipoprotein cholesterol). Conclusions Failure to account for the consumption of f at-modified foods in epidemiologic studies may result in misclassifica tion of fat exposures. Because patterns of misclassification could be different for those at risk for disease. results of epidemiologic stud ies could be biased if these foods are excluded. Thus, incorporating f at-modified foods into food frequency questionnaires will improve the ability of researchers to correctly classify fat exposures and to eval uate potentially important relationships between fat intake and diseas e risk.