Development of a food frequency instrument: ethnic differences in food sources.

Dietary intake was assessed among 431 black, white, and Mexican American men and women in southeast Texas using 24-hour dietary recall interviews. These data were collected to provide information on ethnic-specific food sources of selected nutrients; this information was used to construct a food frequency questionnaire for a study of nutrient intake and cancer. Nutrient content of total fat, total vitamin A, and vitamin C was determined for all foods consumed and was aggregated across unique food codes. These aggregated food codes were then ranked according to the contribution of each food to the total population intake of each nutrient. Ethnic differences existed in food sources of nutrients that would not be identified if data from only the analysis of the combined data set were used. Generally, however, the food sources identified from analyses of the combined data set included those foods that were important nutrient sources for each of the ethnic groups as well.