This paper describes the development of a Quantitative Food Frequency Questionnaire (QFFQ) to be applied in a case-control study on diet and breast cancer in João Pessoa. A 24-hour Dietary Recall (24hDR) was obtained from 100 women, aged 20-75 years, from distinct socio-economic strata, using public health services. Foods were grouped in food items, according to similarity of nutritional value per food portion and/or sources of food nutrients (energy, carbohydrates, lipids, protein, vitamin C and retinol). We calculated the percentual contribution of each nutrient. Utilizing Block's formula , and criteria for grouping food itens included contribution of 90% for any nutrient, to be source of one or belongs to population food habit, or belong to the food habit of the population. QQFQ was designed with 68 food items. To calculate portion sizes, the frequency distribution of equivalent-gram weights for 24hDR was divided into percentiles, with P50 corresponding to the reference portion (medium), and small, large and extra-large to P25, P75 and P100, respectively.
Food intake; Breast cancer; Case-control
