Validation of a food frequency questionnaire for assessing the intake of food groups and nutrients in adults

ObjectiveTo validate a food frequency questionnaire used to assess food consumption among adults in a Brazilian cohort.MethodsCross-sectional study conducted on 100 adults. Food intake was assessed by the food frequency questionnaire and by two 24-hour recalls. Validation was performed for nutrients (n=19) and food groups (n=21).ResultsModerate deattenuated Pearson's correlation coefficients (>0.4) were observed for the consumption of dairy products, breads and crackers, rice, pasta and tubers, leafy vegetables, other vegetables, fats, sweetened drinks, sandwiches and savory snacks, and nuts, and for the following nutrients (deattenuated and adjusted for energy intake): fiber, calcium, and vitamins A, B2, and C. Based on almost all food groups and nutrients assessed, >= 70% of the individuals were classified into the same or adjacent quartile for both methods, except for red and pork meat, snacks, nuts, phosphorus, potassium, and vitamin B3. The food groups and nutrients with fair kappa agreement (>0.2) were: dairy products, other vegetables, sweetened drinks, breakfast cereals, energy, carbohydrate, iron, and vitamin A.ConclusionThe food frequency questionnaire has proven useful for estimating the intake of some nutrients and food groups of the subjects evaluated. Only the intake of red and pork meat, snacks, nuts, vitamin B3, phosphorus and potassium were estimated with less accuracy.