Studying a population undergoing nutrition transition: a practical case study of dietary assessment in urban South African adolescents.

The South African Medical Research Council food frequency questionnaire (FFQ) and protocol was used to determine food intake in 83 adolescents from the Birth To Twenty study. The FFQ was piloted on a small group (n=8). Specific problems which resulted in overestimation of energy intake were identified. The protocol was modified and administered to the remainder of the adolescents and their caregivers. Reasonable energy intakes were obtained, and time spent completing the FFQ was reduced. The modified protocol was more successful in determining habitual food intake although it would benefit from validation against other dietary intake techniques.