Calibration of a food frequency questionnaire developed for the South Asian community in the United Kingdom

An interview administered food frequency questionnaire (FFQ) consisting of 75 food items was developed and calibrated against a four day weighed record (WR). The FFQ was also calibrated against a proxy for biomarker, the energy intake/basal metabolic rate ratio (EI/BMR). A total of 58 subjects (35 women, 23 men) aged between 19 and 76 years of Pakistani and Indian origin in Southampton, United Kingdom (UK) participated in this calibration study. The results for men and women combined together suggested reasonable agreement between FFQ and WR estimates of intake with Spearman rank correlation coefficient ranging between 0.26 and 0.38 (energy unadjusted). Gender specific agreement was however, poor. The percent mean difference between nutrient estimates by FFQ and WR was in general within 10% for energy, fat and protein in women while in the range of 11% to 25% in men. The percent mean difference for other nutrients such as sugar and dietary fibre ranged between 18% and 99% in men and women; while was 9% and 6% for starch in men and women respectively. The ranking of subjects into the thirds of distribution was poor with gross misclassification in the range of 5% to 14% in men and 15% to 29% in women. Comparison of both FFQ and WR with EI/BMR ratio showed that there were more underreporters of energy intake when reporting intake using WR than FFQ in both men and women. Based on these results, it was concluded that further development of the FFQ was needed before the FFQ could be used to evaluate the usual dietary intake in the South Asian population.