Validation of a simplified food frequency questionnaire as used in the Nutrition and Health Survey in Taiwan (NAHSIT) for the elderly

A 28-item simplified food frequency questionnaire (SFFQ) combined with 9 open questions about staples was designed for the Elderly Nutrient and Health Survey in Taiwan (NAHSIT) to collect information on participants' usual food intake of the previous month. We have examined the validity of this SFFQ via comparison with data on multiple 24-hour dietary recall (n=81) and biomarkers (n=1473). All questionnaires were completed by faceto-face interview and fasting blood samples were taken. Thirty seven males and 44 females were randomly selected from NAHSIT participants. Of these, 31 and 50 subjects completed 2 or 3 24-hour dietary recalls within one month, respectively. Mean daily intake frequencies for each food group were calculated from the SFFQ and 24-hr recalls, respectively. Spearman rank correlation coefficients between frequencies of food group obtained from the FFQ and from dietary recalls ranged from 0.132 to 0.678 for men; 0.052 to 0.759 for women. Correlation coefficients between frequency and food weight were similar. When validated by nutrient status, the most correlated was dairy intake frequency judged by 24-hour vitamin B-2 and calcium intakes and by erythrocyte glutathione reductase (EGRAC) for B-2 functionality, where the correlation coefficients were, respectively, 0.533, 0.518 and -0.205 for men; 0.494, 0.475 and -0.174 for women; fish and fruit frequency followed in overall validity. The SFFQ measured the food patterns of NAHSIT elders with validity high for dairy and good for fish and fruit intakes in both genders.