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 basic commodities was designed for the Elderly Nutrient and Health Survey in Taiwan (NAHSIT) to collect participants' usual intake of the previous month. We have examined the validity this SFFQ as assessed by multiple 24-hour dietary recall (n=81) and biomarkers (n=1473). All questionnaires were completed by face-to-face interview and fasting blood 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 intake from the FFQ and dietary recalls ranged from 0.132 to 0.678 for men; 0.052 to 0.759 for women. For food weight, the trends were similar to frequency findings. For biomarkers, the most correlated were dairy intake frequency judged by 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 followed in overall validity. The SFFQ measured the food patterns of elderly NAHSIT elders with validity high for dairy and good for fish, and fruit intakes in both genders.