A 3-DAY WEIGHED FOOD RECORD AND A SEMIQUANTITATIVE FOOD-FREQUENCY QUESTIONNAIRE ARE VALID MEASURES FOR ASSESSING THE FOLATE AND VITAMIN-B-12 INTAKES OF WOMEN AGED 16 TO 19 YEARS

The purpose of this study was to validate a food-frequency questionnai re (FFQ) and a 3-d weighed food record (3d-WFR) by comparing nutrient intakes estimated using these methods with serum folate, RBC folate an d serum vitamin B-12 concentrations in 105 females aged 16-19 y. Durin g an early morning clinic visit, subjects completed a self-administere d, 116-item FFQ, blood was collected and they were trained to complete a 3d-WFR. Folate intakes as determined by the 3d-WFR (r = 0.65, P < 0 .01) exhibited a stronger association with serum folate than did intak es from the FFQ (r = 0.48, P < 0.01) (P = 0.017). The correlations bet ween folate intakes and RBC folate as determined by the FFQ (r = 0.42, P < 0.01) and 3d-WFR (r = 0.50, P < 0.01) methods did not differ. Vit amin B-12 intakes showed only a modest association with serum vitamin B-12 when supplement users were included in the analyses (FFQ, r = 0.2 5, P < 0.05; 3d-WFR, r = 0.32, P < 0.05). After excluding supplement u sers from the analyses, the relationship between vitamin B-12 intakes as determined by FFQ and serum vitamin B-12 was no longer significant. Median daily folate intakes (346 vs. 212 mu g) and vitamin B-12 (4.9 vs. 1.9 mu g) estimated from the FFQ were higher than those obtained f rom the 3d-WFR. In sum, these data suggest that both the FFQ and 3d-WF R are valid measures of assessing the folate intake of young women, an d both appear to be useful in determining vitamin B-12 intake when sup plemental users are included. The markedly different conclusions about absolute folate and vitamin B-12 intakes obtained using these two die tary methodologies should be taken into consideration when making reco mmendations about optimal folate intakes in relation to disease preven tion.