Reduced precision of self-rbported energy intake in a minority population

Prior to the start of studies of diet and disease in different racial groups, we attempted to validate instruments for assessing dietary intake. We compared dietary energy intake (Ein) using the Block/NCI food frequency questionnaire (FFQ) or 14 day dietary record with total energy expenditure (EE) measured for 14 days using doubly labeled water. Study I was performed in young and middle aged women of iow socioeconomic status. Ein obtained using the FFQ averaged 2550±590 vs. EE=2650±390 kcal/d in II Caucasian women, but there was underreporting in I i African-Am eric an women (Ein=2100±1250 vs. EE=2510±690 kcal/d). Study II was performed in young and middle aged women who had at least one year of college education (median=4 y). Ein obtained by diary averaged 2450±210 vs EE=2710±360 kcal/d in 10 Caucasian women and Ein=2320±560 vs. EE=2580±360 kcal/d in 10 African-American women. Neither difference was significant. In both studies, the variance in self-reported intake relative to EE was greater for African Americans than Caucasians (p<0.05) and was not obviated by education level. None of this variance was explained by energy requirements as Ein and EE did not correlate in the African Americans from either study. These self-reported intake instruments are subject to a large, unexplained random error in African-American women.