Comparison of estimated nutrient intakes by food frequency and dietary records in adults.

Sixteen days of dietary recall and records collected over 1 year for 228 respondents were compared with an estimate of "usual" diet based on a 116-item food frequency questionnaire (FFQ) for the study year. Respondents were white and black men and women aged 24 to 51. Mean energy values for the total group were 2,111 kcal for the recall/records and 2,766 kcal for the FFQ, a 31% difference. The mean food energy and nutrient values obtained by the FFQ were consistently and significantly higher than the mean recall/record values for all four race-sex groups, although the degree of difference varied by nutrient, food group, and demographic characteristics of the respondents. For the nutrients compared, the smallest difference between methods was for protein--27% for the total group. The greatest difference was for vitamin A--123% for the total sample. Sex-race specific correlation coefficients between methods were relatively high for calcium, vitamin C, and iron.