Evaluation of a semi-quantitative food frequency questionnaire to estimate iodine intake.
OBJECTIVE
To evaluate a food frequency questionnaire (FFQ) used to assess the dietary intake of iodine.


METHODS
The iodine intake determined by the FFQ was compared with 4-day dietary records and with iodine excretion in 24 h urine samples in a subgroup of participants in a cross-sectional study of iodine intake and thyroid diseases in Denmark. Furthermore, the intake of fish determined from the FFQ was compared with the intake of fish from a simple record kept for 3 months.


METHODS
Women aged 25-30 y and 60-65 y.


RESULTS
Median iodine intake was similar when determined from the FFQ and from dietary records and the correlation between these measures was 0.52 (P < 0.001). Iodine intake was higher than iodine excretion (P < 0.001). The cross-check questions in the FFQ (for example the question 'How often did you get any kind of fish?') underestimated the intake. In contrast, the intake of a specific fish tended to be overestimated by the FFQ when compared with the 3 month record of fish intake.


CONCLUSIONS
The FFQ can be used to classify subjects into low and high iodine intake groups, but the level of iodine tends to be overestimated.
Rasmussen
L B
LB
Institute of Food Research and Nutrition, Danish Veterinary and Food Administration, Søborg, Denmark. lbr@fdir.dk
Ovesen
L
L
Bülow
I
I
Jørgensen
T
T
Knudsen
N
N
Laurberg
P
P
Perrild
H
H
D000328:Adult; D000368:Aged; D000818:Animals; D015415:Biomarkers; D003718:Denmark / Q000453:epidemiology; D015930:Diet Records; D005260:Female; D005399:Fishes; D006801:Humans; D007455:Iodine / Q000008:administration & dosage* / Q000652:urine*; D008875:Middle Aged; D015596:Nutrition Assessment; D015203:Reproducibility of Results; D017747:Seafood; D012680:Sensitivity and Specificity; D011795:Surveys and Questionnaires; D013959:Thyroid Diseases / Q000453:epidemiology
D015415:Biomarkers; D007455:Iodine