Eur J Clin Nutr. 2002 Aug; 56(8): 765-70.

Assessment of iodine intake in vegans: weighed dietary record vs duplicate portion technique.

Lightowler HJ, Davies GJ.

Nutrition and Food Science Group, School of Biological and Molecular Sciences, Oxford Brookes University, Oxford, UK.

OBJECTIVE: To compare iodine intakes estimated from weighed dietary records with iodine intakes obtained by direct analysis of duplicate diets in a group of vegans. DESIGN: Cross-sectional study. SETTING: London and the south-east of England. SUBJECTS: Thirty-three vegans consuming their habitual diet were recruited through the UK Vegan Society; 26 subjects (11 males, 15 females), age 21-84 y, completed the study. INTERVENTIONS: Iodine intakes were estimated from 4 day weighed dietary records and compared with iodine intakes obtained by direct analysis of concurrent 4 day duplicate diets. RESULTS: There was wide variation in iodine intakes. Mean daily iodine intake in males was significantly lower (P<0.05) when estimated from dietary records (42 microg) compared with that analysed from duplicate diets (137 microg). Conversely, in females the mean daily iodine intake from dietary records (1448 microg) was higher (P=0.43) than from duplicate diets (216 microg). Variation in iodine intakes determined by the two different methods may be attributed to the absence of iodine content of some foods, in particular foods suitable for vegan consumption, in food composition tables and the variability in iodine content of seaweed. CONCLUSIONS: The use of current food tables to estimate iodine intake in vegans is limited. It is not always practical to determine iodine intake using the duplicate portion technique, therefore more reliable information on iodine content of foods, incorporating the variation within foods, is needed.