Evaluation of urinary iodine excretion as a biomarker for intake of milk and dairy products in pregnant women in the Norwegian Mother and Child Cohort Study (MoBa)

Eur J Clin Nutr. 2009 Mar;63(3):347-54. doi: 10.1038/sj.ejcn.1602952. Epub 2007 Dec 5.

Abstract

Background/objectives: Milk and dairy products are the main sources of iodine in the Norwegian diet. This is due to a high consumption of milk and dairy products combined with a relatively high concentration of iodine in milk because of mandatory iodine fortification of cow fodder. The aim of the present study was to investigate the relation between 24-h urinary iodine excretion and estimated dietary intake, and to explore the use of 24-h urinary iodine excretion as a possible biomarker for the intake of milk and dairy products when assessing the validity of a new food frequency questionnaire for pregnant women participating the Norwegian Mother and Child Cohort Study (MoBa).

Subject/methods: 119 women participated in a validation study. Iodine was analyzed in 24-h urine. Dietary intakes were estimated by a food frequency questionnaire (FFQ) and a 4-day weighed food diary (FD). Using linear regression, predictors of urinary iodine excretion were identified. The triangular method was applied to calculate validity coefficients.

Results: Significant predictors of 24-h urinary iodine excretion were: intake of dairy products, iodine-containing supplements and intake of fruit/vegetables. Fish/seafood intake and time of the year influenced 24-h urinary iodine excretion, although not significantly. The validity coefficients observed for total intake of dairy products were 0.65, 0.94 and 0.52 for the FFQ, the FD and the 24-h urinary iodine excretion, respectively.

Conclusions: The present study showed that 24-h urinary iodine excretion may be a useful biomarker for validating the intake of milk and dairy products in pregnant Norwegian women.

Publication types

  • Research Support, Non-U.S. Gov't
  • Validation Study

MeSH terms

  • Adult
  • Animals
  • Biomarkers / urine
  • Cohort Studies
  • Dairy Products*
  • Diet Records
  • Diet*
  • Female
  • Fishes
  • Humans
  • Iodine / administration & dosage
  • Iodine / urine*
  • Linear Models
  • Milk*
  • Norway
  • Pregnancy
  • Surveys and Questionnaires*
  • Urinalysis
  • Young Adult

Substances

  • Biomarkers
  • Iodine