Dairy food consumption is beneficially linked with iodine status in US children and adults: National Health and Nutrition Examination Surveys 2001–2018

OBJECTIVES: The objective of this study was to determine the association between the consumption of dairy foods with urinary iodine concentration (UIC) and iodine deficiency risk in a nationally representative sample of the US population. DESIGN, SETTING AND PARTICIPANTS: 24-hour dietary recall data and laboratory data for UIC (μg/l) from subjects 2+ years old US population participating in National Health and Nutrition Examination Surveys 2001–2018 were used (n 26 838) for analyses after adjusting for demographic covariates. Significant associations were assessed at P < 0·05. RESULTS: Mean intakes of total dairy were 2·21, 2·17 and 1·70 cup equivalents (cup eq) among those 2–8, 9–18 and 19+ years, respectively. Of the dairy components, intake of milk was highest followed by cheese and yogurt for all age groups. Total dairy intakes were positively associated with UIC among those 2–8 years (β = 29·9 ± 9·9 μg/l urine/cup eq dairy) and 9–18 years (β = 26·0 ± 4·8 μg/l urine/cup eq dairy) but not associated among those 19+ years. Total dairy intakes were associated with lowered risks (30 %, 21 % and 20 % for among 2–8, 9–18 and 19+ years, respectively) of being classified as iodine insufficient (UIC < 100 μg/l) or lowered risk (47 %, 30 % and 26 % among 2–8, 9–18 and 19+ years, respectively) of being classified as iodine severely deficient (UIC < 20 μg/l). CONCLUSIONS: The results indicate that dairy foods are beneficially associated with UIC and lowered iodine deficiency risk.