title: A dose-response crossover iodine balance study to determine iodine requirements in early infancy.
abstract: BACKGROUND
  Optimal iodine intake during infancy is critical for brain development, but no estimated average requirement (EAR) is available for this age group.
  
  
  OBJECTIVE
  We measured daily iodine intake, excretion, and retention over a range of iodine intakes in early infancy to determine the minimum daily intake required to achieve iodine balance.
  
  
  METHODS
  In a dose-response crossover study, we randomly assigned healthy infants (n = 11; mean ± SD age 13 ± 3 wk) to sequentially consume over 33 d 3 infant formula milks (IFMs) containing 10.5, 19.3, and 38.5 μg I/100 kcal, respectively. Each IFM was consumed for 11 d, consisting of a 6-d run-in period followed by a 4-d balance period and 1 run-out day.
  
  
  RESULTS
  Iodine intake (mean ± SD: 54.6 ± 8.1, 142.3 ± 23.1, and 268.4 ± 32.6 μg/d), excretion (55.9 ± 8.6, 121.9 ± 21.7, and 228.7 ± 39.3 μg/d), and retention (-1.6 ± 8.3, 20.6 ± 21.6, and 39.8 ± 34.3 μg/d) differed among the low, middle, and high iodine IFM groups (P < 0.001 for all). There was a linear relation between daily iodine intake and both daily iodine excretion and daily iodine retention. Zero balance (iodine intake = iodine excretion, iodine retention = 0 μg/d) was achieved at a daily iodine intake of 70 μg (95% CI: 60, 80 μg).
  
  
  CONCLUSIONS
  Our data indicate the iodine requirement in 2- to 5-mo-old infants is 70 μg/d. Adding an allowance for accumulation of thyroidal iodine stores would produce an EAR of 72 μg and a recommended dietary allowance of 80 μg. This trial was registered at clinicaltrials.gov as NCT02045784.
authors.affiliation: Human Nutrition Laboratory, Institute of Food Nutrition and Health, ETH Zurich, Zurich, Switzerland; susanne.dold@hest.ethz.ch.
authors.forename: Susanne
authors.initials: S
authors.lastname: Dold
authors.affiliation: Human Nutrition Laboratory, Institute of Food Nutrition and Health, ETH Zurich, Zurich, Switzerland; Iodine Global Network, Zurich, Switzerland;
authors.forename: Michael B
authors.initials: MB
authors.lastname: Zimmermann
authors.affiliation: Centre of Excellence for Nutrition, North-West University, Potchefstroom, South Africa; and.
authors.forename: Jeannine
authors.initials: J
authors.lastname: Baumgartner
authors.affiliation: Human Nutrition Laboratory, Institute of Food Nutrition and Health, ETH Zurich, Zurich, Switzerland;
authors.forename: Tabea
authors.initials: T
authors.lastname: Davaz
authors.affiliation: Human Nutrition Laboratory, Institute of Food Nutrition and Health, ETH Zurich, Zurich, Switzerland;
authors.forename: Valeria
authors.identifier: http://orcid.org/0000-0002-7867-9960
authors.initials: V
authors.lastname: Galetti
authors.affiliation: Division of Gastroenterology and Nutrition, University Children's Hospital, Zurich, Switzerland.
authors.forename: Christian
authors.initials: C
authors.lastname: Braegger
authors.affiliation: Human Nutrition Laboratory, Institute of Food Nutrition and Health, ETH Zurich, Zurich, Switzerland; Iodine Global Network, Zurich, Switzerland;
authors.forename: Maria
authors.initials: M
authors.lastname: Andersson
mesh_terms: D015415:Biomarkers / Q000032:analysis / Q000097:blood / Q000652:urine; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005243:Feces / Q000737:chemistry; D005260:Female; D005527:Food, Fortified; D006801:Humans; D007223:Infant; D041943:Infant Formula; D007227:Infant Nutritional Physiological Phenomena; D007408:Intestinal Absorption; D066237:Intestinal Elimination; D007455:Iodine / Q000008:administration & dosage* / Q000032:analysis / Q000378:metabolism / Q000652:urine; D008297:Male; D009751:Nutritional Requirements; D009752:Nutritional Status; D064167:Recommended Dietary Allowances; D065667:Renal Elimination; D013557:Switzerland; D014131:Trace Elements / Q000008:administration & dosage* / Q000032:analysis / Q000378:metabolism / Q000652:urine
chemical_list: D015415:Biomarkers; D014131:Trace Elements; D007455:Iodine
keywords: infants; iodine; iodine balance; iodine deficiency; iodine intake; iodine requirement