Establishing the Iodine Requirement in Infancy
Condition: Focus: Establish the Iodine Requirement During Infancy
Study type: Interventional

Summary: 
      The objective of this study is to define the amount of dietary iodine needed per day during
      the first six months of life. The hypothesis is that the current recommended iodine intake in
      infants is set too high.
    

Detailed description: 
      Iodine is an essential trace element for human health and an integral component of the
      thyroid hormones. Thyroid hormones regulate normal growth and development, particularly of
      the brain. Iodine deficiency results in low levels of thyroid hormones that can impair brain
      development and lower intelligence. Infants have only small iodine stores at birth and are
      entirely dependent on iodine provided by breast milk or infant formula. However, the exact
      amount of daily iodine that infants need for healthy development is poorly understood and
      there is insufficient data to define an Estimated Average Requirement (EAR) for this age
      group.

      The current recommendation for dietary iodine intake for 0-6 month (mo) old infants of 110
      µg/day is only an adequate intake (AI), in the absence of an EAR. This AI is based on the
      iodine intake in breast fed infants from breast milk iodine concentration (BMIC) measured in
      U.S. women during a period when overall iodine intakes in the U.S. population were excessive.
      The AI sharply disagrees with the current WHO recommendation for assessment of infant iodine
      nutrition based on excretion of iodine in the urine. The discrepancy makes assessment and
      monitoring of iodine status at this age problematic and has led to major confusion on how to
      interpret adequate iodine intake and optimal iodine status.

      The objective of this study is to measure the daily iodine retention from dietary iodine and
      define the physiological iodine requirement (the EAR) during the first six months of life.
      The study hypothesis is that the AI is set too high and its use in assessing iodine intake
      and status overestimates the prevalence of iodine deficiency in infants.

      The study will be a metabolic balance study of breast milk consumption and three
      dose-response cross-over arms of iodine enriched infant formula milk in 60 healthy 2-3 mo old
      infants (30 breast fed and 30 formula fed). Breast fed infants will be exclusively and
      unrestrictedly breast fed by the mother and the breast milk consumption will be monitored for
      4 days by weighing the infants before and after each feeding session. Formula fed infants
      will be randomly allocated to three 11 days cross-over periods of exclusive consumption of
      infant formula milks (IFM) providing 60 µg I/day, 110 µg I/day and 220 µg I/day. The iodine
      intake will be monitored by recording the amount of infant formula milk fed to the infants.
      The iodine excretion will be measured from complete collections of urine and feces for a
      4-day period for each arm. The iodine retention will be calculated from the difference
      between measured iodine intake and excretion. Analytical determination of the iodine content
      in biological samples will be done by mass spectrometry after digestion and iodine
      extraction. The sample size is based on an estimated dose-response of the different levels of
      dietary iodine on iodine excretion.
    

Intervention name(s): Infant formula; Breast milk
Intervention type(s): Dietary Supplement; Other
Intervention description(s): To establish dose-response relationships, formula-fed infants will be randomly allocated to three 11-day cross-over periods of exclusive consumption of infant formula providing different amounts of iodine. All iodine levels are within the required iodine levels for infant formula following the regulations of the United States, the European Union, Switzerland and New Zealand.; Unlimited breast feeding
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Basic Science