Study on Physiologic Requirement and Dietary Recommended Nutrient Intake (RNI) of Iodine in Children
Condition: Nutritional Requirements
Study type: Observational

Summary: 
      Iodine is one of essential micronutrient for human, both iodine deficiency and excess will be
      harmful for human health. Children is the susceptible population to iodine nutrition, and
      studies show that even mild iodine deficiency would affect the growth and development of
      children, so it is urgent to identify the dietary recommended nutrient intake (RNI) of iodine
      for children to guide children scientifically and safely supplement iodine. There are few
      studies about the dietary recommended nutrient intake (RNI) of iodine in children, and
      present data are old and outdated.
    

Detailed description: 
      Based on the investigators'previous study on upper safe level of iodine on children from
      areas with high iodine in drinking water, this study will conduct an epidemiological study on
      600 children living in areas with high water iodine content but the actual iodine content in
      participants' drinking water is not so high, while no supply of iodized salt.

      Meanwhile, in order to get iodine dietary recommended nutrient intake (RNI) values of
      children. The investigators will conduct a iodine balance experiment on children with
      sufficient iodine nutrition. We will randomly select thirty healthy students for a three-day
      iodine balance experiment from the cross-sectional study. The investigators will use the
      regression model to obtain an iodine intake value when children at"zero iodine"balance.
      Combine the study at population and individual level, the investigators will obtain data on
      dietary recommended nutrient intake (RNI) of iodine for Chinese children, to properly guide
      children iodine supplementation to avoid iodine deficiency, which also will provide data for
      the update of Chinese dietary reference intakes of iodine.
    

Intervention name(s): no intervention
Intervention type(s): Other
Intervention description(s): Natural exposure of iodine.
Observational model: Other
Time perspective: Cross-Sectional
Sampling method: Probability Sample
Study population: 
        7-11 years old Primary school students who in grades 2, 3, 4 and 5 are the research
        subjects.They were recruited in Shandong.
      
Biospecimen description: 
      1. Iodine nutrition survey of children was carried out in the villages and towns with low
      water iodine and no iodized salt supply. Basic information, venous blood, water samples,
      dietary information, spot urine and two 24-hour (24-h) urine were collected and thyroid
      ultrasound was performed to comprehensively assess children's thyroid function and iodine
      nutrition status. 2. An iodine balance experiment was conducted in children. All food and
      water ingested by the subjects were measured by the weighing method, and 24-h urine and feces
      were collected. Iodine intake and excretion were assessed, and saliva samples were collected
      six times a day.
    
Keywords: nutrient; public nutrition; nutrition related diseases; nutrition epidemiology