Iron Absorption in Vegetarian Children
Condition: Iron Absorption
Study type: Observational

Summary: 
      Few areas are more controversial in pediatric nutrition than the role of a vegetarian diet
      for children. Advocates make strong health claims whereas others have expressed safety
      concerns, especially regarding iron nutrition. The frequency of vegetarianism among children
      is said to be rapidly increasing although clear data are not available. Surveys of children
      in the US age 8 to 18 reported in the media find that about 3-5% of children are lacto-ovo
      vegetarian, with some fish or chicken products in the diet. This is a substantial proportion
      that is very likely to increase over the next few years with essentially no nutrient
      metabolism data related to this population.

      One of the principal concerns with a lacto-ovo vegetarian diet, as preferred by many
      children, is the lack of heme iron in the diet. A key question that can be evaluated in
      children is whether iron status is in fact affected by a lacto-ovo vegetarian diet.

      According to the American Academy of Pediatrics (AAP Pediatric Nutrition Handbook, 6th
      Edition, 2008), vegetarian diets can provide appropriate nutrition for children. Depending on
      the level of dietary restriction, fortified foods or supplements may be necessary during
      different life stages. In addition, strict vegetarian children may have slightly higher
      protein needs compared to non-vegetarian children due to decreased protein digestibility in
      certain plants. The AAP further recommends that children 4-8 years old consume a minimum of
      five servings per day of beans/nuts/seeds/eggs and six servings per day of calcium-rich
      foods.

      To evaluate this issue, the investigators will use a stable isotope method to directly assess
      iron status. It is increasingly recognized that the ability to absorb iron when given with
      vitamin C is a highly accurate measurement of iron status and may be a true gold standard in
      this regard. In this planned study, investigators will be able to assess both reference dose
      iron absorption and standard biochemical markers of iron status in a group of lacto-ovo
      vegetarians and compare them with age- and gender-matched children on a non-vegetarian diet.
      These data can be important in determining if iron status is decreased in lacto-ovo
      vegetarians and will serve as a basis for future interventions and evaluations if a
      difference is found.
    

Detailed description: 
      Iron absorption studies will be done in 30 healthy vegetarian children 4 to 10 yrs of age and
      30 healthy non-vegetarian children who are age and gender matched controls (from another
      study).

      Visit 1: At the time of enrollment, subjects and their families will be asked to come to the
      General Clinical Research Center (GCRC) of Texas Children's Hospital or the Metabolic
      Research Unit (MRU) at the Children's Nutrition Research Center for a screening visit. Prior
      to this visit, demographics from the parent/guardian will be recorded including the child's
      approximate height and weight, and the study dietitian will obtain two 24-hour dietary
      recalls from the parent to determine dietary intake for enrollment. During this screening
      visit, informed written consent will be obtained and anthropometry and vital signs will be
      recorded.

      The study dietitian will instruct the parent/guardian and child on the use of a food scale to
      weigh and record dietary intake for a 3-day period (ie, 3-day weighed diet record). The 3-day
      weighed diet record will begin the following day. Upon analysis of their child's intake,
      parents will be instructed to maintain a similar nutrient intake throughout the study.
      Compliance will be monitored via 3-day weighed home diet records timed with their other study
      visits. If analysis shows that the child's intake has significantly changed (± 20% of a
      nutrient), the parent will be counseled by the study dietitian on readjusting the child's
      intake back to the usual level determined at baseline.

      Visit 2: Subjects will be admitted to the GCRC or MRU as an outpatient after a 2-3h fast and
      given a reference dose of 1mg iron-58 sulfate as an aqueous solution with 50mg ascorbic acid.
      They will be observed for 2h after this dose and water will be freely available. No food will
      be allowed however water is allowed. After 2h subjects will be discharged home and food
      allowed. After discharge, subjects will record dietary intake using another 3-day weighed
      diet record.

      Visit 3: Prior to this visit, subjects will receive a food scale and will perform another
      3-day weighed diet record to demonstrate consistency of diet throughout the study period. Two
      weeks (+/- 3 days) later subjects will be readmitted and 10mL blood (2 tsp) will be drawn for
      measurement of iron nutritional parameters (e.g. hepcidin, ferritin, iron, TIBC, transferrin
      saturation, hemoglobin, hematocrit, and RBC indices) and iron isotope ratio measurement. Labs
      for iron nutritional parameters may be sent to the TCH Lab or an outside commercial lab.
      Incorporation of iron-58 will be used to measure absorption from the reference dose (a
      measure of iron status). Topical numbing cream or spray to minimize pain at the injection
      site will be offered to all subjects.
    

Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Community sample
      
Keywords: vegetarian; children; iron; iron absorption