Participating children are screened for EED using the lactulose:mannitol ratio test and assigned to one of two groups: +EED or -EED. All participants will be given standard, physiological dose of 3 mg zinc sulfate with a zinc stable isotope tracer on study day 8.
On study day 11, 0.5 mg of 13C10-retinyl-acetate will be administered orally to all participants.
Spot urine samples will be collected twice daily from study days 11-14. Complete fecal collections will be obtained for days 11-14. Duplicate diets of all foods consumed will be collected on days 11-14. On study day 14, a blood sample will be taken for analysis of vitamin A isotope status.
