Using standardized methods, the investigators will perform stable iron isotope absorption studies in young Kenyan women and their preschool children (2-5y of age) with varying iron status to measure iron absorption from maize meal containing labeled ferrous sulfate. Using these data, this study aim is to define the ferritin in these young women and children at which the body senses iron depletion and begins to upregulate iron absorption from the diet; this approach could provide a functionally defined threshold of iron deficiency in Sub-Saharan African women and children.

In this experimental study in southern Kenya, the investigators will take a baseline venous blood sample to measure iron and inflammation biomarkers in generally healthy young women (n=125) and in their preschool children. The investigators will then administer, after an overnight fast, a standardized test meal porridge made from refined maize and bottled water containing the stable iron isotope 57Fe. Fourteen days later, the investigators will take a second venous blood sample for determination of erythrocyte incorporation of the 57Fe to measure iron absorption from the labeled test meal.

Inclusion Criteria:

• < 75 kg
• BMI between 17 - 27.5 kg/m2
• No acute illness (self-reported)
• No metabolic or gastrointestinal disorders (self-reported)
• No use of medication affecting iron absorption or metabolism during the study
• No intake of mineral/vitamin supplements 2 weeks prior to the first study visit and during study
• Mother of a preschool age child (2-5 years)
• Child has normal Z-scores for WAZ, HAZ and WHZ (-3 - +3)