The overall objective of this study is to determine dietary iron absorption from lipid-based nutrient supplements (LNS) in apparently healthy and undernourished children. This case-control study will recruit apparently healthy children and children with uncomplicated undernutrition (age 1-3 years, n=15/group) from Msambweni and the surrounding rural communities in Kwale County, Kenya. At the baseline visit (day 0), participants will be provided with an LNS labeled with a stable iron isotope (57-Fe). Participants will return to the hospital 14 days later (day 14) for a blood draw. Blood collected on day 14 will be used to measure iron isotope incorporation into red blood cells. Blood collected at screening will be used to measure indicators of anemia, iron status, hepcidin, and inflammation.

Inclusion Criteria:

• Children age 1-3 years on day of screening visit
• Hemoglobin 8-11 g/dL on day of screening visit
• Undernourished [length/height-for-age z-score (HAZ), weight-for-age z-score (WAZ), and/or weight-for-height/length z-score (WHZ) < -2] OR apparently healthy (HAZ, WAZ, and/or WHZ ≥ -1)

Exclusion Criteria:

• Severe acute malnutrition (WHZ < -3) with no appetite
• Serious medical condition or other chronic disease besides undernutrition (e.g., HIV+, severe pneumonia, malaria)
• Peanut allergy or other allergy that prevents consumption of the LNS
• Plans to move away from the study location during the study period

Participants will be recruited from Msambweni and the surrounding rural communities in Kwale County, Kenya.