The goal of this study is to assess whether children 12-18 months of age who are exposed to multiple large-scale vitamin A programs, and who are likely to have vitamin A intakes above the tolerable upper intake level (UL), have higher total body vitamin A stores and biomarkers of excessive vitamin A status, compared to children 12-18 months of age who have adequate vitamin A intake.

This is an observational study with 3 groups, which are identified using a screening tool to obtain information on exposure to vitamin A programs and consumption of vitamin A-rich foods and supplements. Children and their mothers are studied over the course of one month to determine 1) child total body vitamin A stores, using the 13C retinol isotope dilution method, 2) the child's vitamin A intake, using multiple dietary assessment methods, 3) total breast milk intake (among breastfeeding children), using the dose-to-mother deuterium dilution method, and 4) potential biomarkers of excessive vitamin A status, including markers of bone and liver health. Blood collection is structured in a "Super-Child" design, to construct plasma retinol kinetic curves. Other indicators related to vitamin A nutrition among children will be measured, in addition to the vitamin A intake and breast milk vitamin A concentration (for breastfeeding mothers) of the mother.

Inclusion Criteria:

• Children 12-18 months of age, and their mothers (18-49 years of age)
• Living in selected communities in the National Capital Region of the Philippines
• The mother and child must plan to stay in the study area for the duration of the study.
• Child's estimated vitamin A intake and exposure to vitamin A programs must meet eligibility criteria for one of three groups, based on a screening questionnaire administered by an interviewer to the child's mother.

Eligibility criteria for children in Group 1: 1) consumed MNP or a multi-vitamin preparation that contains vitamin A in the previous 7 days, 2) consumed at least one fortified staple food (oil or wheat flour) in the previous 7 days, 3) consumed breast milk or fortified milk in the past 24 hours, 4) received a high-dose VA capsule during the previous month, and 5) received a screening tool 'score' suggesting VA intake above 600 µg retinol/d.

Eligibility criteria for children in Group 2: will include children who: 1) consumed MNP or a multi-vitamin A preparation that contains vitamin A in the previous 7 days, 2) consumed at least one fortified staple food (oil or wheat flour) in the previous 7 days, 3) consumed breast milk or fortified milk in the past 24 hours, 4) received a high-dose VA capsule in the previous 3-6 months, and 5) received a screening tool 'score' suggesting VA intake above 600 µg retinol/d.

Eligibility criteria for children in Group 3: will include children who: 1) received a high dose VA capsule during the previous 3-6 months, and 2) received a screening tool 'score' suggesting VA intake 200-500 µg/d.

Exclusion Criteria:

• The child did not receive a high-dose VA capsule during the most recent national campaign
• The mother or child has chronic disease
• The child has moderate or severe anemia (Hb <10 g/dL)
• The mother or child has signs or symptoms of vitamin A deficiency (Bitot's spots, conjunctival xerosis, nightblindness)
• The child has weight for length < -2 z-scores of the median of the WHO growth standards
• The mother is breastfeeding more than one child

Children 12-18 months of age and their mothers in selected neighborhoods in the National Capital Region of the Philippines

To be determined.