This study will assess total body vitamin A pool size, as well as liver vitamin A stores, by means of stable isotope dilution in preschool children from a South African community where liver, an exceptionally rich source of vitamin A, is frequently eaten, and the children exposed to vitamin A fortified staple foods, as well as a vitamin A supplementation programme.

Serum retinol, the most commonly used indicator to assess vitamin A status, is homeostatically controlled and, although it is able to detect deficiency, it does not necessarily reflect liver stores or measure excessive vitamin A intake. The stable isotope dilution method is able to measure total vitamin A body pool size over the vitamin A status continuum, including the sub-toxic range,and would add valuable information about the vitamin A status in a community where liver (an exceptionally rich source of vitamin A) is frequently eaten, and children also exposed to other vitamin A interventions. Total body vitamin A will be assessed before and 4 weeks after a high dose vitamin A supplement given to the children as part of the national vitamin A supplementation program. The confounding effect of infection/inflammation on the biomarkers of vitamin A status will also be examined, as well as how serum retinol and retinol binding protein relate to each other, and to vitamin A pool size.

Inclusion Criteria:

• Living in the study area;
• Must not have received a vitamin A supplement in the preceding month

Exclusion Criteria:

• Severe anaemia (haemoglobin < 9 g/dL);
• Fever (body temperature > 38°C)

3-5 year-old children from a low socio-economic South African community where liver is frequently eaten