Using Stable Isotope Techniques to Monitor & Assess the Vitamin A Status of Children Susceptible to Infection

The relationship between infections and malnutrition is synergistic, each further compromising the outcome of the other. Malnutrition compromises natural immunity leading to increased susceptibility to infections, more frequent and prolonged disease episodes, and increased severity of disease. Likewise, infections can aggravate or precipitate malnutrition through decreased appetite and food intake, nutrient malabsorption, nutrient loss or increased metabolic needs. Severe malnutrition often masks symptoms and signs of infectious diseases making prompt clinical diagnosis and treatment very difficult. Another issue is that infections (as well as overweight and obesity status) affect nutritional biomarkers making it difficult to assess the real magnitude of some nutritional problems. This is the case of vitamin A. Vitamin A deficiency is defined to be of severe public health importance if 20% or more of a defined population has a serum retinol concentration of less than 0.7 µmol/L.