A Novel Stable Iron Isotope Method to Define Iron Needs and Improve Iron Nutrition in HIV+ and HIV- Children

In Sub-Saharan Africa, HIV is a major cause of morbidity and mortality in children. Anemia frequently complicates pediatric HIV infection and predicts disease progression and mortality. Iron requirements and the specific contribution of iron deficiency (ID) to anemia in pediatric HIV infection remains uncertain. The fundamental barrier to understanding iron nutrition in HIV infection is that sub-clinical inflammation in individuals with HIV infection confounds the usual bio-markers used to assess iron status and response to iron interventions. A novel iron stable isotope technique developed by ETH Zurich, Switzerland, is a promising new tool for better understanding of iron metabolism in HIV infection. In contrast to existing conventional bio-markers of iron status, a method based on isotopic dilution of whole body iron labeled with stable, non-radioactive isotopes of iron (58Fe, 57Fe) could directly quantify iron requirements, as well as iron absorption from interventions, completely free of bias and confounding by inflammation. This method could offer, for the first time, a long-term quantitative measure of iron balance and absorption from iron interventions and provide reliable data on which to base nutrition recommendations for HIV infection.

The objective is to compare HIV infected children to uninfected children: 1) Quantify iron absorption from iron fortified maize porridge, lipid-based food supplements and oral iron supplements; 2) Quantify the daily iron requirement.

The study participants will be recruited from the South African Stellenbosch University/Tygerberg Children's Hospital long-term antiretroviral therapy (ART) cohort of perinatally HIV infected children and uninfected controls from the same communities, matched by age and gender. As a secondary outcome, we want to investigate the effect of iron supplementation on the gut microbiome.

In study 1, using a randomized cross-over design and stable isotope labeled single meal/doses the investigators will: a) quantify the impairment of dietary iron absorption in HIV infected, iron deficient children compared to HIV uninfected, iron deficient controls using a labeled iron fortified maize meal, a lipid-based nutritional supplement (LNS) and an oral iron supplement; and b) administer sufficient iron isotope label (57Fe) to allow equilibration and follow up of isotopic composition in the blood for two years (isotope dilution technique). At the end of Study 1, all iron deficient children will be iron replete prior to entering Study 2. In study 1, in parallel, a group of HIV infected and uninfected, iron sufficient children will be given orally 12 mg 57Fe as ferrous sulfate (FeSO4).

In study 2, the investigators will apply the principle of long-term isotope dilution to quantify the daily iron requirement in both the HIV infected and uninfected children, and the difference in iron requirements.