The investigators will evaluate these forms of iron using a randomized clinical trial approach that will robustly test the formal hypotheses and yield useful answers to the primary questions about the relative safety and efficacy of these novel forms of iron in iron-replete subjects. This study is divided to two phases. In Phase I, the investigators will determine of effects of form of low-dose, supplemental iron. Three forms of iron administered at the dose of 60 mg Fe/d will be evaluated against the primary outcomes of ex vivo malarial infectivity, bacterial proliferation potential (also assessed ex vivo) and gut inflammation, and other relevant outcomes in adults. In this protocol the investigators refer to this set of indicators as the "safety profile". The justification for providing 60 mg Fe/d is based on the World Health Organization (WHO) recommendation for daily supplementation for non-anemic, pregnant women with 30-60 mg Fe/d. In addition, the effects on those outcomes of ferrous sulfate administered daily (60 mg Fe/d) vs. weekly (420 mg Fe administered in one weekly dose) will be compared. There is great practical value in addressing this hypothesis of whether a weekly dose can be administered without adverse effects. Nested within this design will be a second comparative study of effects in iron-replete children and adults to validate the applicability of data obtained in adults to children.