Safety of Interventions to Reduce Nutritional Anemia

Iron deficiency is estimated to cause more ill health and disability worldwide than any other nutrient deficiency. This underpins a public health drive to combat iron deficiency by interventions on multiple fronts. Many interventions such as increasing dietary diversity, introducing biofortified crops, or improving sanitation and hygiene have no safety concerns, but can have limited efficacy. Direct supplementation with iron in the form of tablets, syrups, or point-of-use micronutrient powders has greater efficacy, but has been associated with a range of adverse outcomes especially in the settings of poverty and poor hygiene where they are most needed. These adverse outcomes result from a battle for iron between humans and micro-organisms in which iron can enhance the virulence of numerous human pathogens. This chapter provides a high-level review of the existing evidence that iron interventions increase the likelihood of serious infections by bacteria, protozoa, viruses, or fungi, and whether they cause adverse perturbations of the gut microflora. We conclude that the evidence for possible harm is real, but that there are ways to ameliorate the risks, and that the benefits of iron interventions will generally outweigh any risks.