Iron: Current Landscape and Efforts to Address a Complex Issue in a Complex World

Abstract

N utritional iron deficiency is the leading nutrient deficiency worldwide affecting more than 1 billion people, predominantly women, infants, and young children. The consequences of iron deficiency are significant for shortand longterm health, economic growth, and development. The question of how to best identify those at risk, as well as how to monitor the success of interventions in patients and populations, is complicated by a number of factors that include a complex biology and homeostatic controls that can compromise the safety and efficacy of interventions to address this global scourge. The complexity of this situation is exemplified by the reciprocal relationships between iron and the inflammatory response under a variety of developmental and health conditions. Not only does iron play an integral role in the function of the immune system and key elements of the inflammatory response, the converse is also true. This complex interrelationship is graphically manifested in the area of iron assessment as the performance and interpretation of the most common biomarkers used for iron assessment are affected by the presence of inflammation. Inflammation can be acute (because of infection) or chronic (because of obesity or a myriad of noncommunicable diseases). In effect, the inflammatory response causes the body to mobilize iron out of the peripheral circulation and reduces its ability to absorb iron from the diet. This physiological response then causes changes in the concentrations of biomarkers that reflect changes in iron physiology rather than changes in nutrition. Thus, one might interpret such results as reflecting a nutritional “deficiency” that is in fact a response to an infection and inflammation rather than a decrease in iron consumption. The dilemma this presents is that if someone actually is not nutritionally deficient and receives iron, it may not be safe. The details of this challenge, clinically and programmatically, are the focus of a series of activities that will be summarized.