The economics of iron deficiency
Introduction
Iron deficiency has earned distinction as the most common nutritional deficiency in the world today. Because iron is important for blood formation, iron deficiency often leads to anemia, defined as having a blood hemoglobin level below standard.1 It is estimated that 1.7 bn people worldwide suffer from anemia, of which half is iron-deficiency anemia (IDA) (WHO, 1997), while iron deficiency (without anemia) is as widespread as IDA. Given the magnitude of the problem it is important to know how IDA actually affects the lives of these individuals. Many studies document the association of IDA with poor pregnancy outcome, poor motor and mental performance in children and low work productivity in adults. Studies also increasingly show that milder iron deficiency, unaccompanied by anemia, has negative outcomes.
This paper aims to make realistic quantitative estimates of the economic consequences of iron deficiency that can be defended on epidemiologic and economic grounds, and to use these to estimate population-wide benefit–cost ratios for iron fortification.
There are two broad areas in which iron deficiency is considered to have important functional impacts on humans, where economic consequences can be estimated: cognitive ability of children, and work capacity of adults. Although we also examined child growth, immune function and susceptibility to the toxic effects of heavy metals , there was insufficient consistent evidence to incorporate these into the analysis. Effects on pregnancy outcome are well documented, but insufficient cost data exist for developing countries to incorporate this into the economic analysis.
Our benefit–cost ratios can be compared to the few previous such estimates. Levin et al. (1994) using hypothetical data estimate this ratio as 84:1 for iron fortification interventions, and 28:1 for iron supplementation (with corresponding ratios ranging from 6:1 to 28:1 for iodine interventions, and 7:1 to 22:1 for vitamin A interventions). The present study benefits from more recent literature on the functional consequences of iron deficiency to refine previous estimates. We also allow for different consequences in light manual work, and heavy manual work, and include the cognitive effects on white-collar work, not previously considered.
Section 2 considers effects on children and Section 3 on adults. Section 4 estimates the costs of iron deficiency anemia for a selection of 10 countries, and uses the first effectiveness data available for a national iron fortification program in a developing country (Venezuela) as a guideline to simulate cost–benefit ratios for national iron fortification programs in 10 selected countries. Section 5 concludes.
Section snippets
A biological mechanism
The biological basis for the effects of iron uses animal studies. There are high concentrations of iron in certain similar regions of both the rat and human brains, suggesting important roles for iron that could account for its importance in cognition. Evidence from iron-deficient rats suggests a permanent reduction in dopaminergic neurotransmission due to the failure to develop dopamine receptors early in life (Ben-Shachar et al., 1986, Yehuda et al., 1986). Dopamine is an important
Evidence of effects of iron deficiency/anemia
It has long been observed that the symptoms of iron deficiency anemia include tiredness, lethargy and fatigue. The biological basis for these effects almost certainly includes the role of hemoglobin as an iron-containing transport protein needed to move oxygen from the lungs to the muscles, brain and other tissues of the body. Anemic individuals are therefore unable to transport enough oxygen to support strenuous activity of long duration. It is likely that iron deficiency affects several other
Country examples
Table 4 contains some results of calculations of the labor productivity effects (using the methodology described in 2 Lower future productivity of children, 3 Lower current productivity of adults) for ten selected countries.4 Some of the
Conclusions
We have tried to calculate and substantiate some of the economic losses due to iron deficiency. These include the cognitive losses due to childhood iron deficiency (Section 2), and the loss due to lower productivity in manual occupations for adults (Section 3). The cognitive losses are large and increase faster with development, although these losses have been less widely recognized in previous literature. We do not attempt to estimate the economic costs associated with the social cost of the
Acknowledgements
The authors would like to thank the Micronutrient Initiative who commissioned the original technical paper on which this paper is based, in particular Jenny Cervinskas who commissioned the study and Janice Johnston who coordinated the review process. Thanks also for very helpful comments on various drafts of the technical paper to George Beaton, Jere Behrman, Alan Berg, Jere Haas, Janice Johnston, Henry M. Levin, Venkatesh Mannar, Ernesto Pollitt and two anonymous referees. The initial work was
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