The impact of iron fortification on nutritional anaemia
Sean R. Lynch MD, Professor of Clinical Medicine
Department of Internal Medicine, Eastern Virginia Medical School, Norfolk, VA, USA
Iron deficiency continues to be the most prevalent nutritional deficiency disorder in the world, affecting an estimated two billion people, most of whom live in developing countries. It has far-reaching effects on the health, well-being and productivity of those affected. Iron fortification of food is regarded as the most cost-effective method for reducing the prevalence of nutritional iron deficiency. In industrialized countries this has had an important beneficial effect; however, nutritional anaemia remains very prevalent in developing countries, and iron fortification appears until recently to have had little impact. Two important reasons for the latter situation are inadequate documentation of the magnitude of the iron deficiency component of anaemia in different regions of the world, and the use of iron compounds that are poorly bioavailable in fortification programmes. Several recent interventions using innovative approaches to dietary fortification that ensure the delivery of adequate quantities of bioavailable iron have demonstrated that iron fortification of food can be an effective and implementable strategy for controlling nutritional iron deficiency in non-industrialized countries.
Strategies for controlling nutritional iron deficiency
Impact of iron fortification on the reported prevalence of iron deficiency in industrialized countries
Specific evidence for an impact of mass fortification on prevalence of iron deficiency
Impact of fortification on the reported prevalence of iron deficiency in non-industrialized countries
Laboratory methods for documenting the prevalence of iron deficiency
Fortification methods
Successful fortification strategies in developing countries
Targeted fortification
Mass fortification
Potential risks of iron fortification
Summary and conclusions
In the World Health Report 2002 (‘Reducing Risks, Promoting Healthy Life’) nutritional iron deficiency was identified as one of the 10 leading risk factors for disease, disability and death in the world today, with an impact greater than that of either zinc or vitamin A deficiency. An estimated two billion people are affected, most of whom live in developing countries.
Adequate iron nutrition is assured only when the diet contains sufficient bioavailable iron to meet the requirements for growth and pregnancy, and to replace iron lost through menstruation, from the gastrointestinal tract and skin, and in the urine. Iron is present in most foods, and its intake is directly related to energy consumption. The risk for nutritional iron deficiency is therefore greatest when iron requirements are proportionately greater than energy needs in early childhood, at the time of the adolescent growth spurt, in women of childbearing age and during pregnancy.
Iron deficiency has a significant impact on the well-being of individuals as well as the productivity of societies. Pregnancy outcome is suboptimal, with increased risks for mothers and their babies including lower birth weight, increased infant mortality, and a greater risk for iron deficiency after the first 4 months of age. The mental and motor development of very young children may be delayed, with effects on behaviour and later academic performance during the school years. Failure to meet educational goals is likely to have a negative impact on earning power in adulthood. Physical work capacity is impaired at all ages. There are significant economic consequences for the individual, the family and the country, particularly where people's livelihoods depend on manual labour. Upper respiratory infections are more frequent and last longer in iron-deficient children. Finally, the response of endemic goitre to iodine supplementation may be suboptimal in populations that suffer from deficiencies of both iodine and iron.
The adverse effects of iron deficiency result from both impaired oxygen transport because of anaemia and the consequences of tissue iron deficiency that influences aerobic metabolism, protein synthesis, receptor function and many other metabolic processes. Tissue iron deficiency and anaemia become manifest simultaneously. There is a growing body of experimental evidence indicating that the effect of iron deficiency on psychomotor development in infancy results from the tissue iron deficit in the brain rather than the accompanying anaemia. Nevertheless, an effect of iron deficiency without anaemia on cognitive and motor development has not been established. On the other hand physical performance may be affected by iron deficiency in the absence of anaemia.
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