Using selective plant breeding and genetic engineering could be used to reduce the incidence of iron deficiency worldwide by improving the quality of dietary iron, conclude authors of a Seminar in this week’s edition of The Lancet.
Dr Michael Zimmerman, Laboratory for Human Nutrition, Swiss Federal Institute of Technology, Zurich, and colleagues have reviewed published literature worldwide, mainly from the last five years, to prepare the Seminar, which looks at the issue of nutritional iron deficiency in both industrialised and developing countries.
The authors say: “Iron deficiency is one of the leading risk factors for disability and death worldwide, affecting an estimated 2 billion people…the high prevalence of iron deficiency in the developing world has substantial health and economic costs, including poor pregnancy outcome, impaired school performance, and decreased productivity.”
The World Health Organisation (WHO) estimates that 39% of children younger than five years, 48% of children between five and 14 years, 42% of all women, and 52% of pregnant women in developing countries are anaemic, with half having iron deficiency anaemia. WHO also believes that the frequency of iron deficiency in developing countries is around 2.5 times that of anaemia which is not iron deficiency related.
Dietary iron bioavailability (the measure of iron which can be absorbed from food) is low in populations consuming monotonous plant-based diets with little meat – ie. many developing countries. In an analysis of ten developing countries, the median value of physical productivity losses per year due to iron deficiency was around US $0.32 per head, or 0.57% of gross domestic product (GDP) for those nations. In the WHO Africa subregion, it is estimated that if iron fortification reached 50% of the population, it would avert 570,000 disability adjusted life years (DALYs- an international standard for measuring the effects of disability).
Iron deficiency has many reported consequences – children deficient in iron have higher susceptibility to upper respiratory tract infections, and anaemia which can affect their brain, motor activity and general performance in school, whilst adult manual laborers in developing countries were found to be less productive when iron-deficient, and left untreated for hookworm and other infections.
The three main strategies for correcting iron deficiency are supplementation (provision of iron without food), fortification of foods, and the relatively new approach of genetic engineering and plant breeding. The authors say: “Although dietary modification and diversification is the most sustainable approach, change of dietary practices and preferences is difficult, and foods that provide highly bioavailable iron (such as meat) are expensive.”
Supplementation can be targeted to high risk groups and be cost-effective; yet the logistics of distribution and absence of compliance are major limitations. Untargeted supplementation in children in tropical countries, mainly in areas of high transmission of malaria, is associated with increased infections.