Significant opportunities to improve child health globally were provided in the second half of the 20th century. However, malnutrition remains a major problem and in many countries the situation seems to have worsened (1). In a recent report about survival rate in childhood (2), UNICEF remained that the United Nation's first Millennium Goal, was to eradicate extreme poverty and to reduce the proportion of people who suffer from hunger by half between 1990 and 2015, as measured by the percentage of children under five years of age who are underweight. The first Millennium Goal of the United Nations is to eradicate extreme poverty and to reduce the proportion of people who suffer from hunger by half between 1990 and 2015, as measured by the percentage of children under 5 y old who are underweight.
It is estimated that 146 million children under age 5 y are underweight. It was reported that undernutrition accounts for almost half of the deaths of children under 5 (3). Worldwide more than half of the underweight children reside in south Asia, primarily in India, Bangladesh and Pakistan. Similarly, the prevalence of childhood undernutrition in sub-Saharan Africa has not changed appreciably since 1990 but, with population growth, the number of underweight children has increased. Moreover, the situation has worsened during the last 20 y, especially in sub-Saharan Africa and South Asia concomitantly with the onset of HIV/AIDS (4,5). Indeed, through worsening malnutrition, this burden of disease contributes to reversal of gains made by child survival programs. Based on the same developments, it seems unlikely that the nutrition component of the UN's first Millennium Goal will be achieved by 2015.
The main problem is not necessarily a shortage of food. Micronutrient deficiencies, poor sanitation, infectious diseases, lack of exclusive breast-feeding and marginalization of females within society are also emerging as key issues. Many types of nutritional deficiencies have been shown to be detrimental to child development. Most of the existing information pertains to the possible effects of low birth weight, inadequate breast-feeding, stunting and wasting, short-term food deprivation, and micronutrient deficiencies. It is well established that deficiencies of micronutrients, such as vitamin A, increase the risk of childhood infections and subsequent mortality (6). Nutritional interventions have a major impact, as emphasized by both Allen and Bhutta in their articles in this supplement to the Journal of Pediatric Gastroenterology and Nutrition. Child nutrition programs involving vitamin A supplementation are recognized as important public health interventions among young children in areas of endemic vitamin A deficiency. Other deficiencies of micronutrients such as zinc and iron are also being recognized as widespread in developing countries and associated with increased risk of morbidity and mortality. The impact of infections on micronutrient status and their subsequent impact on health outcomes have also been established. Increased losses of micronutrients such as vitamin A and zinc during infectious illnesses, especially diarrhoea, are important contributors to micronutrient deficiencies. The role of zinc supplementation in accelerating recovery from diarrhoeal diseases in developing countries supports its use in endemic areas from the viewpoint of public health strategies (7). Furthermore, vitamin C and zinc reduce the incidence and improve the outcome of pneumonia and malaria, especially in children in developing countries (8).
It is clear that nutritional solutions for preschool children remain a challenge for the third millennium. It is well established that inappropriate feeding and infections are the main causes of protein-energy malnutrition, which contributes to morbidity and mortality in preschool children. As mentioned previously, nutritional interventions may improve infant and young child nutrition and health. This is central to human well-being and as such contributes to both economic development and poverty reduction. However, current circumstances reveal a nutritional paradox. As reported by Uauy and coworkers in Latin America and emphasized by Zlotkin in this issue, overweight and obesity are increasing rapidly in more developed areas of the world. The current system of sharing world resources has resulted in a paradigm in which the number of obese and overweight children actually surpasses the number of undernourished children globally. Improving weight gain is thus insufficient to promote child health (9). Thus, underweight, obesity and iron deficiency may coexist in the same country and even in the same household at the same time.
Nutritional rehabilitation and prevention may be achieved by carefully assessing the situation associated with an integrated combination of improved dietary intake, supplementation, commercial and home-based fortification of complementary foods. As emphasized by Mannar, several developing as well as developed countries have implemented with sustained impact successful approaches to eliminate protein-energy malnutrition and micronutrient deficiencies for nutrients including iron, iodine, selenium, zinc and vitamin A. These include provision of oral supplements in capsule, tablet or syrup form as well as fortified complementary foods provided through public feeding programs and commercially marketed foods. Mannar stresses that government commitment, clear policy and program direction, advocacy and communication combined with a strong public–private partnership are essential for successful programs to improve the health and well-being of millions of children around the world.
Importantly, during the last 3 decades the links between infant nutrition and health in adulthood have been established. Clinical and experimental data have provided evidence that the concentrations of hormones, metabolites and neurotransmitters during critical phases of early human development may have detrimental effects on brain development and metabolic processes and may cause diseases in subsequent adulthood. This phenomenon is recognized today as programming or metabolic imprinting. Interactions between the genetic background of the individuals and environmental influences during infancy and early childhood are supported by numerous experimental data (10). There is now evidence in humans that programming is 1 of the most important risk factors for obesity and cardiovascular disease (11). Barker and coworkers provided strong epidemiological evidence for a link between the quality of foetal growth as assessed by anthropometric measures at birth and morbidity and mortality during adulthood, especially in terms of high blood pressure and cardiovascular disease (12,13). In addition, Barker et al. provided evidence for a strong link between the rate of postnatal catch-up growth and the onset of metabolic and cardiovascular diseases in adulthood (14).
Establishing the links between nutrition and brain development is challenging. However, there is increasing evidence that protein-energy malnutrition has deleterious effects on learning and cognition (15). Many studies have suggested or even demonstrated that these effects are dependent not only upon the type of nutrients involved (eg, iron, iodine, selenium, zinc, vitamin A, essential fatty acids) but also upon the specific periods of development including prenatal life, infancy, school age and aging. The postinfancy or preschool age is a period in which a number of nutritional deficiencies have been shown to interfere with normal development and cognition (16). The most commonly studied deficiencies in children with protein-energy malnutrition are iodine, iron and essential fatty acids deficiencies. Yehuda and coworkers provide in this issue a short review that aims to examine the limited studies that have been performed on children of this age and offer a broader view on this topic. Finally, previous experience as well as more recent knowledge establishes the link between early nutrition and health, not only in childhood but also in adulthood. Nutrition during pregnancy as well as feeding during infancy and young childhood remain crucial issues for humanity, whether in developing or developed countries.
Assessing the nutritional status of populations, improving research and knowledge in the field of nutrition and increasing food resources by developing agriculture and economies exist as the challenges of this century and beyond. Globally malnutrition, whether intrauterine growth retardation, vitamin or micronutrient deficiency, inappropriate protein and/or energy supply, persist as significant causes of disability, with young children the worst affected.
As emphasized by Darnton-Hill in this supplement, improved health and nutrition will lead to enhanced economic development, but having a poverty focus appears to be essential if poor people are not to be marginalized further. The HIV/AIDS pandemic illustrates this challenge clearly. The role of education, especially girls' education, in improved health and nutrition status of children and in birth spacing, is now clear, as is improving women's status. Increases in female status and education have been estimated to account for half of the reduction in child malnutrition rates during the past 25 y.
Thus, it was logical to devote a symposium to how to adequately feed preschool-age children and to overcome the double burden of malnutrition: undernutrition and obesity. This supplement of the Journal of Pediatric Gastroenterology and Nutrition reports the proceedings of the 2005 symposium on nutritional solutions to major public health problems of preschool children, organized by Danone Institute International in Durban, South Africa, on the occasion of the 18th International Congress of Nutrition. This collection of presented papers offers a unique opportunity to report the outstanding work of well-known international experts in the field. It is critical to promote the right of all of the world's children to achieve their full genetic growth potential and to guard against the side effects of an inadequate nutritional supply, whether caused by under- or overnutrition.
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