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Undernutrition causing 3.5m deaths annually

Undernutrition includes both protein-energy malnutrition and deficiencies of micronutrients, such as essential vitamins and minerals (1). This article provides an overview of the current status of under-nutrition in Bangladesh. Under-nutrition is the underlying cause of 3.5 million deaths worldwide, and accounts for 35% of the disease burden in children under five (2). Child and maternal under-nutrition seriously challenge progress towards national and international economic, health and development goals, including the Millennium Development Goals (3). The consequences of under-nutrition are serious, long-term, intergenerational and mostly irrevocable, resulting in increased morbidity and mortality, increased disease burden, and decreased IQ, physical capacity, and productivity. All of these have negative effects on income and economic growth of the country (3). Of the total global disability-adjusted life years (DALYs), 11% are lost due to child malnutrition (2). Measures of under-nutrition There are three commonly used indicators to assess growth faltering in children. These include height-for-age, weight-for-height and weight-forage. Deficits in these three indicators reflect a distinct process or outcome of growth impairment. Low height-for-age, commonly known as stunting, or chronic malnutrition, reflects a process of failure to reach linear growth potentials as a result of sub-optimal health or nutritional conditions. In younger children, aged 2 to 3 years, it reflects an ongoing process of 'failing to grow', whereas in older children it reflects the state of 'having failed to grow' or being 'stunted'. Low weight-for-height, commonly known as wasting or acute malnutrition, measures thinness and indicates a recent event of weight loss that is often associated with acute disease conditions or starvation. A prevalence between 10%-14% is regarded as serious and above 15% it is critical, warranting public health interventions (4). Low weight-for-age, or underweight, measures body mass relative to chronological age. It is influenced by both the child's height (height-for-age) and weight (weight-for-height). Thus weight-for-age fails to identify whether a child who is underweight is stunted, wasted or both. In children >3, low weight-for-age is primarily caused by stunting in most lowincome countries, although in famine situations low weight-for-age usually represents wasting (5). Under-nutrition has been and continues to be a serious public health problem in Bangladesh (6). The prevalence of underweight children, defined as weight-for-age <-2 Z-score among children <5, was more than 65% in 1989-1990 (7) (Figure 2). Although it decreased to 47% in 2000, there has been little change since then. The most recent national nutrition survey shows that the prevalence of underweight children <5 is 41% (6). About 43% of children <5 are stunted (height-for-age <-2 Z-score). Wasting is present in 17% of children <5, with 3.4% of children <5 being severely wasted (6,8). This accounts for more than 0.5 million children with severe acute malnutrition in the country. Furthermore, rates of low birth weight among Bangladeshi infants, although reduced from 40%, are still among the highest in the world, ranging from 20-22% (9-11). These children are at risk of death or severe impairment of growth and development. Micronutrient Deficiencies Micronutrient malnutrition is often termed as 'hidden hunger' as the consequences are not always visible. There are four micronutrients that are of particular relevance to public health: vitamin A, iron, iodine and zinc. Vitamin A deficiency disorders include the specific ocular manifestations of xerophthalmia and its blinding sequelae (which encompass - night blindness, bitot's spot, corneal xerosis and xerophthalmia) as well as nonspecific consequences such as anaemia, immune dysfunction, and increased susceptibility to infection, poor growth, and mortality (5). In Bangladesh, there has been a dramatic reduction in prevalence of night blindness among preschool children from the 1980s to 2004, which is attributed to the successful vitamin A supplementation programme launched in 1973 (12-15) with an impressive coverage of 88% (6). Post-partum vitamin A supplementation coverage for mothers, however, is very low at only 20% (6). Iron deficiency is one of the most common nutrition disorders worldwide. Anaemia is the most commonly used indicator to define iron deficiency in population-based studies or in clinical settings, although anaemia in itself is not specific for iron deficiency. It is generally assumed that 50% of the cases of anaemia are due to iron deficiency (16). However acute and chronic infections, including malaria, cancer, tuberculosis, and HIV can also lower blood haemoglobin concentrations (16). Surveys conducted in 2003-2004 show that 92% of infants aged 6 to 11 months old in Bangladesh suffered from anaemia and that the prevalence of anaemia increased from 2001 to 2004 (17). During that time, the prevalence of anaemia in pre-school children was 68%, in adolescent girls it was 40%, and four out of 10 pregnant women suffered from anaemia, particularly in rural areas (17). An estimated 7.9% of the gross domestic product in Bangladesh was lost due to anaemia (17). In 1993, the goiter prevalence in Bangladesh was 47%, cretinism 0.5% and sub-clinical iodine deficiency (low urinary concentration of iodine, <100µg/L) was 69% (18). A survey in 2004-2005 showed an improvement in iodine deficiency with the prevalence of goiter among children 6 to 12 years old of 6.2% and among women 15 to 44 years old of 11.7% (19). However, more than one-third of children and women still had sub-clinical iodine deficiency (19). Zinc is essential for human health due to its critical structural and functional roles in multiple enzyme systems that are involved in gene expression, cell division, growth, and immunologic and reproductive functions. At the population level th