Controlling Micronutrient Deficiencies in Asia

Vitamin A deficiency (VAD), iodine deficiency disorders (IDDs), and iron deficiency anemia (IDA) affect large numbers of the populations in Asia, often overlapping. Clinical VAD is probably declining, but subclinical VAD is common and carries significant mortality risk. IDDs fall when there are effective iodized salt programs. IDA persists unchanged at high levels, particularly affecting women and children. Deficiency control programs—notably high-dose vitamin A capsules sixmonthly for children and iodized salt—are under way in many areas, and need to be sustained and made universal. Fortification is a key long-run solution, and multiple fortification and supplementation need to be researched and implemented. Better information is needed on programs and their impact; even baseline data are scarce. Public–private coalitions should be fostered with the food industry and others concerned. Capacity-building for the range of actions for controlling deficiencies should be an early next priority. Current Deficiencies and Control Programs icronutrient deficiencies affect a majority of the population in the eight Asian countries covered by the ADB-UNICEF Regional Technical Assistance Project on Reducing Child Malnutrition in Eight Asian Countries (hereafter referred to as the Project). Usually several deficiencies are present at a time. Iron and iodine deficiencies are the most common currently known. About half the reproductive age women in most of the countries have iron deficiency anemia (IDA), and preschool children and other groups are extensively involved. Iodine deficiency disorders (IDDs, assessed as goiter in schoolage children) strike from 20-60 percent of the population in different areas. Vitamin A deficiency has been widely recorded, although with much lower clinical prevaM Controlling Micronutrient Deficiencies in Asia 67 lences (around 1 percent in preschool children). However, serum retinol assays indicate that the subclinical prevalence, associated with increased mortality risk in children and pregnant women, may be around 10-25 percent. Other deficiencies are certainly widespread but far less well described. Rickets in young children, associated with calcium and vitamin D deficiencies, is probably widespread in the PRC and possibly elsewhere. Indirect evidence points to zinc deficiency as common. Selenium and a number of other micronutrients with effects on chronic disease (e.g., cancers) are emerging as problem areas. A brief review follows of the current situation, much of which draws on the country reports, summarized in Mason, Hunt et al. (2001). The consequences of micronutrient deficiencies can be devastating, and not only when they are clinically apparent. Iodine deficiency is the commonest cause of mental retardation (and is completely preventable), and has other far-reaching effects on cognitive and neuromotor function, reproduction, and on the development of the individual and of society (WHO 1993, Stanbury 1998). Vitamin A deficiency not only causes blindness (which is relatively rare today), but more importantly subclinical deficiency appears to be a major risk factor for both child and maternal mortality. The reduction in mortality from providing vitamin A supplements in large-scale experimental studies is impressive—about 25 percent reduction in children in deficient areas (Beaton et al. 1993), and recently shown as nearly half among pregnant women in Nepal (West et al. 1999). Iron deficiency, of which anemia is only one consequence (itself a risk for mortality, especially maternal), also has extensive effects on cognitive development and educability (Gillespie 1998, Viteri 1998). Given how widespread the deficiency is, the cumulative effects on society are enormous, and (like iodine) some of these are irreversible within the lifetime of the individual and can affect the next generation. Effective policies for controlling malnutrition depend on whether the problem is perceived as a priority, and how easy it is to deal with. So far, those problems with the most dramatic presentation have been those most easily addressed, and vice versa, as illustrated in Table 1. Thus iodine deficiency disorders and vitamin A deficiency (VAD) are being tackled effectively, but iron deficiency (usually measured as iron deficiency anemia, IDA) remains highly problematic, and other possible deficiencies, like zinc, vitamin D, and calcium, have only recently begun to be taken seriously. Iodine deficiency disorders and VAD present dramatically and have straightforward technical solutions. Iron and other deficiencies are subtle and the solutions are not clear, partly because they are more difficult, and partly for lack of adequate research. 68 Asian Development Review Table 1: Perceptions and Relative Priorities of Interventions Problem Presentation Intervention Vitamin A deficiency Striking: blindness, increased child Easy in children: infrequent high and maternal mortality risk dose capsules Iodine deficiency Striking: cretinism, dwarfism, goiter Easy: iodized salt Iron deficiency Subtle: anemia, reduced cognitive Difficult: e.g., frequent development supplementation General malnutrition– Subtle: smaller children Difficult: community-based growth failure programs General malnutrition– Striking: emaciated and dying Easy (in principle): emergency starvation in emergencies children and adults food aid and other assistance Source: Mason (1999). Prevalences and numbers affected by general and micronutrient malnutrition among priority groups by region are shown in Table 2 (taken from Mason et al. 1999). For all except IDDs, South Asia has the highest prevalences in the world, and IDDs are of similar prevalences for most developing regions. But significant progress is being made in most of the deficiencies and regions. The progress among interventions to control IDDs and VAD is encouraging, with major acceleration in recent years, whereas control of iron and other less wellknown deficiencies is not yet apparent. This can be related to the inherent nature of the deficiencies. Iodine and vitamin A are needed in minute (microgram) quantities daily, and the effects of one intervention last for several months: thus they are the most open to rapid attack. In contrast, the other minerals of immediate concern are needed in much larger daily amounts (milligrams), should be ingested more frequently, and have complex biological mechanisms. Current evidence is that IDA is persisting at high levels throughout Asia, with no sign of improvement. Trends in other deficiencies are unknown. In addition, the metabolism of iron, calcium, and zinc can be readily inhibited by other dietary constituents, and traditional eating patterns may make it almost impossible for some populations to get enough iron from their diet. Rapidly changing diets may pose other risks. The position for VAD, IDDs, and IDA is reasonably well known, as discussed below. Controlling Micronutrient Deficiencies in Asia 69 Table 2: Regional Prevalences and Numbers Affected by Micronutrient Deficiencies Underweight Anemia Subclinical Iodine Deficiency TGR (preschool) (nonpregnant women Vitamin A Deficiency (all ages) 15-49 years) (preschool) 1995 1975-98 1995 1995 1985-1996 1995 Region Prevalence Est. No. Prevalence Est. No. Prevalence Est. No. Prevalence Est. No. (%) Affected (%) Affected (%) Affected (%) Affected (millions) (millions) (millions) (millions) South Asia 52 87.4 59 149.0 35.6 59.5 17 203 Sub-Saharan Africa 30 30.9 38 41.5 35.3 36.0 18 91 East Asia Pacific 23 39.3 42 140.4 18.2 29.6 21 329 Middle East & North Africa 16 7.4 33 20.3 9.8 4.2 20 42 Latin America and Caribbean 11 6.2 24 27.2 19.6 10.2 11 41 Total 31 171.2 43 378.4 26.5 139.5 18 706 Notes and Sources: Data assembled for “Progress in Controlling Micronutrient Deficiencies” (Mason et al. 2000). Underweight: Figures are from UNICEF (1997) for the % children suffering from moderate or severe underweight, based on 1997 SCN using 1995 as base year. Anemia: Prevalence data is from Progress in Controlling Iron Deficiency, Tulane University and Micronutrient Initiative June 1998. For Latin America and Caribbean: the regional prevalence was determined by weighting the prevalence figures of 27% and 17% with 0.675 and 0.325 for South America and Middle America/ Caribbean respectively. Anemia estimated numbers affected were estimated by calculating the percent pregnant in each region using WHO estimations 1995 and applying these percentages to the 1995 population figures for the regions from UN Population Division 1995 (SOWC 1997). These estimations of non-pregnant women were multiplied by the prevalence of anemia in the region to determine the number of affected women. Adjustments to the age structure from 15-59 used by WHO to 15-49 used in this presentation were made using 1995 population estimations for women (UN 1996). VAD: Prevalence data is from MI/UNICEF/Tulane (1998). VAD Sub-clinical for SSA: weighted the E. & S. Africa and W. & C. Africa figures to collapse into SSA. E & S. Africa was 37.1 % VAD and 18.6 million affected, W & C. Africa was 33.5% VAD and 17.4 million affected, whereas the combined region of SSA is 35.3 % VAD and 36 million affected. IDD: Prevalence data is from Mason et al. (2000). IDD for East Asia/Pacific: weighted the PRC and SE Asia figures to collapse into East Asia /Pacific. The PRC was 20.4% TGR and 236 mill affected, SE Asia was 21% TGR and 93 million affected, thus the combined region is 20.6% TGR and 329 million affected. IDD for Latin America/Caribbean: weighted Middle America and South America figures to collapse into Latin Am./Caribbean. Middle America was 6% TGR and 8 million affected, South America was 13% TGR and 33 million affected, thus the combined region is 10.6% TGR and 41 million affected. 70 Asian Development Review Clinical Vitamin A Deficiency Clinical VAD assessed by eye damage (xerophthalmia) is considered a public health problem at more than 1 percent prevalence, which is low compared to other deficiencies (MI/UNICEF/Tulane 1998). However, by the time clinical signs appear, the deficiency is dangerously advanced. Subclinical deficiency, assessed by levels of vitamin A in the blood (serum retinol) is much more widespread, and considered to be responsible for much of the risk associated with VAD. Prevalences of low serum retinol (<0.7 μmol/l) are in the range of 10-30 percent in the study countries. The estimated prevalences for clinical VAD for 1995 are 0.95 percent for South Asia, and 0.25 percent for East Asia and the Pacific, affecting some two million preschool children in these regions (which include the study countries). The prevalence in South Asia is higher than anywhere else in the world except Sub-Saharan Africa, and compares with an estimated developing country average of 0.6 percent. The estimates for subclinical deficiency are around 10-20 percent, with nearly 50 million children affected. The trend in clinical VAD prevalences can be assessed from certain countries where surveys have been repeated. On average, these indicate that the clinical prevalence has roughly halved over 1985-1995. As examples (from MI/UNICEF/ Tulane 1998, Table 2): India from 1.4 percent in 1976 to 0.7 percent in 1989; Sri Lanka from 1.1 percent in 1976 to 0.3 percent in 1987; Indonesia from 1.0 percent in 1977-1978 to 0.3 percent in 1992; Philippines from 3.2 percent in 1982 to 0.5 percent in 1993. These changes between successive surveys at country level are similar to the global estimates. Thus it does appear that there is a strong underlying trend of improvement in clinical VAD. The estimates from large-scale surveys (n>1000) since 1980 for Asia, and Africa for comparison, are shown in Figure 1a. Asian results are in Figure 1b. While the scatter is large, the improving trend is apparent here (and is significant for the combined data). Attention is turning to subclinical VAD, catalyzed by the finding that child mortality is greatly reduced by prevention of VAD, and that this must operate through preventing subclinical forms (Beaton et al. 1993). Recently, supplementation to prevent subclinical VAD has also been shown to dramatically reduce maternal mortality (West et al. 1999). It is likely that subclinical VAD is declining in general, but nonetheless it will be at least 20 years before the average subclinical prevalence is down to 5 percent, and meanwhile many preventable deaths will have occurred, and many highly vulnerable groups will still be affected. The country-specific VAD prevalence and trend estimates, largely from the country reports, are given in Mason, Hunt et al. (2001). All this argues for building on the presently favorable underlying trend, to maintain supplementation programs, and to develop effective fortification in the interim. Controlling Micronutrient Deficiencies in Asia 71 Figure 1a: Clinical Vitamin A Deficiency (xerophthalmia): Prevalence Trends in Preschool Children from Surveys since 1980