THE LASTING DAMAGE OF EARLY MALNUTRITION
Professor Nevin S. Scrimshaw
The single most devastating news for developing countries is that widespread nutritional deficiencies are inflicting lasting damage on the physical and mental capabilities of their populations. Worse for the mission of the World Food Programme is that these deficiencies are more severe wherever food shortages occur as a result of the many crises in today's world. To the periodic food shortages associated with drought, floods, and economic collapse must be added the tragic increases in malnutrition among refugees from civil disturbances and war. Wherever and whenever governments and relief and development agencies neglect attention to the nutrition of pregnant and nursing mothers and to infants and young children, they are compromising the human resources on which a country's future depends.
Apart from mortality, the most serious consequence of nutritional deficiencies during pregnancy and infancy is interference with brain development at critical times. There is now strong evidence, that inadequate iodine intake during pregnancy, iron deficiency anaemia in infancy, and early protein-energy malnutrition can have permanent effects on intellectual performance throughout life. In addition, malnutrition in infancy and early childhood not only contributes to increased morbidity and mortality in childhood, but also the resulting stunting means lower physical work capacity of adults. Even less appreciated is the growing evidence that foetal and infant malnutrition results in the earlier onset of chronic degenerative diseases in later life.
It follows that international, bilateral, and private voluntary agencies and governments need to ensure that the nutrition of mothers and young children is not neglected. It would be inappropriate in this presentation to cite individual studies supporting the statements that I am making, but my conclusions are based on the consensus of internationally organized workshops and reviews that are listed in an accompanying bibliography.
The two most common and widespread deficiencies, those of the essential trace minerals iodine and iron, are hidden hungers because they are seldom recognized, even by health workers. This is because their devastating consequences for mothers and young children are not associated with obvious clinical signs.
Iron deficiency is the most widespread nutrition problem in the world today. Anaemia due to insufficient iron is found in 40% to 60% of the women and children of many developing countries (i.e. 59% of pregnant women; 49% of non-pregnant women; 51% of children 0-4 years; and 46% of children 5-12 years [WHO]). When anaemia rates are this high, nearly all of the rest of a population has some degree of subclinical iron deficiency. The effects of iron deficiency in infancy include:
Long before its cause was known, the pallor of anaemia was associated with weakness and tiredness. It is now recognized that iron deficiency anaemia in infancy affects brain development at a critical time, and that its effects on cognition at this time are not corrected by subsequent improvement in iron status. Iron deficiency also depresses immune status in all age groups and results in increased morbidity from infections.
The impact of iron deficiency anaemia in delaying psychomotor development and impairing cognitive performance has been definitively demonstrated in infants and preschool children in Chile, Colombia, Costa Rica, Egypt, Guatemala, Indonesia, and the United States. Figure 1 shows the relationship between haemoglobin status and psychomotor test scores for infants in Costa Rica. These effects were not reversed by iron supplementation and were evident at school age, even when anaemia was no longer present.
PSYCHOMOTOR DEVELOPMENT SCORES AT DIFFERENT LEVELS OF IRON DEFICIENT COSTA RICAN INFANTS
There are also many studies confirming the effects of iron deficiency anaemia on the cognitive performance of school children and adolescents, including ones in Egypt, India, Indonesia, Thailand, and several in the United States. Whether, iron supplementation corrects the cognitive impairment in these age groups seems to depend on the age at which the iron deficiency first occurred. In Indonesia, the effect in school children was partially reversible. In 2,000 Bangkok school children, those with iron deficiency anaemia showed poorer performance on tests of Thai language and mathematics than did those with normal haemoglobin levels. These effects were not reversed by iron supplementation that successfully corrected their anaemia.
Thus, while iron deficiency can impair cognitive performance at all stages of life, the effects of iron deficiency anaemia in infancy and early childhood are not likely to be reversed by subsequent improvement in iron status. Ten percent of infants in many industrialized countries and 30% to 80% of those in developing countries are anaemic at one year of age. The psychomotor development of these children will be reduced by the equivalent of 5 to 10 I.Q. points. When they reach school age, they will have poorer performance on tests of coordination, language, mathematics and motor skills.
Iron deficiency anaemia during pregnancy also increases maternal mortality, as well as prenatal, and perinatal infant loss. Moreover, if the mother is iron deficient, her child is born with poor iron reserves and is at greater risk of morbidity and mortality during infancy. Iron deficiency in children can also inhibit growth, impair immunity, and increase childhood morbidity from infectious disease.
Iodine deficiency occurs widely where water and soils are deficient in this mineral, and therefore the plants and animals do not supply enough of it in the diet to allow adequate production of thyroid hormone. Despite good progress of international efforts to achieve the universal iodination of salt for populations at risk, it is estimated that over a billion people are still at risk of damage from iodine deficiencies. The defects of the offspring of iodine deficient mothers (according to ACC/SCN) are as follows:
The immediate effect of iodine deficiency is an enlargement of the thyroid gland of the neck to form what is called a goitre. It has long been known that in populations with a high prevalence of goitre, some cases of cretinism, feeble-minded dwarfs, are likely to be found. There is also an increased prevalence of deafmutism.
It has been increasingly understood in the last two decades that these readily recognizable outcomes of iodine deficiency in pregnancy are like the tip of a vast undersea mountain of individuals for whom iodine deficiency in-utero in the early months of pregnancy can cause impairment of brain development. The result is that the intellectual capacity of the entire population in goitrous villages or regions is affected to some degree.
Figure 2 shows the difference in the distribution of intelligence quotients in selected villages in China with a high prevalence of iodine deficiency and in others with adequate iodine intake. In similar studies in Papua New Guinea, Zaire, Ecuador, and Peru the shift in the distribution of I.Q. with correction of iodine deficiency in a population can amount to as much as 10 to 15 points.
STUDENTS IN SOCIO-ECONOMICALLY SIMILAR CHINESE COMMUNITIES
(Ma et al. 1994)
Figure 3 shows the improvement in the distribution of I.Q. in villages in Zaire after administration of iodized oil to women of child-bearing age. Similar results have been reported from other countries and can be expected wherever endemic goitre is eliminated as a public health problem.
EFFECT OF IODIZED OIL, ZAIRE
(Vanderpas and Thilly 1994)
WHO data give the proportion of children who suffer some degree of protein-energy malnutrition, as judged by the degree of retardation in weight for age, as about 10% in Latin America, 20 to 30% in Southeast Asia, 20 to 40% in Africa, and a staggering 40 to 60% in South Asia. Most of these children are stunted, but some are wasted as well. It has been known for many years that stunted and/or wasted children have poorer performance on tests of learning and behaviour. Some of the better known intervention studies showing improvement with nutritional supplementation of preschool children are from Chile, Colombia, Guatemala, India, Jamaica, Mexico, Peru, Taiwan, Uganda, and Yugoslavia, but none of these provided proof that the benefits persisted into adulthood.
Two of the studies demonstrating a prompt benefit from improving the nutrition of poorly nourished infants and young children were followed up. These were two well designed classical intervention studies in Guatemala and Mexico.
In the Guatemala study a protein-rich supplement given between 6 and 36 months of age in two villages resulted in increased growth and improved performance on appropriate behavioural tests as compared with suitable control children in two other villages who received a low-calorie, protein-free beverage and the same social stimulation. When these studies ended, the interventions ceased. Approximately 14 years later the original investigators returned and were able to examine most of the participants in the original study, now adolescents and young adults.
They found that growth differences had persisted in the nutritionally supplemented group and the males had better physical capacity as judged by treadmill performance. More striking and important, they had completed more years of schooling, and had performed significantly better per year of schooling on the Central America achievement test that combined literacy, reading, vocabulary, numerical and general knowledge, and Raven's Progressive Matrices. Overall, the cognitive gains that were small at two years of age were now medium to large.
In Mexico, supplemented and unsupplemented children were randomly selected in the same village so that other potential influences were similar for both groups. The supplemented children received a nutritious milk and fruit beverage as soon as their growth began to falter and this was continued until they were ten years of age. Figure 4 illustrates the subsequent consistently better cognitive performance of those individuals supplemented as preschool children and observed until they were young adults.
EARLY CHILDHOOD SUPPLEMENTAL FEEDING AND LATER DEVELOPMENT, MEXICO
(Chavez et al., 1995)
Differences in social stimulation between privileged and underprivileged groups and individuals do contribute importantly to the differences observed in their educational performance. However, the Guatemalan, Mexican, and other studies demonstrate that the effects of early malnutrition are superimposed on any differences due to social factors and must be corrected before children reach the age when it is too late to do so.
Adult consequences of foetal and infant malnutrition
One of the most surprising recent developments is the accumulating evidence that poor nutrition during foetal development and infancy influences the occurrence of chronic diseases in adulthood. Foetal growth restriction due to maternal malnutrition and other adverse environmental factors leads to a small-for-gestation baby. Today this is common throughout the developing world; but in the past, it has been characteristic of lower socioeconomic groups in today's industrialized countries.
David Barker and colleagues have identified individuals in England, born earlier in this century, who suffered foetal growth retardation and/or stunting at 12 months of age. Weight at birth and weight at one year of age proved predictive of earlier adult onset of hypertension, cardiovascular disease, non-insulin dependent diabetes, and chronic thyroid disease.
For example, men born in Preston, England between 1935 and 1943, with either low head circumference or low ponderal index (birth weight divided by birth length), had higher mortality rates from cardiovascular disease. This finding has also been reported from other studies in Sheffield, England; Caerphilly, Wales; and Uppsala, Sweden and by analysis of data from the United States' nurses health study. Figure 5 shows the progressive decrease in adult deaths from cardiovascular disease, with increased weight at one year of age, for men born between 1911 and 1930 in Hertfordshire, England.
STANDARDIZED MORTALITY RATIOS FOR ISCHAEMIC HEART DISEASE ACCORDING TO WEIGHT AT 1 YEAR OLD IN 6500 MEN BORN DURING 1911-1930
A follow-up study of the populations of Preston and Hertfordshire, a national sample in Britain, and a study of men in Sweden showed a similar relationship between high blood pressure and low birth weight. A systematic search of the literature found 32 papers that overall showed a tendency for blood pressure to increase as birth weight goes down. The only study of this type in a developing country, a recent report from India, also describes such a relationship.
Birth weight and/or ponderal index has been found to be inversely related to impaired glucose tolerance and non-insulin dependent diabetes in adults in the United Kingdom, American Pima Indians, United States male health professionals, and Swedish men. A similar relationship between weight for age at one year and glucose tolerance for the Hertfordshire population, is shown in figure 6. These observations help to explain why increased affluence leads to such high diabetes rates in formerly undernourished populations.
PROPORTIONS OF 370 MEN AGED 64 WITH IMPAIRED GLUCOSE TOLERANCE, HERTFORDSHIRE
(Hales et al. 1991)
It is clearly important to prevent low birth weight for a normal gestation period, both because of its adverse implications for morbidity and mortality in early childhood and its long term consequences. The rarity of low birth weight for age in well nourished populations confirms that it is due almost entirely to nutritional and related environmental factors. Small infants are also born in well nourished populations, but these are usually "prematures" with normal weight for the period of gestation and generally have normal postpartum growth and development if they are large enough to survive.
Conclusions and recommendations
From the foregoing the following conclusions should be self-evident. Restriction of nutrients in utero and in the rapidly growing infant can permanently change or programme the physiology and structure of the body. As long as each generation of a population is handicapped by the consequences of malnutrition during the foetal period or during infancy and the preschool years, educational and development goals will be difficult to achieve for that population.
Improving the nutritional and health status of women is a key to improving that of young children, particularly in Asia. This includes taking into account the importance of adequate food during pregnancy and lactation and particularly the need for foods for appropriate complementary feeding of breastfed infants after four to six months of age. Improving the educational and economic conditions of women is part of the process.
Prevention of protein-energy deficiency in toddlers requires the availability of a suitable weaning food. The components are almost always available locally for vegetable protein based mixtures that are of adequate nutritional value, but in emergency situations milk or a vegetable blend that is suitable for complementary feeding of young children should be made available.
Iron deficiency disorders can be reduced at minimal cost by fortification of cereal flours and cereal products, but unfortunately is not feasible for the cereal grains that are the bulk of relief foods. Recent studies have demonstrated that weekly iron supplementation is effective for the correction and prevention of iron deficiency anaemia. For preventing the multiple vitamin and mineral deficiencies common in refugee populations, multivitamin tablets are inexpensive and effective.
Universal iodination of salt is the most practical solution to the problem of iodine deficiency, and should be supported by all of the relevant international agencies as a component of development assistance. However, for refugees in endemic goitre areas, a suitable iodine compound can be added as part of the fortification of cereal flour or to iron tablets until salt iodination becomes a reality.
In addition to these three nutritional deficiencies with lasting impact, vitamin A deficiency adds to preschool mortality. The historically important vitamin deficiencies that cause the scurvy, beriberi, and pellagra that are being seen in some refugee populations must also be prevented by taking them into account in planning and implementing food aid. Fortification of appropriate staple foods with the vitamins and minerals likely to be deficient is the most practical and cost-effective way to prevent damaging vitamin and mineral deficiencies in refugee populations. However, their prevention as part of development assistance should involve a combination of dietary improvement, food fortification, and nutritional supplementation.
As important as is nutritionally oriented food assistance from WFP, the contributions of other UN agencies are also needed to end the inheritance of hunger. Complementary to food based programmes are the promotion of improved environmental sanitation and personal hygiene to reduce the burden of diarrhoeal disease and immunizations to prevent the common communicable diseases of childhood. So also is the availability of acceptable family planning methods. Agricultural and economic development programmes are equally essential.
The evidence is now clear that if it is to be of maximum benefit to the future of the populations assisted, all food and development assistance to needy populations must take into account the needs of young children. It is no longer morally acceptable to be satisfied with ensuring that the food needs of older children and adults are met. There are lasting consequences when iodine deficiency during pregnancy and iron and protein-energy malnutrition in young children are allowed to persist.
In the words of Gabriel Mistral:
"Many things we need can wait.
The child cannot.
Right now is the time his bones are being formed,
his blood is being made and
his senses are being developed.
To him we cannot answer - 'Tomorrow'
His name is today"
Prevalence of specific kinds of malnutrition
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