Public Health Nutrition

CHAPTER 13 Public Health Nutrition






13.2 INTRODUCTION TO FOOD AND NUTRITION POLICIES AND INTERVENTIONS


Nutrition policies and interventions are designed to reduce malnutrition in populations. In this chapter the term ‘malnutrition’ encompasses both undernutrition (due to some combination of food, care and health deprivations) and overnutrition (due to a combination of the excess consumption of some diet components and too little physical exercise). Governments have an important role in the elimination of malnutrition because:



Democratically elected governments have human rights obligations, including the right to adequate nutrition, and are directly accountable to the populations they serve.


The extent of various types of malnutrition differs between developing and developed countries: general undernutrition and specific vitamin and mineral deficiencies are more prevalent in developing countries, whereas chronic diseases related to poor nutrition, such as obesity, CHD, diabetes, and osteoporosis (sometimes referred to as ‘overnutrition’ or ‘diseases of affluence’) are more prevalent in developed countries. For simplicity the term ‘overnutrition’ is used here although it does not express the compositional imbalance of many diets in affluent countries. However, pockets of undernutrition exist in developed countries and nutrition-related chronic diseases are expanding rapidly in the developing world. Undernutrition and nutrition-related chronic diseases coexist to the greatest extent in countries undergoing rapid socioeconomic and demographic transitions such as the countries of the former Soviet Union. The challenge of balancing interventions to address under- and overnutrition is particularly great for these countries.


Good nutrition is related to access to and appropriate utilization of available food. Food supply is therefore part of the equation. The second part of the chapter therefore deals with various factors that affect world food supply and the ability of the world to provide enough food for an increasing population.



13.3 EXTENT AND CAUSES OF MALNUTRITION


Descriptions of malnutrition are usefully classified by stage in the lifecycle. Dramatic growth failure most typically occurs between the ages of 12–18 months with a low probability of catch-up growth. The impairments in cognitive function are also largely irreversible. Hence early infant malnutrition has consequences throughout the lifecycle. Malnourished babies become malnourished adolescents and adults who are less able to learn in school and less productive in the labour market. Malnourished female babies are more likely to be malnourished girls and women who give birth to malnourished babies. Moreover the fetal origins hypothesis (see chapter 6) proposes that maternal dietary imbalances at critical periods of development in the womb can trigger adaptations that affect fetal structure and metabolism in ways that predispose the individual to chronic diseases later in life. This section reviews the extent and causes of malnutrition at different stages in the lifecycle.



Assessment of extent and worldwide distribution of malnutrition


A rough approximation of the extent, pattern and trends of the malnutrition problem can be estimated using existing data. Until recently the international organizations concentrated on documenting only nutritional status in developing countries. However, since about 2000 they have started to include the epidemiology of obesity and diet-related degenerative diseases.


Stunting (low height for age) and underweight (low weight for age) of infants in the developing world is widespread. A third of all children under the age of 5 in developing countries are stunted and underweight. In South Asia almost half are underweight, although nutritional status in all regions of the world except sub-Saharan Africa has been improving over recent decades (Table 13.1)


Table 13.1 Percent of pre-schoolers (under-5s) that have low weight for age


































Region Percent under-fives underweight
  1990 2000
Developing countries 32 28
East Asia/Pacific 24 16
Latin America/Caribbean 11 8
Middle East/North Africa 13 17
South Asia 55 48
Sub-Saharan Africa 32 31

Source: UNICEF 2003 (http://www.childinfo.org/eddb/malnutrition/index.htm; accessed 29 July 2003)


The proportion of adults who fall below the cut-off for underweight (BMI < 17) and above the cut-off point for obesity (BMI ≥ 30) is shown in Table 13.2. The poorest countries are therefore still grappling with underweight and the developed countries with overnutrition issues such as obesity. Despite the widespread efforts to reduce the extent of obesity and its associated diseases, their prevalence continues to increase.


Table 13.2 Percent below and above BMI cut-offs: adults in 2000























  BMI < 17 (underweight) BMI ≥ 30 (obese)
Least developed (n = 45) 8.9 1.8
Developing (78) 6.9 4.8
Transition (27) 2.4 17.1
Developed market (24) 1.6 20.4

Source: WHO 2002 (http://www.who.int/nut/db_bmi.htm; accessed 9 September 2002)


The major micronutrient deficiencies worldwide are iron, iodine, and vitamin A. Approximately 2 billion individuals worldwide are iron deficient, 750 million are iodine deficient and 160 million are vitamin A deficient. In developed countries certain other potential micronutrient deficiencies have become more of a concern in recent years. These include folate deficiency in women in relation to spina bifida in a small percentage of newborns, but also in men and women in relation to elevated plasma levels of homocysteine levels related to coronary heart disease.


Anaemia prevalence is used as a proxy for iron deficiency. In industrialized countries this is likely to be a close approximation, but in the developing world anaemia can occur due to factors other than iron deficiency such as malaria, other parasitic infections, current infectious diseases and other pathologies. Anaemia is a serious problem throughout the lifecycle, both in industrialized and developing countries where the prevalence is over 10% and 14% respectively. It is a particular problem for pregnant women who have high haematinic needs, with a prevalence of almost 20% in industrialized countries and almost 60% in developing countries (see chapters 5 & 8).


One of the most visible manifestations of iodine deficiency is goitre (see chapter 5) and this is used as one indicator of deficiency. The overall world prevalence of goitre is 13%, highest in the African region (20%), followed by Europe (15%), SE Asia (12%), Western Pacific (8%) and the Americas (5%)


Severe vitamin A deficiency (VAD) manifests itself clinically as night blindness and corneal xerosis (see chapter 5). Sub-clinical vitamin A deficiency in pre-school children is defined as serum retinol level <0.7 μmol/L. While clinical signs of vitamin A deficiency are relatively rare (estimated 3 million pre-school children), subclinical deficiency, which increases the likelihood of morbidity and mortality in pre-schoolers, is estimated to be widespread (75–250 million) in developing countries only, and most likely found in South Asia and sub-Saharan Africa.


In addition to anthropometric data and patchy micronutrient status data, food balance sheet data are available for most developing countries for most years. These data are compiled by the UN’s Food and Agriculture Organization (FAO) from food production, food trade and food aid flows. The foods are converted into calories and divided by population size to give the dietary energy supply (DES) in calories per capita. The DES numbers are converted to estimates of the percentages of individuals without adequate access to food: 17% in developing countries, with the highest in sub-Saharan Africa (33%), and 7% in countries in transition.


Some of the factors behind the tragic decline in nutrition status in sub-Saharan Africa include: closed markets in the developed world (especially the EU) for their exports; HIV/AIDS generating a health and development crisis and undermining the ability to respond to the crisis; wars and refugee movements; military expenditure; drought; crop and livestock disease; many ecosystems making technology diffusion and adaptation difficult; under-investment in agricultural research; no economy serving as regional driver (Nigeria and South Africa’s under-whelming economic performance); low levels of human capital in terms of literacy; declining terms of trade for natural resources on world markets; low population densities leading to thin infrastructure and market institutions.



Analysis of causes


Figure 13.1 summarizes the causes of undernutrition in children, but much of this scheme is also relevant to adults. The causes lie at several levels (immediate, underlying and basic) and in many sectors (agriculture, health, water, education, and employment, etc). It is important to understand the causes of malnutrition to guide the interventions needed to improve nutrition status. The following examples focus first on undernutrition, followed by similar analyses that can be made for the chronic nutrition related diseases (overnutrition).




Immediate causes


The most immediate causes of malnutrition in young children (and also adults) are poor diet and infection (see chapters 6 & 8). If the child is not able to ingest enough food, both in terms of quantity and quality that can be used for growth and development, then malnutrition occurs. Infection and an inadequate diet reinforce each other as infection reduces the intake of nutrients by diminishing appetite, inhibiting nutrient absorption, and increasing nutrient requirements for combating infection while poor diet reduces the effectiveness of the immune function.


Equivalent immediate causes of diseases of affluence are excess intake of food, eg through bottle feeding, snacking, high fat foods, and lack of exercise.



Underlying causes


Underlying causes of undernutrition include household food insecurity, poor care for mothers and children and the inadequate provision of health services and an unhealthy environment. Food security ‘exists when all people, at all times, have physical and economic access to sufficient, safe, and nutritious food to meet their dietary needs and food preferences for an active and healthy life’. Household food insecurity has many interrelated causes: poor crop yields, low incomes, high food prices, low rates of exchange between food and non-food, and a lack of access to assets, including land, water, extension and credit.


Poor health services, unclean drinking water, and non-existent hygiene disposal systems all increase the likelihood of infection, particularly diarrhoea. Inadequate care for mothers and children increases the risk of infection and inadequate diet. Care includes time for resting and appropriate food during pregnancy, breast feeding and feeding of young children, psychosocial stimulation of infants, food preparation and storage practices, hygiene practices and care for children during illness, including diagnosis and health seeking behaviour.


Underlying causes for the diseases of affluence are mainly the converse, including overall food security, availability of plentiful and varied food products (although not always the most healthy), food advertising, a sedentary lifestyle at work and leisure due to labour saving devices, transport, computers, work pressures, and increased perception of risk for children in playing outside and walking or cycling to school.



Basic causes


The basic or root causes of malnutrition are essentially political and economic. There are very few instances of high levels of undernutrition (as opposed to overnutrition) above a certain GDP per capita. A 10% increase in income produces a 5% reduction in the rate of undernutrition but income growth is by no means sufficient, and there is a wide range of levels of undernutrition at a given income level. Other factors beyond income growth are obviously essential for good nutrition, such as good levels of education, social equity, and enlightened government behaviour. Good governance – by which we mean institutions that give voice to all parts of society; respect for the civil, political, economic, social and cultural rights of its citizens; and appropriate levels of investment in public goods such as safety, research, roads, health and education – is more likely to produce these conditions. Good education levels mean that individuals know how to access, assess, and use information that is helpful to the attainment of good nutrition status (such as the right types of foods to consume, what to do in the case of diarrhoea, and the optimal duration of exclusive breastfeeding). The status of women relative to men is a dimension of society and values that is crucial to the nutrition status of women and of infants.


The basic or root causes of the diseases of overnutrition are also essentially political and economic, affecting incomes, employment, work pressures, food prices, etc.


Jun 13, 2016 | Posted by in ENDOCRINOLOGY | Comments Off on Public Health Nutrition

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