0.2 Trends in nutrition and infection Flashcards
Overview
Malnutrition is extremely prevalent occurring in both affluent and poor societies. Global WHO data shows that 39% of adults are overweight (13% obese) but that a further 8.9% are clinically underweight. This data doesn’t include those with ‘hidden malnutrition’ – the micronutrient deficiencies of public health significance (vitamin A, zinc, iron and iodine) nor the food insecure. In resource poor parts of the world, populations may lack access to sufficient food, or sufficient dietary diversity and this leads to undernutrition, micronutrient deficiencies and a subsequent immune-incompetence. The ‘double burden of malnutrition’ is when undernutrition and overnutrition are seen side by side within a country. Unfortunately, the risks from overweight and obesity are greater in people who were undernourished at birth and/or their early years.
Overview
The economic transition of countries, from poor to rich, is associated with increasing levels of over-nutrition and a subsequent rise in non-communicable diseases (NCDs) such as cancer, diabetes and cardiovascular diseases but also with a fall in many infectious diseases. Globalisation and urbanisation together predispose people to obesity when the availability of cheap, convenience foods increases. The trend during economic transition is for the risks of undernutrition to give way to the risks of obesity and NCD’s.In affluent societies there is a striking prevalence of overweight and obesity which can be associated with overconsumption, lack of physical activity and changes in dietary patterns which have been complicated by the high availability of poor-quality processed foods. Despite the high prevalence of obesity there is relatively little known about the effects of being overweight on infectious diseases.
Overview
The fight against undernutrition has been going well this century, due at least in part, to an increased political will to tackle the issue and a global consensus on how to address the issues; significant progress has been made in many areas, UNICEF/WHO/World Bank Group (2021). In 2008, the Lancet published work by Bhuttaet al.which outlined a series of low cost, effective direct nutrition actions to reduce acute undernutrition. Indirect nutrition actions were also outlined in the series. Nutrition and infection are inexorably linked and need to be tackled together in order to promote health and well-being. This session will present information and context to examine the evidence for their interrelationship.
Learning objectives
After working through this session, you will be better able to: discuss the importance of synergistic interaction between disease and nutrition; discuss recent developments in the nutrition sector; and access and explore key learning resources particularly with reference to the evidence concerning undernutrition and infection.
Key terms Malnutrition
Relates to both over- and undernutrition. It includes stunting, under-weight, wasting, obesity and micronutrient deficiencies. It can be chronic or acute.
Key terms Undernutrition
Relates principally to an inadequate energy intake but can include micronutrient deficiencies. It can be chronic or acute.
Introduction
Knowledge surrounding many aspects of our nutritional status increased during the 20thcentury, including its effects on health, economic productivity and mortality. However, a series of key events in the early 21stcentury further increased interest in tackling malnutrition. The Copenhagen Consensus, a thinktank of Economists, consistently demonstrated the cost-effectiveness of interventions to improve nutrition and global well-being. The 2008 and 2013Lancetseries on Maternal and Child Undernutrition reviewed and consolidated the evidence to date outlining the effects of undernutrition on infectious diseases, associated morbidity and mortality. In 2014, the Global Nutrition Report was launched as an accountability mechanism to track progress against global nutrition targets.
Introduction
The causes of malnutrition are multi-faceted crossing a range of disciplines which arguably makes studying it more challenging. Health and public health factors, diet and food production factors, socio-economic changes, education, gender equality and development are all determinants of nutritional status. Thus, the larger context must be considered. Despite these complicated inter-relationships, it is now widely acknowledged that coordinated action by stakeholders is feasible and leads to highly significant gains in terms of reduced morbidity, mortality and increased economic productivity.
The causes of malnutrition
The causes of malnutrition are multi-factorial and not due solely to a poor or indeed excess food availability and intake. Factors as varied as societal norms, mother’s education and/or cultural beliefs, access to clean water all influence food intake and nutritional status.
The causes of malnutrition
UNICEF devised the accepted causative conceptual framework for malnutrition, see Figure 1 in the 1970’s. The two immediate factors that lead to malnutrition are inadequate dietary intake and disease. An inadequate food intake itself results from many factors such as the high cost of food, poor access to food or complex and deeply embedded cultural norms such as poor infant feeding practices.
The causes of malnutrition
The UNICEF conceptual framework further divides down to underlying causes: 1.Inadequate access to food. Is food in the market? In the house? Who has first choice of the food available? This is strongly cultural. 2. Inadequate care and support of women and children. Childcare takes time. Does the primary carer have the education, time and agency to feed infants appropriately? Is quality ante-natal care in place? Is maternity leave in place? 3. Insufficient public health environment.Is an immunisation programme in place? Is the water quality good? Is sanitation and access to basic health care good? This framework has proved to be a useful tool for structuring thought and discussion around the determinants of undernutrition and in children in particular.
Mortality, infectious disease and undernutrition
The effects of undernutrition on morbidity and mortality are additive to those from the infectious disease. The profound nature of this information has led to much research and a deepening understanding of the link between undernutrition and disease. Multiple studies have highlighted that a malnourished child is much more likely to contract an infection, more likely to suffer morbidities more severely and for a longer period of time. Three studies that demonstrate these points clearly are Bryceet al.(2005); Caulfieldet al.(2004a); Pelletier (1995).
Mortality, infectious disease and undernutrition
The relative risk of dying from underweight is elevated for any individual cause of death as well as for all-cause mortality (Caulfield et al., 2004a). Diarrhoea has the most negative synergistic effect with severe underweight leading to a 12-fold increase in mortality whilst malaria leads to a 9.5-fold increase in mortality rate. This means, that a severely malnourished child who contracts malaria is 9.5 times more likely to die than if they were not malnourished. Overall, the severely underweight have an 8.7-fold increased all-cause mortality.
Mortality, infectious disease and undernutrition
Epidemiologists, have also established childhood underweight as the leading cause of the global burden of disease. In 2011, it was estimated that 45% of all deaths under 5 years, had undernutrition as the underlying cause i.e., mortality would not have occurred had the child been adequately nourished (Blacket al., 2013).The excess mortality in the undernourished is not restricted to the severely, visibly ‘starving’ children. Pelletier’s work from 1995 demonstrated for the first time that the majority of deaths (~ 75%) occurred in children with only mild to moderate undernutrition. These children are almost impossible to detect visually and would need to be identified by anthropometric or other means. There are significant regional differences in mortality across the globe and this is clearly represented in Figure 2 (Bryceet al., 2005).
Activity 1 Figure 2 shows the numbers and causes of death of children under five around the world. Consider the following questions. What is the significance of the pie chart and what are the reasons for the different sizes?
The larger the pie chart the higher the number of child deaths in that region. Different factors that will affect this number include the size of the under-five population, the geographical spread of different diseases, the availability/access/effectiveness of the local healthcare provision, the nutritional status and resilience of the under-five population, the standard of care practices for the child population.
