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Health Studies
R Song

Lecture 7: Nutrition, Growth, and Long-Term Consequence I February 27, 2012 “Ecological Reality of Poverty”  Poverty is harmful to the physical, socio-emotional, and cognitive well-being of children, youths, and their families Life History Approach to Human Adaptation  ‘The study of the evolutionarily derived strategies used by organisms to allocate “energy toward growth, maintenance, reproduction, raising offspring to independence, and avoiding death”’ (Bogin and Smith 2000; Bogin et al. 2007) o Stages of growth from conception to maturity o Timing of reproductive events o Inevitable trade-offs that occur in growth and reproduction Requirements for Life  Macronutrients : large amounts required; critical for providing energy (calories/joules) o Carbohydrates (mono-/di-/polysaccharides) o Fats (simple, compound, derived) o Protein (essential/non-essential amino acids) Micronutrients : smaller amounts required; critical for regulating biological functions  Micronutrients: smaller amounts required; critical for regulating biological functions o Vitamins (water-soluble, fat-soluble) o Minerals (inorganic elements) o Water Malnutrition  Any type of poor nutrition (too much/little)  Economic and socio-political causes  Problem of distribution, but also production, since there is variability in the ability to produce food at local level (and differences in population size)  Human ecological view: malnutrition is a measure of ecological failure (population has not successfully adapted to its environment) Consequences of Malnutrition 1. Weight (fat, muscle) loss 2. Slowing / cessation of growth 3. Immune system impairment (& increase in morbidity) 4. Cognitive / psychological / behavioural impairment (apathy and inactivity) 5. Reduced fecundity (total potential for kids that a woman can have) and fertility (women) 6. Increased labour time / risks to mother & baby 7. Increased infant mortality (due to labour, lactation) 8. Reduced work capacity / efficiency / activity (in adults) 9. Adult diseases (heart, diabetes, metabolic, etc.) 10. Increased / early mortality (malnourished young children and adults) Factors to Consider with Malnutrition  Growth faltering is not only a product of energy deficiency; also: protein, zinc, calcium, sulfur, iron  Repeated infections also reduce appetite and absorption of nutrients in the gut, resulting in shortage of dietary energy and other nutrients secondary to infection (unrelated to intake amount)  Some infections, especially those accompanied by fever, also increase requirements for dietary energy Malnutrition- Infection Interactions  Start off in one of two ways: 1. Poor nutritional status leads to impaired immunocompetence (how well your immune system deals with infections) and reduced resistance to infection 2. Exposure to infectious disease leads to a combination of: anorexia / appetite loss, malabsorption (nutrients not absorbed), elevated BMR due to fever, and protein catabolism (required in production of acute phase proteins needed in immune response) – resulting in malnutrition Simplified Malnutrition-Infection Model  Shows a simplified version of how malnutrition interacts with infection) Infection-Nutrition Complex  Usually Synergistic (two factors work together to exacerbate the situation)  Strong association between moderate to severe malnutrition (e.g., kwashiorkor) and history of prior episodes of infection  Diarrhea - most important factor precipitating malnutrition, then disease, in children  Any infection worsens nutritional status (and affects growth and development, if not causing death) – via impairment of digestion, nutrient absorption, GI/urine loss of nutrients, competition for host’s nutrients  Mucosal damage and depressed immunity are the major ways infection defence is compromised  Cyclical, exacerbating, often a downward spiral  Nutrition-infection processes associated with growth faltering of children Quiz # 1: Malnutrition and infection work synergistically together to:  Worsen the original precipitating condition Immuno-competence and Growth Faltering  Exposure to infection results in immune response  PEM affects immunocompetence: B lymphocyte development and response to antigenic challenge  Repeated exposure and continuous activation of acute phase response of immune system is energy draining  With insufficient protein (due to diet, infection): amino acids drawn from the body, thus exacerbating nutritional status……affects bone development and growth Three Types of Malnutrition  Energy (calories)/ PEM (Protein Energy Malnutrition); most severe  Protein (e.g. Kwashiorkor)  Micronutrient (“marginal”); least severe Protein and Calorie Malnutrition  Deficiency in energy content of food, measured in kcal (kilocalories), and/or deficiency in protein  Ranges from total starvation to moderate forms of under-nutrition, to diets that are sufficient in caloric content but lacking in sufficient protein  Protein malnutrition is leading form of malnutrition (most common), esp. in poor and tropical regions where common foods are high in carbohydrates but low in protein (e.g., rice, corn) o It’s invisible, hard to determine whether the person is malnourished because their type of diet may influence the amount of protein it contains  Prevalent in those with parasitic infections - lose protein to parasites or through leakage of blood due to parasite’s activities; and in weaning infants (due to poor weanling diet and increased protein demands with growth) Protein-Calorie Deficiency  Protein deficiency plus “negative energy balance”: when a person’s dietary energy consumption is less than their energy expenditure (basal and active metabolism)  PEM Effects of Protein-Calorie Malnutrition 1. Weight loss (from fat, body protein from skeletal muscles) 2. Consequences of protein deficiency 3. Reduced work capacity 4. Increased labour time, increasing risks to mother/baby 5. Lactaction difficulties and increased infant mortality 6. Psychological/behavioural: apathy and inactivity 7. MARASMUS: muscle depletion of kwashiorkor with a loss of most body fat; slowing/cessation of growth; characteristic “wizened” (old) appearance of head; vomiting, diarrhea (dehydration); increased susceptibility to disease (most will die of infectious/diarrheal diseases); lethargy, irritability o Extreme weight loss, slow growth, little old skinny people o The body has used up all the nutrients within the body, it starts consuming itself Chronic Protein Malnutrition in Children  Often begins in utero: protein deficiency during pregnancy leads to reduced birth weight and greater risk of infant mortality o Condition and diet of their mothers  Infant malnutrition entails slowing or complete cessation of growth (skeletal and reproductive development), resulting in retarded skeletal maturity and delayed menarche in girls  “Catch-up” growth: compensatory faster rate of growth after period of malnutrition (if it ends before growth period is over); children can often attain normal stature-for-age after catch-up period (girls better able to recover from protein deficiency than boys) o Extension of growth period  Severe protein deficiency results in KWASHIORKOR: muscle atrophy, growth failure, skin rash, edema, de-pigmentation of skin/hair, distended stomach indicating loss of abdominal muscle tone and edema (excess fluid) o Impairment of growth o Edema: water retention, especially in abdomen, collection of fluid Kwashiorkor  Major cause of death associated with kwashiorkor is INFECTION, since sufficient protein is required to maintain immune function  Symptom: edema (extension of the belly)  Associated with infection, as well as infection leading to death Micronutrient Malnutrition  “mild-to-moderate” malnutrition o We would see this in Canada  Deals with dietary quality  Deficiencies in Vitamins A, B, C, D, etc. o Example: lack of vitamin B causes rickets; bones doesn’t have sufficient minerals in the bones  Iodine  Iron  Ca  Zn  Micronutrient deficiencies are associated with low birth weight and poor infant neuro-behavioural development at birth o Example: growth stunting Quiz # 2: Protein calorie (or protein-energy) malnutrition is most correctly characterized as:  Inadequate dietary quantity and quality Nutrition, Poverty, and Intellectual Performance (see diagram and article) Malnutrition and Intellectual Development (Brown and Pollitt, 1996)  Earlier assumptions: 1. Poor nutrition is primarily an issue up to 2 yrs of age (when brain = 80% adult size) 2. Poor nutrition up to age 2 yrs hinders normal brain development, resulting in severe, lasting damage (irreversible)  Current Understanding: 1. With improvement in diet and health after 2 yrs, brain may exhibit “catch-up” growth (damage is not irreversible) 2. Brain growth can continue to be compromised by under-nutrition after 2 yrs 3. Intellectual impairment can result from more moderate malnutrition  THUS: importance of nutrition throughout childhood  Treat the brain and malnutrition in a longer span Infant Neurodevelopment  Maternal nutritional status during pregnancy influences neurobehavioural / cognitive and psychomotor development of infants (Brazelton Neonatal Assessment Scale)  Infant neurobehaviour linked to maternal intake of animal products, vitamin B6, B12 , iron, zinc (and weight) during pregnancy and lactation  Zn associated with infant autonomic stability, motor ability  Low vitamin B6 (levels in mum’s milk) associated with lower birth wt and infant more difficult to console/likely to cry  Mothers with better iron intake and status had infants with better neurobehavioural p
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