The Biology of Malnutrition The cycle of malnutrition How and where to break the cycle is the issue The focus of intervention is now on the Lifecycle or life course Types of Malnutrition Overnutrition Secondary malnutrition Micronutrient malnutrition Protein Calorie malnutrition Overnutrition Too many calories leading to obesity diabetes hypertension and cardiovascular disease Transition diets now a consideration of WHO due to increase worldwide in chronic disease due to dietary change Overnutrition On a global basis 79 of all deaths attributable to chronic disease are already occurring in developing countries Public health implications are staggering Overnutrition following fetal malnutrition has also been linked to chronic disease risk in adulthood Secondary Malnutrition Condition that prevents proper digestion or absorption Often accompanies and exacerbates other types of malnutrition Secondary Malnutrition causative conditions Loss of appetite Alteration of normal metabolism during infection fever HIV AIDS Prevention of nutrient absorption Diarrheal infection causing changes in GI epithelium Secondary Malnutrition causative conditions Diversion of nutrients to parasitic agents themselves Hookworms tapeworms schistosome worm Malaria Children with Intestinal Parasites courtesy of WHO Prevention of nutrient diversion Sanitary waste disposal and clean water important in reducing secondary malnutrition Prevention of transmission of parasites and diarrheal diseases Hookworm acquired by walking barefoot over contaminated soil Other roundworm infections use oral fecal route Prevention of nutrient diversion Soap an important factor in nutritional status Education of women extremely important in this regard Micronutrient Malnutrition Dietary Deficiencies of Vitamin A Iodine Iron Others Zinc vitamins D C and Bs Protein Calorie Malnutrition More food needed for normal growth health and activity Rarely have protein deficiency without caloric deficiency due to the nature of the food supplies exception seen with cassava and plantain as staples Role of calories Involuntary use breathing blood circulation digestion maintaining muscle tone and body temperature Physical activity Mental activity Fighting disease Growth Role of protein For building cells that make up muscles membranes cartilage and hair Carrying oxygen Nutrient transport Antibodies Enzymes needed for most chemical reactions in the body What happens to people when they have inadequate amounts of food and nutrients Metabolic changes Physiologic changes Psychological changes Metabolic Response to Starvation Hunger subsides after 2 3 days Defecation ceases after 3 4 days Urine output drops after 1 week in the majority of people to 100 700 ml day Blood glucose levels drop to 35 to 65 mg dl without clinical signs of hypoglycemia Nausea occurs in about 1 3 from ketone production from body fat breakdown Metabolic Response to Starvation Serum electrolytes do not change Renal conservation occurs promptly Rarely see low potassium in prolonged fast Metabolic Response to Starvation Negative nitrogen balance 1 st 5 to 7 days 12 to 15 grams of nitrogen per day is excreted in the urine based on 1800 kcal daily needs Skeletal muscle is catabolized to produce glucose gluconeogenesis using about 75 grams per day of protein This is equal to lb of wet tissue per day About 160 gm per day of body fat is also used Metabolic Response to Starvation Negative nitrogen balance Gradually slows so that at about 1 month 2 4 grams of nitrogen is loss per day Skeletal muscle catabolism decrease significantly Only for cells that have to have glucose Central nervous system Red blood cells White blood cells Metabolic Response to Starvation Gradual shift in metabolic fuels First glucose is produced from protein breakdown to provide energy Then fat breakdown and metabolism provides ketones for all tissues except CNS RBC and WBC Brain will eventually use ketones but red blood cells have no mitochondria so must use glucose Serum fatty acid levels increase Serum albumin is normal until late in starvation Production of Ketones Metabolism Metabolic Response to Starvation Hormonal changes Plasma insulin decreases Plasma cortisol and growth hormone stay the same and glucagon increases These changes are responsible for the mobilization and oxidation of fat stores Changes in sympathetic nervous system and metabolism of thyroid hormone lowers basal metabolic rate Metabolic Response to Starvation Weight loss First week 0 7 to 1 3 kg per day much of which is slat and water loss After the first week 0 3 to0 5 kg day Basal Metabolic Rate and Total Energy Expenditure decrease in prolonged starvation See decreased activity increased sleep Decrease in body temperature Classic study by Keyes described physical and psychological changes during a period of semi starvation Traditionally used to describe what happens during dieting Perhaps should think about traditional stereotypes of the poor in relationship to the findings of this study Keyes Study Impetus realization WWII would be over soon and food relief was going to be necessary needed data Subjects 32 men Conscientious objectors Ages 25 5 3 5 years Time period 11 19 44 to 1 20 45 Keyes Study Diet 12 weeks of baseline diet ad lib Normal diet of 51 carbohydrate 13 protein 32 fat 24 week semi starvation diet 12 weeks of rehabilitation normal diet Keyes Study 24 week semi starvation diet Consisted of food designed to represent the types of foods available in European famine areas whole wheat bread potatoes cereals considerable amounts of turnips and cabbage token amounts of meat and dairy products About 1600 kcal per day 71 carbohydrate 12 protein and 17 fat Served in 2 meals per day at 8 30AM and 5 PM Keyes Study Activity Assigned specific tasks such as general maintenance laboratory assistance shop duties and desk work about 15 hours per week Educational programs about 25 hours per week Walked 35 km out of doors per week and were on a treadmill for hour Keyes Study Body changes Body weight decreased about 25 From mean of 69 4kg BMI 21 4 to 52 6 kg BMI 16 3 Weight loss decreased progressively and nearly reached a plateau at the end of the semi starvation period Subjects adjusted their energy expenditure to reach a balance after 24 weeks at 45 of the ad lib diet Keyes Study Adaptations Adaptation accompanied by a loss of active tissue Relatively high loss of lean body mass Body fat loss made up about 1 3 of the weight change Keyes