Starvation ppt

Protien metabolism of starvation and protien sparing

1. STARVATION Presented by , Lekhana H SRN – R21HD019 3 rd sem Msc BC

2. Starvation in humans is the deprivation of any or all of the elements necessary for appropriate nutrition. Conditions for developing Starvation - Food Scarcity (Natural Calamities , Draughts, Floods and Famines) Extreme Poverty Lost in Sea routes for long durations Clinical Conditions: Major Surgeries, Severe Burns. Desire to loose rapid weight Political Issues: Hunger Strikes

3. No entry of exogenous food constituents Body in starvation is deprived of: Calories (Carbs and Lipids) Building blocks (Proteins) Growth Factors(Vitamins and Minerals) Protectors (antioxidants) ( During Starvation the body is under Metabolic Stress. Due to deprivation of only Food: 3 to 4 Weeks Longer up to 65 days Deprivation of water alone then survival is only for few days Less than a week Antioxidants) Features of Starved body

4. During starvation No exogenous Food source ingested Food Nutrients get deprived Body is in an emergency condition Metabolic stress is developed Body manages and adapts to live on the endogenous fuel stores. Alterations in metabolic/biochemical processes

5. Protein Metabolism During Starvation Catabolism Of Muscle Proteins increased. During the first few days of fasting, there is a rapid breakdown of muscle protein, providing amino acids that are used by the liver for gluconeogenesis. Because muscle does not have glucagon receptors, muscle proteolysis is initiated by a fall in insulin and sustained by a rise in glucocorticoids. Trans-deamination reaction of Amino acids is increased. To release Glucogenic amino acids(Alanine and glutamine). Ammonia Detoxification and Urea production increased initially and decreased as Starvation phase prolongs. Body is in negative Nitrogen Balance. Concentration of Functional Proteins Decreases. Glucose-Nitrogen Ratio Increased In Starvation.

6. Consequences Of Starvation Severe Malnutrition Damages and affects vitality of Important Internal Organs Decreased BMR Night blindness (Vitamin A deficiency) Scurvy (Vitamin C deficiency) Irregular Menses Constipation Low Immunity Bone Loss Anaemia (Iron and Protein deficiency) Fatigue Dehydration Water Electrolyte Imbalance High Blood Pressure Brain Defects Death

7. Starvation ensues when the fat reserves are completely exhausted and protein is the only fuel source available to the body. Thus, after periods of starvation, the loss of body protein affects the function of important organs, and death results, even if there are still fat reserves left unused . The aim is to replace glucose catabolized by patients, and spare his tissue proteins by reducing the need for gluconeogenesis. The conventional metabolic care of severely ill patients include the administration of atleast , 100g of carbohydrates per day by the peripheral intravenous infusion of 5% dextrose in water. Protein sparing tReatment

8. Death associated with lack of food occurs when 30-50% of the body proteins are depleted. Obviously, the ideal situation for an obese dieter would ‘be an ability to use only fat and therefore totally spare body protein. Nitrogen excretion falls progressively during total fasting in obese subjects, most rapidly in the first 2 week and then very slowly thereafter. Nitrogen loss occurs as urea and ammonium. Factors in progressive protein “sparing” that develops with fasting, including a fall in insulin levels, an increase in fatty acid levels, an increase in ketone body levels (as an energy source), and an alteration in levels of circulating amino acids .

9. Important mechanisms for protein-sparing when FFAs and ketone bodies are available as fuel are inhibition of key enzymes for glycolysis (pyruvate dehydrogenase) oxidation of BCAA (BC 2-oxo-acid dehydrogenase) by a high acetyl-CoA/ CoASH ratio. In starvation, the kidney excretes excess hydrogen ions as ammonia from glutamine and glutamate, a process also leading to glucose production, and the kidney becomes a gluconeogenetic tissue. Thus, metabolic adaptation to starvation allows us to survive up to 2 months without food .

10. Starvation is used to treat severe human obesity but may be dangerous due to excessive loss of body protein. Obese humans when starving use fat and spare protein as effectively as those animals that spontaneously undergo prolonged fasting after accumulating large fat reserves.

11. references The Metabolic Events of Starvation Lecturers: CHRISTOPHER D. SAUDEK, M.D New York, New York PHILIP FELIG, M.D. New Haven, Connecticut Lippincott’s Illustrated Reviews: Biochemistry Sixth Edition Protein wasting due to acidosis of prolonged fasting M. C, HANNAFORD, L. A. LEITER, R. G. JOSSE, M. B. GOLDSTEIN, E. B. MARLISS, AND M. L. HALPERIN Department of Medicine, University of Toronto. The metabolic effects of fasting and surgery Jonas Nygren* MD, PhD Associate Professor, Senior Consultant Surgeon Centre of Gastrointestinal Disease, Ersta Hospital and Karolinska Institutet , P.O. Box 4622, 116 91 Stockholm, Sweden Metabolism during Fasting and Starvation: Understanding the Basics to Glimpse New Boundaries Moacir Couto de Andrade Júnior1,2* Starvation as treatment for obesity: The need to conserve body Protein , Yvon Le Maho , Jean-Patrice Robin, and Yves Cherel

12. THANK YOU