Energy Metabolism NTR 108 Objectives 1 Describe the metabolic pathways involved in energy metabolism 2 Describe the functions of the B vitamins 3 Define the risks factors associated with obesity 4 Describe the methods for measuring percent body fat 5 Describe treatment options for obesity Energy Metabolism Topics Metabolic pathways Vitamins Thiamine Niacin Riboflavin Pantothenic Acid and Biotin Minerals Chromium and Iodine Energy balance Obesity Risks Diagnosis Treatment Energy Metabolism PART 1 MACRONUTRIENT AND ALCOHOL METABOLISM Metabolism Anabolism Building body compounds by putting together smaller units Example storing triglycerides as fat Catabolism Breaking down the compounds to basic units for energy and excretion Example breaking down glycogen to release glucose which can be metabolized for energy Key definition ATP adenosine triphosphate high energy compound cells use for fuel Glucose Metabolism Sources of glucose 6 carbons From blood From glycogen in liver and muscle Metabolism Glycolysis glucose for energy 4 kcal gram Anaerobic without oxygen In cytosol of cells 2 ATP formed Lactic acid produced muscle fatigue Glucose Metabolism Pyruvic acid goes on to other pathways citric acid cycle Metabolism continued Aerobic oxygen needed In mitochondria of cells Ultimately 36 38 ATP formed CO2 formed no lactic acid Slower than anaerobic Glucose Metabolism Amino Acid Metabolism Metabolism carbon skeleton for energy or glucose Sources of amino acids From blood From intracellular protein 4 kcal g Anaerobic without oxygen Cytosol Mostly same as glucose Aerobic with oxygen Mitochondria Mostly same as glucose Almost all amino acids can be converted to glucose Urea from nitrogen formed in liver Lipid Metabolism Sources of fatty acids From blood From cellular triglycerides Metabolism fatty acids for energy 9 kcals g Aerobic requires oxygen In mitochondria With glucose Beta oxidation is major pathway products go to citric acid cycle Complete oxidation to CO2 Lots of energy formed ATP Example palmitic acid 16 carbons yields 129 ATP Without glucose Ketones formed Ketogenesis in liver Some energy ATP Send to peripheral tissues for energy Alcohol Ethanol Metabolism 7 kcal g 5 of US caloric intake Metabolism Metabolized in the liver by ADH alcohol dehydrogenase To fatty acids or ATP Acetaldehyde toxin is intermediate CO2 released Sources National Health and Nutrition Examination Survey 2007 2010 Available at http www cdc gov nchs nhanes htm Energy Metabolism PART 2 VITAMINS INVOLVED IN ENERGY METABOLISM Vitamins Involved in Energy Metabolism Directly or indirectly vitamins are involved in energy metabolism Needed for conversion of glucose fatty acids amino acids and alcohol to chemical intermediates Are co enzymes used in generation of ATP Vitamins Involved in Energy Metabolism Vitamins Involved in Energy Metabolism Vitamins Involved in Energy Metabolism Coenzyme for energy metabolism carbohydrate and amino acid metabolism Plays a role in the production of neurotransmitters Thiamin Definition classification Water soluble vitamin Also called B1 Functions Deficiency signs symptoms Beriberi Reduced cognitive function Heart failure Fatigue Paralysis Dementia and amnesia 3rd most common dementia in US Due to alcohol excess Overall weakness Vitamins Involved in Energy Metabolism Thiamin continued Groups at risk for deficiency Alcoholics Thiamin lost through liver Polished rice as main food Thiamin lost during removal of rice bran Same for wheat white flour Added back in US through enriched flour Malabsorption AIDS Dietary sources Whole grains with germ Enriched flour Green leafy vegetables Beans and legumes Pork Special notes No toxicity excess lost in urine Need increases with an increase in physical activity Lost in cooking water most water soluble vitamins Vitamins Involved in Energy Metabolism Coenzyme for energy metabolism carbohydrate and fat metabolism Riboflavin Definition classification Water soluble vitamin B2 Functions Deficiency sign symptoms Weakness Fatigue Cracks at corners of mouth Magenta tongue Groups at risk for deficiency Alcoholics Liver disease Diabetics Dietary sources Enriched flour products Milk Green leafy vegetables Special notes Very sensitive to light can be lost in glass milk bottles Vitamins Involved in Energy Metabolism Coenzyme for energy metabolism carbohydrate and fat metabolism Niacin Definition classification Water soluble vitamin Functions Fatty acid synthesis DNA replication Deficiency sign symptoms Pellagra 4 D s Dermatitis Diarrhea Dementia Death Vitamins Involved in Energy Metabolism Niacin continued Groups at risk for deficiency Alcoholics Low protein intake Can be made from an EAA tryptophan Dietary sources Whole grains Enriched flour Meat and fish Made in liver from tryptophan Special notes Niacin can be used as a hypercholesterolemia drug lowers blood cholesterol Niacin can be toxic at high levels Flushing Liver damage Vitamins Involved in Energy Metabolism Coenzyme energy metabolism especially important for fat Pantothenic Acid Definition classification Water soluble vitamin Functions Fatty acid synthesis Deficiency sign symptoms Weakness Fatigue Groups at risk for deficiency Deficiency very rare Malabsorption Dietary sources Pan found everywhere Whole grains Meat Milk Vitamins Involved in Energy Metabolism Coenzyme for energy metabolism involved in metabolism of all macronutrients Biotin Definition classification Water soluble vitamin Functions Deficiency sign symptoms Red scaly rash around eyes nose and mouth Lethargy weakness Groups at risk for deficiency Deficiency very rare People that eat a lot of raw egg whites Contain a protein that binds biotin and makes it unable to be absorbed Dietary sources Meat Egg yolks Nuts Legumes peanuts Some produced in intestine Energy Metabolism PART 3 MINERALS INVOLVED IN ENERGY METABOLISM Minerals Involved in Energy Metabolism Chromium Iodine Iron copper and zinc covered in the module on hematopoietic system Minerals Involved in Energy Metabolism Enhances ability of insulin to move glucose from blood into cells Chromium Definition classification Trace mineral need very little Functions Deficiency sign symptoms Rise in blood glucose levels Groups at risk Deficiency uncommon in the U S Dietary sources Whole grains Mushrooms Nuts Dark chocolate Special notes No evidence for supplement claim to enhance muscle mass reduce body fat A common supplement is chromium picolinate Organ damage Minerals Involved in Energy