Marissa Ashcraft Carbohydrate organic compounds CH2O Basic structure is a simple sugar Can be assembled to make more complex molecules Two Categories Simple Complex Simple Sugars Monosaccharides Glucose dextrose Plays key role in foods and in body Supplies energy to cells blood sugar fuel for brain Found in fruits vegetables honey Fructose Galactose Levulose or fruit sugar Occurs naturally in fruits and veggies Used as an additive in processed foods Part of lactose in milk Rarely occurs as a monosaccharide in food Simple Sugars Disaccharides Disaccharides two linked sugar units Sucrose glucose fructose Made from sugar cane and sugar beets Lactose glucose galactose Maltose glucose glucose Found in germinating cereal grains Product of starch breakdown Complex Carbs Oligosaccharides Polysaccharides Starch Short chains of CHO 3 30 sugar molecules Most common are raffinose and stachyose Body can not break these down dietary fiber in adults Long chains of glucose units Amylose straight chains Amylopectin branched chains Found in grains starchy vegetables legumes Glycogen Highly branched chains of glucose units Storage form of CHO in living animals In liver and skeletal muscle mainly Dietary Fiber nonstarch long chains Provides structure to plants Dietary Functional Total Fiber Dietary intact and intrinsic in plants Functional isolated CHO with beneficial effects Indigestible chains of monosaccharides Soluble fiber has thickening properties Insoluble fiber moves quickly thru digestive system Fiber 1 Marissa Ashcraft Carbohydrate Digestion and Absorption Salivary amylase digests starch into shorter polysaccharides and maltose Very little digestion in stomach Stomach acid denatures amylase Fiber provides feeling of fullness delays emptying Most digestion in small intestine Pancreatic amylase completes starch digestion Enzymes in brush border split disaccharides for absorption End products of carbohydrate digestion Glucose fructose galactose Absorbed into bloodstream Fibers are not digested are excreted in feces Digestive Enzymes Highly specific to specific carbohydrates Inability to break down specific CHO means they are undigested Remain undigested in large intestine Bacteria partially ferment or break down to oligos yielding gas Lactose intolerance cannot break lactose Absorption and Metabolism of Carbohydrates Absorbed into mucosal cells by active transport and facilitated diffusion Once in villi monosaccharides travel to the liver via the portal vein where galactose and fructose are converted to glucose preferred fuel Liver stores and releases glucose as needed to maintain constant blood glucose Glucose taken up by cells broken down into CO2 and water and ATP is released levels Storing Glucose After eating immediately use some glucose to maintain blood sugar Store glucose as glycogen in liver and muscle Insulin and glucagon regulate blood sugar closely Both hormones produced by pancreas If glycogen stores are depleted body makes glucose from protein Brain cells and developing RBC s require constant supply of glucose Dietary CHO spares body protein CHO needed to completely break down fat and prevent build up of ketones in the Organic compounds a carbon oxygen double bond bound to two hydrocarbons Main precursor is acetyl CoA Pyruvate and fructose are two examples of ketones Acetone acetoacetate and betahydroxybutyrate are ketone bodies Result from consumption of a low carb diet as a by product of incomplete fat Blood becomes slightly acidic may cause dehydration Their synthesis is avoided if consumption of CHO is adequate 250 grams DV is blood ketosis Ketone Bodies and Ketosis breakdown 300 grams 2 Regulation of Blood Glucose Pancreas Insulin Marissa Ashcraft The key that unlocks cells to allow blood sugar to enter Also stimulates liver muscle to store glucose as glycogen Pancreas Glucagon Stimulates breakdown of glycogen into glucose for use by cells Also stimulates synthesis of glucose from protein Adrenal glands Epinephrine Carbohydrates in the Diet Recommended intake 45 65 of calories DV Daily Value for 2 000 kcal 300 grams Dietary Guidelines and MyPyramid I Reduce intake of added sugars Increase complex CHO intake Grains especially whole grains Moderate Sugar Intake nutrients Nutritive Sweeteners Crowds out foods with more concentrated sources of essential Digestible CHO provide energy Natural unprocessed honey maple syrup Refined mono and disaccharides extracted from plant foods Increasing Fiber Intake Fiber 10 13 gm 1000 kcals 20 35 gm for adults To increase fiber intake eat more breads cereals pasta rice fruits vegetables legumes and whole grains Eat fruits and vegetables with the peel if possible as this is high in fiber Choose high fiber cereals 3 gm fiber serving Effects of Excess Fiber With all of its health advantages high fiber intake can cause problems especially in those who drastically increase their fiber intake in a short period of time A sudden increase in fiber can cause increased intestinal gas and bloating Water intake should be increased along with fiber intake to prevent constipation Sugar in Children Because honey and Karo syrup may contain Clostridium botulinum botulism spores they should never be fed to Infants younger than one year of age Infants do not produce much stomach acid which allows spores to germinate in the GI tract Dietary sugar does not cause adverse behavior Diabetes Mellitus Body s inability to regulate blood sugar adequately Either too little insulin or resistant to effects Type 1 pancreas produce inadequate insulin need shots Type 2 insulin resistance obesity plays a role need diet and exercise oral medications insulin injections Cells have no access to blood sugar Liver tries to make glucose from protein and fat creating acidity ketones Kidneys unable to reabsorb glucose Glucosuria excess glucose excretion in urine 3 Ranks CHO based on their rate of glycemic response Scale from 0 to 100 Higher values Foods that cause the most rapid rise in blood sugar Pure glucose is the reference of Glycemic Index 100 Marissa Ashcraft Glycemic Index Glycemic Index influenced by Amount eaten Fiber and fat content Food preparation Carbohydrate Simple monosaccachrides galactose glucose and fructose disaccharides lactose sucrose and maltose Complex starch fiber and glycogen Lactose maldigestion inability to properly absorb the milk sugar lactose due to a decreased in the amount of lactase in your digestive tract Fiber occurs naturally in plant based food