Carbohydrates 4kcal gram hydrate of carbon Stored as glycogen but is limited to certain tissues in a limited capacity as fat Primary fuel for CNS and RBC dietary Cho is provided by photosynthesis All monosaccharaides have the same formula C6H12O6 milk sugar in lactose converted to glucose at certain organs Glucose Most important fuel Major monosaccharide in body Also known as dextrose blood sugar Breakdown of starches and sucrose Galactose Not often ingested monosaccaride Fructose Very sweet Doesn t increase glucose Most from HFCS Monosaccharaides Increases blood lipids Disaccharides From starch Maltose Table sugar Sucrose Milk sugar Lactose Polysaccharides complex CHO Glucose found in all molecules 2 monosaccharides usually 100s to 1000s Starch Amylose Amylopectin digested more quickly Made in plants Glucose found exclusively Dietary Fiber Made in plants not digestible Glucose found Indigestible polysaccharide Body cannot break bonds Insoluble or Non fermentable Fiber Cellulose hemicellulose lignin not fermented by bacteria in colon bulking shorting GI transit time Soluble or Viscous fiber Gum pectin mucilage fruit vegetable rice bran psyllium seed used as food additive slows stomach emptying lowers blood glucose and cholesterol Glycogen Animals Glucose found exclusively Plants have mixture of amylose 20 and amylopectin but proportions differ Structural differences affect blood glucose Animals have glycogen certain organs store it helps to regulate blood glucose during delay between meals Functional Fiber Food Total Fiber dietary fiber added functional Found in bananas garlic wheat rye tomato Prebiotics Fructooligiosaccharides FOS Short chain CHO Microbiome Dental caries occur when bacteria of the oral cavities form calories on teeth plaque Without brushing flossing bacteria metabolize CHO in mouth and create acid Acid dissolves tooth enamel and underlying structures of the teeth and gums Nutritive provide calories and Non Nutritive Sweeteners no calories artificial High Fructose Corn Syrup Made from corn 55 fructose Cornstarch glucose acid and enzymes fructose Improved shelf stability food properties 60g person y 1000 increase in HFCS between 1970 and 1990 Obesity and overweightness paralleled HFCS consumption Alternative or Non Nutritive Sweeteners Different additives have different sweetness chemical stability sensory properties some have kcal but are used at trivial quantities in foods PKU is genetic disorder attributed to defective gene that produces phenylalanine hydroxylase Aspartame contains this First produced in late 1800s 180 200x sweeter than sucrose FDA no risk to humans Studies in rats lead to bladder cancer New food label will require added sugars to be labeled Aspertame Saccharin Carbohydrate Digestion Cooking Softens fibrous tissues Easier to chew and swallow Mouth Salivary amylase Further breakdown glucose Initiates CHO digestion No CHO absorbed however SMALL INTESTINE Site of CHO absorption Pancreatic juices bicarbonate pancreatic amylase digestion of starch continue to break it down and form disaccharides Enterocyte disaccharides Sucrase Sucrose glucose fructose Maltase Maltose originates from starch glucose glucose Galactose and fructose converted to glucose at the liver Lactase Lactose glucose galactose CHO Digestive Disorder Lactose Intolerance Prevalence increases with age begins in childhood About 25 of Americans African Americans American Indians and American Asians Two Problems production of acid and gas diarrhea Solution omit dairy lactose substitute cheese and yogurt Lactaid Monosaccharaides into body Glucose and Galactose active transport ATP energy is used carrier transporter Fructose facilitated transport carrier transporter but no ATP Delivered to the liver by hepatic portal vein from small intestine Fate of Hepatic Glucose Following Absorption CHO digestion and absorption highly efficient minor amounts fermented in colon Liver transforms monosaccharaides into glucose release glucose into bloodstream store as glucose store as fat least likely because only stores like this when consumed in excess Functions of CHO Supplies energy critical for RBC and brain Spares protein from catabolism Prevents ketosis results from excess breakdown of fat into ketone bodies could affect acid base balance Regulation of blood glucose liver secretes into blood pancreatic hormones control excursions in blood glucose insulin and glucagon Hyperglycemia immediately after eating blood glucose level increases insulin released Hypoglycemia hours after eating blood glucose drops glucagon is released Glucagon instructs liver to make new glucose and breaks down glucose Most insulin 1 hour after eating Most Glucagon 3 hours after eating Pancreas produces both Insulin lowers blood glucose by actions at liver muscle and adipose reduce gluconeogenesis Glucagon raises blood glucose by actions at liver and muscle increases glycogenolysis increases glycogenesis Epinephrine Adrenaline also regulates blood glucose but during Fight or flight response rapid breakdown glycogen rapid increase in blood glucose Diabetes Hypoglycemia leads to low blood sugar reactive hypoglycemia secretion of insulin usually doesn t occur often fasting hypoglycemia occurs 2 4 hours after eating meal possibly due to over usually caused by pancreatic cancer leads to overproduction glucose intolerance Type 1 pancreas doesn t produce insulin auto immune genetic disease tend to be excessively lean daily insulin injection needed Type 2 pancreas produces insulin but it doesn t work well at tissues excess blood insulin typically accompanied by obesity insulin sensitizing drugs needed weight loss sometimes insulin Glycemic index ratio of blood glucose response to a given food relative to a standard CHO meal High Glycemic Index Hyperinsulinemia increase blood triglycerides and liver fat accumulation increase fat deposits and artery clotting rapid return of hunger insulin resistance develops Daily Intake of Simple Sugars Often added to food or beverages Dental caries Low nutrient density and high energy density Dietary Fiber Health Recommendations are 25 35 g d for adults americans 12 15 g d Improves bowel health regularity and decreases hemorrhoid risk Decreases risk of obesity low kcal and promotes satiety Soluble fiber slows glucose absorption better blood glucose control Lowers CVD risk by lowering blood cholesterol decreases absorption of cholesterol decreases cholesterol synthesis in liver increases bile acid
View Full Document
Unlocking...