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We already know… Carbohydrates • CHO • Energy yielding: 4 kcal/g • Macronutrient Chapter 4 What foods is it in? • Grains • Vegetables • Especially starchy ones! • • • • Fruit Milk Legumes Sugary foods CHO Classifications • Complex carbohydrates aka Polysaccharides: large chains of monosaccharides • Starch • Glycogen • Some fibers CHO Classifications • Simple carbohydrates: sugars • Monosaccharides: single sugars • Disaccharides: pairs of monosaccharides Sugars: Monosaccharides • Glucose: (aka dextrose) the principle building block of CHO • Component of di- and poly• aka blood sugar--the chief energy source for the body's cells 1 Sugars: Monosaccharides • Fructose: the sweetest of the sugars • aka fruit sugar • in fruits, honey, also made in highfructose corn syrup CHO: Building and Breaking • CHO are linked together through condensation (water is removed) • Hydrolysis (water is added) reactions break down CHO Sugars: Disaccharides • Maltose: not in many foods • a product of CHO breakdown • During digestion • During fermentation Sugars: Monosaccharides • Galactose: almost never alone, usually tied to gluc in lactose Sugars: Disaccharides • Maltose (Glucose + Glucose) • Sucrose (Glucose + Fructose) • Lactose (Glucose + Galactose) Sugars: Disaccharides • Sucrose: table sugar • made from either sugar cane or sugar beets • Refined into brown, white, etc. sugars 2 Sugar & Health CAN CAN’T • Aggravate BG issues • Have excess kcal • Increase blood triglycerides • Cause dental caries • Cause Diabetes • Cause Hyperactivity Sugars: Disaccharides • Lactose: milk sugar • the CHO source in breast milk • Lactose --> glucose + galactose • Requires enzyme lactase • Shortage of lactase causes lactose intolerance Lactose Intolerance: Causes • • • • • • Genetics Medications GI tract damage Prolonged diarrhea Low dairy intake: “Use it or lose it” Common with aging Sugar vs Honey • • • • sugar = sucrose honey = fructose + glucose + sucrose More energy dense than table sugar DO NOT feed to infants-botulism risk Lactose Intolerance • Not the same as milk allergy • Undigested lactose molecules attract water (osmosis) • Sx: bloating, abdominal pain, diarrhea AND • Gut flora uses lactose as fuel • Sx: gas, more bloating, more pain Lactose Intolerance • Tx is individualized • Yogurt and cheese often ok-- bacteria ferment the lactose during manufacturing • Can replace lactase enzyme using "Lactaid" tablets or drops. • Or can use fortified soy milks. 3 Complex CHO • • • • Complex CHO ≠ high fiber Polysaccharides Starch: plant storage form of CHO Main sources: grains (wheat, corn, rice), tubers (potatoes, yams), legumes (beans, peas) Glycemic Response • How much a food affects BG • Glycemic Index: ranking of foods p.116 • More than just the CHO affects GR! CHO is a CHO is a CHO • All CHO becomes glucose BUT starch takes longer to digest than sugars • Saliva & Pancreatic juice breaks down the polysaccharides • Intestinal juices breaks down disaccharides: • maltase, sucrase, lactase • monosaccharides go into the blood • In liver, fructose and galactose get converted into gluc CHO: Brain’s favorite fuel • Glucose is used to fuel the body’s cells • Especially nervous system, RBC • Extra is then stored… • Better bet--stick to high fiber CHOs Complex CHO • Glycogen: animal (so OUR) storage form of gluc, but not really found from food • highly branched glucose chains--easy to hydrolyse • when gluc is plentiful (like after a meal) liver turns the excess into glycogen • Liver stores 1/3, for use when blood gluc drops Glycogen • Stores only last for a few hours • Glycogen “holds” onto water • Early low carb diet success • Only lasts a few hours • Muscles store the other 2/3, but keep it for their own work 4