The Carbohydrates The Carbohydrates Sugars Starches and Sugars Starches and Fibers Fibers Chapter 4 Whitney Rolfes Understanding Nutrition 12th Edition Introduction Introduction Brain Muscles Glucose provides nearly all brain energy Glucose provide of all energy Glycogen muscles body tissues use Other from fat Carbs are Fattening mistaken thinking Whitney Rolfes Understanding Nutrition 12th Edition Know food exchange groups table Whitney Rolfes Understanding Nutrition 12th Edition CHO SOURCES CHO SOURCES ALL PLANT FOODS Whole grains Vegetables starchy and non starchy Legumes Fruits MILK MILK PRODUCTS Whitney Rolfes Understanding Nutrition 12th Edition Chemists View of Chemists View of Carbohydrates Carbohydrates Carbohydrate family Atoms and chemical bonds distinguishes differences Monosaccharides single CHO Disaccharides composed of pairs of monosaccharides Polysaccharides large molecules composed of chains of monosaccharides Whitney Rolfes Understanding Nutrition 12th Edition Breakdown Breakdown Monosaccharides most important in nutrition Chemical shorthand C H O Hexoses sugars w 6 carbon atoms 3 Types glucose fructose galactose Whitney Rolfes Understanding Nutrition 12th Edition Chemist s View of s View of Chemist Carbohydrates Carbohydrates Whitney Rolfes Understanding Nutrition 12th Edition Chemist s View of s View of Chemist Carbohydrates Carbohydrates Monosaccharides three kinds Same numbers and kinds of atoms Differing sweetness Glucose blood sugar Part of every disaccharide Fructose Sweetest of the sugars fruits honey Galactose Only in a few foods Whitney Rolfes Understanding Nutrition 12th Edition Chemist s View of s View of Chemist Carbohydrates Carbohydrates Disaccharides Pairs of the three monosaccharides Maltose two glucose units barley Sucrose glucose and fructose refined table sugar Lactose glucose and galactose milk sugar Whitney Rolfes Understanding Nutrition 12th Edition 2 important reactions 2 important reactions Condensation makes a dissach H2O Links two monosaccharides together and forms water Hydrolysis H O splits Breaks a disaccharide in two Whitney Rolfes Understanding Nutrition 12th Edition Chemist s View of s View of Chemist Carbohydrates Carbohydrates Whitney Rolfes Understanding Nutrition 12th Edition Polysaccharides Polysaccharides 1 Glycogen animal not a significant food source some in animals but not in plants not a dietary CHO Storage form of energy in the body Many glucose units 2 Starch plant Storage form of energy in plants Many glucose units Whitney Rolfes Understanding Nutrition 12th Edition Polysaccharides Polysaccharides 3 Fibers structure part of plant Differ from starches bond between monosch can t be broken by digestive enzymes Soluble fibers dissolve in water Insoluble fibers Functional fibers Resistant starches Phytic acid Whitney Rolfes Understanding Nutrition 12th Edition Soluble fibers fibers Soluble Forms gels Easily digested by bacteria in colon Oats barley legumes citrus fruits Protect against heart disease Protect against diabetes Whitney Rolfes Understanding Nutrition 12th Edition Insoluble fibers Do not dissolve in water Do not form gels Less fermented Whole grains bran veggies Promote regular bowel movements Alleviate constipation Prevent diverticular disease Whitney Rolfes Understanding Nutrition 12th Edition CHO Digestion CHO Digestion Absorption Absorption Starches polysaccharides disaccharides m s l monosaccharides g f g Liver converts galactose fructose into glucose Whitney Rolfes Understanding Nutrition 12th Edition Carbohydrate Digestion Carbohydrate Digestion Ultimate goal breakdown into small molecules Glucose for absorption and use Begins in 1 Mouth small amount Salivary Amylase from saliva Hydrolysis starch to shorter polysacch Very little digestion occur here Whitney Rolfes Understanding Nutrition 12th Edition Carbohydrate Digestion Carbohydrate Digestion 2 Stomach Stomach acid protein digesting enzymes inactivate amylase Stomach juices contain no digestive enzymes to digest CHO Role of fiber lingers delays gastric emptying satiety Whitney Rolfes Understanding Nutrition 12th Edition Carbohydrate Digestion Carbohydrate Digestion 3 Small intestine Most carbohydrate digestion takes place Pancreatic amylase comes thru pancreatic duct breaks down polysacchs to shorter glucose chains Whitney Rolfes Understanding Nutrition 12th Edition CHO Digestion Final step 3 Small intestine cont Specific disaccharide enzymes outer membranes of intestinal wall Maltase Sucrase Lactase At this point all polysach disachs monosach Whitney Rolfes Understanding Nutrition 12th Edition CHO Digestion CHO Digestion 1 4 hours after a meal all sugars most starches have been digested 4 Large intestine Fibers attract H O softens stools for passing Bacteria ferment some fiber H O gas short chain fa fatty acids Short chain fa can be used by colon for energy so fiber can provide small amount of enenrgy Whitney Rolfes Understanding Nutrition 12th Edition Whitney Rolfes Understanding Nutrition 12th Edition Carbohydrate Absorption Carbohydrate Absorption Mainly occurs in small intestine Active transport requires energy carrier Glucose Galactose Facilitated diffusion requires carrier Fructose Liver blood circulates from small intest Liver takes up converts fructose and galactose Whitney Rolfes Understanding Nutrition 12th Edition Monosaccharides the end products of carbohydrate digestion enter the capillaries of the intestinal villi Small intestine Monosaccharides travel to the liver via the portal vein In the liver galactose fructose converted to glucose Stepped Art Fig 4 11 p 105 Lactose Intolerance Lactase activity Highest immediately after birth Declines with age dramatically in childhood 30 people retain enough lactase Whitney Rolfes Understanding Nutrition 12th Edition Lactose Intolerance Symptoms of intolerance Not enough lactase lactose molecules not digested attracts H 0 Bloating abdominal distention gas diarrhea Whitney Rolfes Understanding Nutrition 12th Edition Lactose Intolerance Prevalence 30 50 million in US Genetically determined 80 Southeast Asians Native Americans 75 African Americans 70 Mediterranean people 50 Hispanic 20 Caucasians 10 Northern Europeans Whitney Rolfes Understanding Nutrition 12th Edition Lactose Intolerance Lactose Intolerance Dietary changes Manage dairy consumption rather than restriction Many can consume 6 gms lactose 1 2c Milk without symptoms Increase milk products gradually take w other foods in meals spread
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