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Judith E. Brown www.cengage.com/nutrition/brown Useful Facts about Sugars, Starches, and Fiber Unit 12 Prof. Albia Dugger • Miami-Dade College The Carbohydrates • Carbohydrates • Chemical substances in foods that consist of a simple sugar molecule or multiples of them in various forms • Primary ingredient of staple foods (pasta, rice, cassava, beans, bread) Three Types of Carbohydrates 1. Simple sugars 2. Complex carbohydrates (starches) 3. Total fiber Carbohydrate Sources • Simple sugars (left), starch and fiber (right) Carbohydrate Functions • Major source of energy • Recommended intake 45-65% of total calories • Simple sugars and complex carbohydrates supply 4 calories/gram • Dietary fiber indirectly supplies 2 calories/gram (when digested by bacteria in colon) • Other functions in immune and reproductive systems, blood clotting, DNA Alcohol • Alcohol (ethanol) and alcohol sugars have similar structures Simple Sugar Facts • Simple sugars (sugars) • Carbohydrates that consist of a glucose, fructose, or galactose molecule, or a combination of glucose and either fructose or galactose • Also includes high-fructose corn syrup and alcohol sugars Two Types of Simple Sugar • Monosaccharides • Consist of one sugar molecule • Glucose, fructose, galactose • Disaccharides • Consist of two monosaccharides linked together • Sucrose, maltose, lactose • Broken into monosaccharides by digestion Disaccharides Energy Production • Glucose is the only simple sugar the body can use to form energy • Fructose, galactose are converted to glucose • Excess glucose is converted to fat and glycogen • Body produces glucose by breaking down glycogen, amino acids, glycerol from fats • Cells in brain, blood, and kidneys require a constant supply of energy from glucose Glycogen • Glycogen • Storage form of glucose • Complex carbohydrate • Long chains of glucose molecules • Produced only by animals • Stored in liver and muscles Body’s Sources of Glucose Simple Sugar Intake • In US, total simple sugar intake averages 23% of total calories • 17% of total calories from added sugars • Sucrose • High-fructose corn syrup Simple Sugars in Foods • Added sugars in candy, beverages, cereals • Natural sugars in milk, fruit, some vegetables Nutrition Labeling of Sugars • Nutrition labels list total amounts of monoand diglycerides per serving under “sugars” • All simple sugars must be listed in order of weight in the ingredients Labeling Sugars What’s So Bad About Sugar? • Simple sugars provide only calories • Sweetened foods are often high in fat, low in nutrients • Problems associated with high sugar intake: • Increased blood triglycerides • Excessive calorie intake • Tooth decay Advice on Sugar Intake • Limit added sugars to 10% or less of total calorie intake Alcohol Sugars • Alcohol sugars (“polyols”) • Simple sugars containing an alcohol group in their molecular structure • Incompletely digested (~2 calories/gram) • Examples: • Xylitol, mannitol, sorbitol • Used as sweetening agents • Do not promote tooth decay Products With Alcohol Sugars Artificial Sweetener Facts • Artificial (non-nutritive) sweeteners • Not significant sources of energy or nutrients • 160 to 13,000 time sweeter than sucrose • Do not promote tooth decay Products with Artificial Sweeteners Artificial Sweeteners Artificial Sweeteners • Saccharin • First artificial sweetener (1800s) • 300 times sweeter than sucrose • Aspartame (Nutrasweet) • Contains amino acids phenylalanine, aspartame • 4 calories/gram • 200 times sweeter than sucrose Is Aspartame Safe? • Products containing aspartame must carry a warning for people with certain conditions • Phenylketonuria (PKU) • Genetic disorder • Lack of enzyme phenylalanine hydroxylase causes phenylalanine buildup in blood Safe Limits for Aspartame • Safe levels of aspartame set at 50 mg/kg body weight/day • Some individuals report sensitivity to small amounts Artificial Sweeteners cont. • Sucralose (Splenda) • Made from sucrose • 600 times sweeter than sucrose • Acesulfame K (Sunette, Sweet One) • Acesulfame potassium • 200 times sweeter than sucrose Artificial Sweeteners cont. • Neotame • Like aspartame, made from phenylalanine and aspartame, but not harmful to people with PKU • 7,000-13,000 times sweeter than sucrose • Rebiana (Reb-A, Truvia, Purevia) • Derived from herb stevia Stevia-Based Sweeteners Sweetness Rankings • Artificial and natural sweeteners, in order of sweetness Complex Carbohydrate Facts • Complex carbohydrates • Form of carbohydrate found in starchy vegetables, grains, dried beans, and many types of dietary fiber • The most common form of starch is made of long chains of glucose units Complex Carbohydrate Facts • Polysaccharides • Carbohydrates containing many molecules of monosaccharides linked together • 3 major types: starch, glycogen, dietary fiber • Oligosaccharides • Polysaccharides consisting of 3 to 10 monosaccharides Which Foods Have Carbohydrates? Which Has More Calories? • 4 oz baked potato • 122 calories • 3 oz lean hamburger • 239 calories US Fiber Facts • Fiber is low in calories, prevents constipation, and may lower risk of heart disease, obesity, and diabetes • Recommended intake 28-35 grams/day • Fiber intake by US children and adults is low: about 15 grams of fiber/day Good Sources of Fiber Good Sources of Fiber Types of Fiber • Edible fibers are classified based on source and effects on body processes • Functional fiber • Dietary fiber • Total fiber Functional Fiber • Functional fiber • Specific types of nondigestible carbohydrates that have beneficial effects on health • Examples: psyllium, pectin, gels, gums • Effects: • Feeling of fullness, slows glucose absorption, prevents constipation, decreases fat and cholesterol absorption Dietary Fiber • Dietary fiber • Naturally occurring, intact forms of nondigestible fiber in plants and “woody” plant cell walls • Contains nutrients and other plant substances • Found in oat and wheat bran; plant cellulose, fruits and vegetables, raffinose in beans Dietary Fiber In Wheat Bran Total Fiber • The recommended daily intake of fiber is based on total fiber • Total fiber • The sum of functional and dietary fiber Soluble and Insoluble Fiber • Soluble fibers combine chemically with water • Found in oats, barley, fruit, psyllium • Slows glucose absorption • Reduces fat and cholesterol absorption • Insoluble fibers do not combine chemically with water • Found in bran, some legumes • Same health benefits as soluble fiber Adding Fiber to Your Diet • Adding too much fiber to the diet too quickly can result in temporary side effects • Increase fluid intake along with fiber intake • Don’t add excessive fiber to children’s diets Carbohydrates and Blood Glucose • Some types of simple and complex carbohydrates in foods elevate blood glucose levels more than others • Important to people with insulin resistance and type 2 diabetes Key Terms • Insulin resistance • When cell membranes have reduced sensitivity to insulin, more insulin is required to transport a given amount of glucose into cells • Type 2 diabetes • High blood glucose levels due to the body’s inability to use insulin normally, or to produce enough insulin Glycemic Index • Carbohydrate-containing foods are classified by how much they increase blood glucose • Glycemic index • Measure of how much blood glucose is raised by a 50-gram portion of a carbohydrate-containing food, compared to 50 grams of glucose or white bread Glycemic Index of Foods • Some high glycemic-index foods: • Glucose, white bread, baked potatoes, jelly beans • Some low glycemic-index foods: • Fructose, xylitol, hummus, apples, all-bran cereal Low Glycemic Index Diets • Diets with low glycemic index carbohydrates: • Improve blood glucose control • Reduce elevated blood cholesterol and triglycerides • Increase beneficial HDH cholesterol • Decrease risks of type 2 diabetes, some types of cancer, and heart disease Carbohydrates and Your Teeth • Tooth decay did not become a problem until sugar became widely available • Tooth decay (dental caries, cavities) • Disintegration of teeth due to acids produced by bacteria in the mouth that feed on sugar Sugars From Starchy Foods • Enzymes in the mouth break down starches into simple sugars • ”Happy Tooth” symbol used in Europe to indicate foods safe for teeth Tooth Decay: More Than Sugar • Stickiness and frequent consumption of sugary/starchy foods increases tooth decay • • • • Eating sticky foods Eating sugary foods between meals Frequently sipping sweetened beverages Chewing sugary gum “Stickiness” Sugar and Tooth Decay • Sugar feeds bacteria that live in the mouth and secrete acids that dissolve teeth • Plaque • Soft, sticky, white material on teeth • Formed by bacteria Foods That Don’t Promote Decay Water Fluoridation • Addition of fluoride to community drinking water supplies reduces the incidence of tooth decay by 50% or more • Fluoride is also added to toothpastes, rinses and gels, and to protective sealants Baby Bottle Caries • Infants and small children who fall asleep while sucking a bottle may develop severe decay • Fluid pools around the upper front teeth