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Chapter 4 presents the following content: What are carbohydrates?simple sugars, complex carbohydrates, carbohydrate digestion and absorption, carbohydrates and glucose in the body, the role of carbohydrates in our diet, carbohydrates and health,...
Chapter Carbohydrates : Simple Sugars and Complex Chains What Are Carbohydrates? • • Sugars, starches, and fibers Major food sources: Plants – • Produced during photosynthesis Two main carbohydrate types – Simple (Sugars) – Complex (Starches and Simple Sugars • Monosaccharides – Glucose – Fructose – Galactose Simple Sugars • Disaccharides: Consist of two monosaccharides linked together – Sucrose – Lactose – Maltose Monosaccharides • Glucose – Most abundant simple sugar in nature – Also called dextrose – Gives food a mildly sweet flavor – Usually joined to another sugar in foods – Provides energy to body cells • Body closely regulates blood sugar levels Monosaccharides • Fructose – Also called levulose or fruit sugar – Tastes the sweetest of all the sugars – Occurs naturally in fruits and vegetables – Found in fruits, honey, and corn syrup Monosaccharides • Galactose – Rarely occurs as a monosaccharide in food – Usually bonds to glucose to form lactose • Primary sugar in milk and dairy products Disaccharides • • Sucrose: glucose + fructose – “Table sugar” – Made from sugar cane and sugar beets – Listed as sugar on food labels Lactose: glucose + galactose – “Milk sugar” – Found in milk and milk products Disaccharides • Maltose: glucose + glucose – “Malt sugar” – Seldom occurs naturally in foods – Product of starch breakdown – Found in germinating cereal grains Complex Carbohydrates • Chains of two or more sugar molecules – Oligosaccharides • • – Three to ten sugar molecules Examples sources: dried beans, peas, and lentils Polysaccharides • • Long chains of monosaccharides Structural differences affect how they behave in water and with heating Carbohydrates and Glucose in the Body • Glucose is our primary fuel – Needed to burn fat efficiently – When we eat food, our bodies • • Immediately use some glucose to maintain normal blood glucose levels Store excess glucose as glyocgen in liver and muscle tissue Carbohydrates and Glucose in the Body • Using glucose for energy – Liver glycogen • – Maintains normal blood glucose levels Muscle glycogen • Fuels muscle activity Carbohydrates and Glucose in the Body • Sparing body protein – • Adequate carbohydrates prevent body from making glucose from body proteins Preventing ketosis – Ketone bodies ketosis dehydration – Body needs a minimum of 50 to 100 grams of carbohydrate/day to prevent ketosis Carbohydrates and Glucose in the Body • Regulating blood glucose – To maintain an adequate supply for cells – Controlled by hormones • Insulin – • Glucagon – • Key “unlocking” body cells and allowing glucose to enter and fuel them Breaks down glycogen to glucose Epinephrine – “Fight-or-flight” hormone Carbohydrates and Glucose in the Body • Regulating blood glucose – Glycemic index • • Foods vary in their effect on blood glucose levels Index measures the effect of food on blood glucose levels The Role of Carbohydrates in Our Diet • Recommended Carbohydrate Intake – RDA = 130 grams per day – Dietary Guidelines • • • • “Reduce the intake of added sugars” AMDR for added sugars = < 25% of daily energy intake Choose whole grains, vegetables, fruits, and cooked dried beans and peas Consume > ½ of all grains as whole grains The Role of Carbohydrates in Our Diet • Current Consumption: How much are we eating? – AMDR = 45–65% of kcal – Average American adult = 49–50% of kcal – 13% of population has added sugar intake > 25% of kcal • • High soft drink consumption Milk consumption and vitamin and mineral quality of diet is declining The Role of Carbohydrates in Our Diet • Choosing Carbohydrates Wisely – • Increase fruit, vegetables, whole grains, low-fat milk Strategies – Eat peel fruit/vegetables – Eat legumes – Choose brown rice – Choose high-fiber cereal The Role of Carbohydrates in Our Diet • • High intake of foods rich in dietary fiber offers many health benefits, including reduced risk of – Obesity – Type diabetes – Cardiovascular disease – Gastrointestinal disorders Increase fiber intake gradually while drinking plenty of fluids Carbohydrates and Health • Fiber and obesity – • Fiber and type diabetes – • Better control of blood glucose Fiber and cardiovascular disease – • Possible role in weight control Can lower blood cholesterol levels Fiber and gastrointestinal disorders – Healthier gastrointestinal functioning Carbohydrates and Health • Negative effects of excess fiber – Gradual intake and increased water consumption – Can bind small amounts of minerals Carbohydrates and Health • Moderating sugar intake – Use less added sugar – Limit soft drinks, sugary cereals, candy, ice cream, and sweet desserts – Choose fresh fruits or those canned in water or juice Carbohydrates and Health • • Nutritive sweeteners – Monosaccharides, disaccharides, and sugar alcohols – Natural vs refined Non-nutritive sweeteners – Saccharin – Aspartame – Acesulfame K – Sucralose Carbohydrates and Health • Sugar and dental caries promoted by: – Carbohydrate remaining in the mouth • – Food that sticks to teeth Frequent consumption • Sip high sugar drinks over time ... Carbohydrates? • • Sugars, starches, and fibers Major food sources: Plants – • Produced during photosynthesis Two main carbohydrate types – Simple (Sugars) – Complex (Starches and Simple Sugars • Monosaccharides... juices halt action of salivary amylase and stops carbohydrate digestion Carbohydrate Digestion and Absorption • Digestion – Small intestine • Pancreatic amylase continues starch digestion • Brush... Maltase, sucrase, and lactase split maltose, sucrose, and lactose, respectively Carbohydrate Digestion and Absorption • Digestion – Bonds that link glucose molecules • Alpha bonds – Broken down