The Science of Nutrition

[Virtual Presenter] The Science of Nutrition Fifth Edition Chapter 4 Carbohydrates: Plant Derived Energy Nutrients Slides in this presentation contain hyperlinks. jaws users should be able to get a list of links by using INSERT plus F7 Copyright © 2020 Pearson Education, Inc. All Rights Reserved If this PowerPoint presentation contains mathematical equations, you may need to check that your computer has the following installed: 1) MathType Plugin 2) Math Player (free versions available) 3) N-V-D-A Reader (free versions available).

[Virtual Presenter] What Are Carbohydrates? (1 of 4) One of the three macronutrients Important source of energy for all cells Preferred energy source for nerve cells Composed of carbon, hydrogen, and oxygen Good sources: fruits, vegetables, and grains.

[Audio] What Are Carbohydrates? (2 of 4) Glucose The most abundant carbohydrate Produced by plants through photosynthesis.

[Audio] Figure 4.1. Figure 4.1. Energy from the sun and carbon dioxide from air are absorbed by the plant’s leaves, and water is absorbed through its roots. Glucose is stored in the plant as a starch, and oxygen is released by the plant into the air..

[Audio] What Are Carbohydrates? (3 of 4) Simple carbohydrates Referred to as sugars Contain one or two molecules Commonly referred to as sugars Monosaccharides contain one molecule Glucose, fructose, galactose, and ribose Disaccharides contain two molecules Lactose, maltose, and sucrose.

[Audio] Figure 4.2. Figure 4.2. Glucose is the most abundant sugar molecule in our diet. It is a good energy source. Fructose is the sweetest natural sugar. It is found in fruit and high fructose corn syrup. Galactose does not occur alone in foods. It binds with glucose to form lactose..

[Audio] Figure 4.3. Figure 4.3. Galactose and glucose combine to form lactose, also called milk sugar. Glucose and glucose combine to form maltose. Maltose molecules join in food to form starch molecules. It is a by-product of the fermentation process. Glucose and fructose combine to form sucrose, which is found in sugarcane, sugar beets, and honey..

[Audio] What Are Carbohydrates? (4 of 4) Complex carbohydrates Oligosaccharides contain 3 to 10 monosaccharides Most polysaccharides consist of hundreds to thousands of glucose molecules Starch, glycogen, and most fibers.

[Audio] Figure 4.4. Figure 4.4. Sucrose is produced by an alpha bond between oxygen and 1 carbon from each monosaccharide. Lactose is produced by a beta bond between oxygen and 1 carbon from each monosaccharide..

[Audio] Figure 4.5. Figure 4.5. Starch is the storage form of glucose in plants. It is found in grains, legumes, and tubers. Amylose starch is a straight chain of molecules, while amylopectin starch has a branched structure similar to a tree limb. Glycogen is the storage form of glucose in animals. It is stored in liver and muscles. Glycogen has a branched molecular structure. Fiber forms the support structure of leaves, stems, and plants. It is composed of a series of long chains of polysaccharides..

[Audio] Complex Carbohydrates (1 of 6) Starch Plants store carbohydrates as starch Amylose—straight chain of glucose Amylopectin—branched chain of glucose Resistant starch (fiber)—glucose molecules linked by beta bonds are largely indigestible Sources: grains, legumes, fruits, and vegetables.

[Audio] Complex Carbohydrates (2 of 6) Glycogen Storage form of glucose for animals (humans) Not found in food and therefore not a source of dietary carbohydrate Stored in the liver and muscles.

[Audio] Complex Carbohydrates (3 of 6) Fiber Composed of long polysaccharide chains Dietary fibers are nondigestible parts of plants Functional fibers are nondigestible forms of carbohydrates extracted from plants or manufactured in a laboratory that have known health benefits Total fiber = Dietary fiber plus Functional fiber.

[Audio] Complex Carbohydrates (4 of 6) Soluble fibers Dissolve in water; viscous and gel forming Fermentable, digested by intestinal bacteria Regular consumption can reduce risk for cardiovascular disease and type 2 diabetes Examples: pectin, gum, and mucilage Found in citrus fruits, berries, oats, and beans.

[Audio] Complex Carbohydrates (5 of 6) Insoluble fibers Do not dissolve in water, nonviscous Cannot be fermented by bacteria in the colon Promote regular bowel movements, alleviate constipation, and reduce diverticulosis Examples: lignins, cellulose, and hemicelluloses Good sources: whole grains, seeds, legumes, fruits, and vegetables.

[Audio] Carbohydrate Digestion (1 of 6) Digestion breaks down most carbohydrates into monosaccharides Salivary amylase (amyl starch, -ase an enzyme) Enzyme that begins starch digestion in the mouth Breaks starches down to maltose Carbohydrate digestion does not occur in the stomach Stomach acids inactivate salivary amylase.

[Audio] Carbohydrate Digestion (2 of 6) Majority of carbohydrate digestion occurs in the small intestine Pancreatic amylase Enzyme produced in the pancreas and secreted into the small intestine Digests remaining starch to maltose.

[Audio] Carbohydrate Digestion (3 of 6) Additional enzymes in the microvilli digest disaccharides to monosaccharides Maltase Sucrase Lactase Monosaccharides are absorbed into the mucosal cells lining the small intestine and then enter the bloodstream.

[Audio] Carbohydrate Digestion (4 of 6) Transport Glucose and galactose absorbed via active transport Fructose absorbed via facilitated diffusion (slower absorption).

[Audio] Focus Figure 4.6. Focus Figure 4.6. The table is as follows. A table has 7 rows and 3 columns. The columns have the following headings from left to right. Type of organ, Organ, Description, The row entries are as follows. Row 1. Type of organ, Organs of the g i tract. Organ, Mouth. Description, Chewing stimulates saliva from salivary glands. Salivary amylase breaks down starch into shorter polysaccharides and maltose. Row 2. Type of organ, Organs of the g i tract. Organ, Stomach. Description, Salivary amylase is destroyed by acids. No carbohydrate digestion takes place in the stomach. Row 3. Type of organ, Organs of the g i tract. Organ, Small intestine. Description, Pancreatic amylase breaks down remaining starch into maltose. Specific enzymes, namely maltase, sucrose, and lactase, in the small intestine break down disaccharides into monosaccharides. All monosaccharides are absorbed by the small intestine and enter the bloodstream. Row 4. Type of organ, Organs of the g i tract. Organ, Large intestine. Description, Some carbohydrates pass into the large intestine undigested. Bacteria ferment some undigested carbohydrate. Remaining fiber is excreted in feces. Row 5. Type of organ, Accessory organs. Organ, Salivary glands. Description, Produce salivary amylase. Row 6. Type of organ, Accessory organs. Organ, Pancreas. Description, Produces digestive enzymes and bicarbonate, which are released into the small intestine via the pancreatic duct. Row 7. Type of organ, Accessory organs. Organ, Liver. Description, Monosaccharides travel to the liver in the bloodstream via the portal vein, are converted to glucose, and then are transported to body cells to provide energy. Excess glucose is stored in liver and muscle as glycogen..

[Audio] Carbohydrate Digestion (5 of 6) Fructose and galactose are converted to glucose in the liver Glucose in the bloodstream can provide immediate energy Excess glucose is stored as glycogen in the liver and muscles Liver glycogen used to maintain blood glucose and support brain, spinal cord, and red blood cells Muscle glycogen provides energy to muscles during exercise.

[Audio] Figure 4.7. Figure 4.7. Dietary carbohydrates from the stomach are delivered to the small intestine. Glucose and other monosaccharides are transported to the liver. If needed immediately, it is released into the bloodstream to maintain blood levels of glucose for brain and other body cells. If not needed immediately, glucose is either stored as glycogen in the liver, or transported to muscles and stored as glycogen..

[Audio] Carbohydrate Digestion (6 of 6) We do not have the enzymes necessary to digest fiber Bacteria in the large intestine can ferment some undigested carbohydrates Fermentation produces gases and short chain fatty acids Fiber remaining in the colon adds bulk to stool and is excreted in feces.

[Audio] Blood Glucose Regulation Blood glucose regulated within a narrow range Hormones assist to maintain blood glucose levels: Insulin Glucagon Epinephrine Norepinephrine Cortisol Growth hormone.

[Audio] Blood Glucose Regulation: Insulin Secreted by beta cells of the pancreas Stimulates glucose transporters (carrier proteins) to help move glucose from the blood across the cell membrane Stimulates the liver and muscle cells to take up glucose and store it as glycogen Fructose does not stimulate insulin release Unlike glucose, fructose doesn’t stimulate satiety signals Links with fructose added sugars and obesity.

[Audio] Focus Figure 4.8 (1 of 2). Focus Figure 4.8 (1 of 2).

[Audio] Focus Figure 4.8 (2 of 2). Focus Figure 4.8 (2 of 2).

[Audio] Blood Glucose Regulation: Glucagon Secreted by alpha cells of the pancreas Stimulates the liver to convert glycogen to glucose Assists in the breakdown of body proteins for gluconeogenesis, the production of glucose from amino acids.

[Audio] Blood Glucose Regulation: Epinephrine and Norepinephrine Secreted by the adrenal glands and nerve endings when blood glucose is low Increase glycogen breakdown in the liver, releasing glucose into the blood Increase gluconeogenesis Responsible for our “fight or flight” reactions to danger.

[Audio] Blood Glucose Regulation: Cortisol and Growth Hormone Secreted by the adrenal glands to act on the liver, muscle, and adipose tissue Cortisol increases gluconeogenesis and decreases glucose use by muscles and organs Cortisol implicated in increased risk for weight gain, C 5 D, and diabetes Growth hormone decreases muscle glucose uptake, increases fatty acid mobilization and use, and increases liver glucose output.

[Audio] Blood Glucose Regulation: Glycemic Index (1 of 2) A food’s potential to raise blood glucose Foods with a high glycemic index cause a sudden surge in blood glucose, triggering a large increase in insulin, which may be followed by a dramatic fall in blood glucose Foods with a low glycemic index cause low to moderate fluctuations in blood glucose Foods are assigned a glycemic index value when compared to glycemic effect of pure glucose.

[Audio] Blood Glucose Regulation: Glycemic Index (2 of 2) Not always easy to predict Food’s absorption rate varies with type of carbohydrate, preparation methods, and its fat and fiber content Most foods are eaten in combination in a meal; glycemic index of total meal becomes more important than the ranking of each food.

[Audio] Blood Glucose Regulation: Glycemic Load May be more useful than Glycemic Index Used to determine the effect of a food on a person’s glucose response Grams of carbohydrates in a food are multiplied by the glycemic index Glycemic index and glycemic load remain controversial.

[Audio] Blood Glucose Regulation: Value of Lower Glycemic Load Higher fiber foods help to regulate blood glucose Risk reduction for heart disease and colon cancer Fiber helps to decrease fat levels in the blood (total blood cholesterol and L D L) Foods with lower glycemic index/load: Legumes, fresh vegetables, and whole wheat.

[Audio] The Role of Carbohydrates (1 of 2) Energy Each gram of carbohydrate: 4 kilocalorie Red blood cells use only glucose for energy Brain and nervous tissue rely primarily on glucose Both carbohydrates and fats supply energy for daily activities Glucose is especially important for energy during exercise.

[Audio] Figure 4.10. Figure 4.10. Three circle graphs show carbohydrate use by exercise intensity. Light exercise, 12.5% carbohydrates, 87.5% fat. Moderate exercise, 45% carbohydrates, 55% fat. Intense exercise, 67% carbohydrates, 33% fat..

[Audio] The Role of Carbohydrates (2 of 2) Ketosis Occurs when carbohydrate intake is too low to supply glucose to the brain Breakdown of stored fat during fasting, low carbohydrate intake, or vigorous exercise forms ketones Excess ketones increase blood acidity and cause ketoacidosis Sufficient energy from carbohydrates prevents ketone production.

[Audio] Carbohydrates Spare Protein Gluconeogenesis occurs when the diet doesn’t provide enough carbohydrates The body will make its own glucose from the breakdown of body proteins Amino acids from these proteins cannot be used to make new cells, repair tissue damage, support the immune system, or perform any other function Using amino acids in this way can cause serious damage to organs (heart, liver, and kidneys).

[Audio] Complex Carbohydrates Have Health Benefits Fiber May prevent chronic and digestive diseases Promotes bowel health and reduces the risk of diverticulosis and intestinal problems May reduce the risk of colon cancer May reduce the risk of heart disease May lower the risk of type 2 diabetes May enhance weight loss.

[Audio] Figure 4.11. Figure 4.11. Several bulging pockets, called diverticula, have formed in the wall of a colon. Some feces is trapped inside one of these diverticula, which is inflamed..

[Audio] Figure 4.12. Figure 4.12. The list is as follows. 1. Liver synthesizes bile using cholesterol 2. Bile is stored in gallbladder. 3. Bile is secreted into intestine to aid in the digestion of fat. In a high fiber diet, the following occurs next. 4 a. Fiber binds to bile and both are excreted in the feces. 5 a. Less cholesterol is reabsorbed from the remaining bile. 6 a. Blood levels of cholesterol are reduced. In a low fiber diet, the following happens instead. 4 b. Less fiber is present to bind to bile, so less bile is excreted in the feces. 5 b. More cholesterol is reabsorbed from the remaining bile. 6 b. Blood levels of cholesterol are elevated..

[Audio] How Much Carbohydrate? Recommended Dietary Allowance (R D A) is 130 grams/day Based on the amount of glucose the brain uses Not enough to support daily activities Acceptable Macronutrient Distribution Range (A M D R) is 45% to 65% of daily calories Focus on fiber rich carbohydrate foods.

[Audio] Table 4.1 Dietary Recommendations for Carbohydrates Institute of Medicine (H M D) Recommendations* 2015–2020 Dietary Guidelines for Americans† Recommended Dietary Allowance (R D A) for adults 19 years of age and older is 130 grams of carbohydrate per day. The Acceptable Macronutrient Distribution Range (A M D R) for carbohydrate is 45%–65% of total daily energy intake. Consume a healthful eating pattern that accounts for all foods and beverages within an appropriate Calorie level. A healthful eating pattern includes: a variety of vegetables from all subgroups (dark green, red and orange, legumes, starch and other); fruits (especially whole fruits); grains (at least half of which are whole grains); fat free or low fat dairy; a variety of protein foods; and oils. Added sugar intake should be 25% or less of total energy intake each day. Consume less than 10% of Calories per day from added sugars. Sources: Data from *Institute of Medicine, Food and Nutrition Board, 2005. Dietary Reference Intakes for Energy, Carbohydrates, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients). Washington, D C: The National Academy of Sciences. Reprinted with permission. Data from †U S Department of Health and Human Services and U S Department of Agriculture. 2015–2020 Dietary Guidelines for Americans (8th ed.)..

[Audio] Simple Carbohydrates Diets high in simple sugars: Most Americans eat too much added sugar Contribute to tooth decay Increase risk factors for C 5 D Associated with diabetes and obesity.

[Audio] Figure 4.13. Figure 4.13. A layer of dentin surrounds the pulp cavity, which contains blood vessels leading to nerves. The portion of the dentin exposed inside the mouth is surrounded by a layer of enamel. A cavity has worn through the enamel layer and into the dentin layer..

[Audio] Complex Carbohydrates (6 of 6) Most Americans don’t meet the Adequate Intake (A I) for fiber: 25 gram per day for women 38 gram per day for men, or 14 gram fiber per 1000 kilocalorie consumed per day Whole grain foods are high in fiber, micronutrients, and phytochemicals Whole grains have a lower glycemic index.

[Audio] Table 4.2 Terms Used to Describe Grains and Cereals on Nutrition Labels Term Definition Brown bread Brown bread may or may not be made using whole grain flour. Many brown breads are made with white flour with brown (caramel) coloring added. Enriched (or fortified) Enriching or fortifying involves adding nutrients to refined foods. In order to use this term in grain products in the United States, a minimum amount of iron, folate, niacin, thiamin, and riboflavin must be added. Other nutrients can also be added. Refined Refining involves removing the coarse parts of food products; refined wheat flour is flour in which all but the internal part of the kernel has been removed. Stone ground This term refers to a milling process in which limestone is used to grind any grain. Stone ground does not mean hat bread is made with whole grain because refined flour can be stone ground. Unbleached flour Unbleached flour has been refined but not bleached; it is very similar to refined white flour in texture and nutritional value. Wheat flour This term means any flour made from wheat; it includes white flour, unbleached flour, and whole wheat flour. White flour White flour has been bleached and refined. All purpose flour, cake flour, and enriched baking flour are all types of white flour. Whole grain flour This is flour made from grain that is not refined; whole grains are milled in their complete form with only the husk removed. Whole wheat flour Whole wheat flour is an unrefined, whole grain flour made from whole wheat kernels..

[Audio] Figure 4.14. Figure 4.14. A whole grain includes the germ and endosperm, which are together surrounded by the bran..

[Audio] Figure 4.15. Figure 4.15. The list is as follows. Legumes • Navy beans, cooked, 1 half cup, 9.5 grams • Lentils, cooked, 1 half cup, 8 grams • Black beans, cooked, 1 half cup, 7.75 grams • Kidney beans, cooked, 1 half cup, 6.25 grams Fruits • Blackberries, 1 cup, 7.75 grams • Pear, 1 medium with skin, 5.5 grams • Banana, 1 medium, 3.25 grams • Strawberries, fresh, whole, 1 cup, 3 grams Vegetables • Broccoli, cooked, 1 cup, 5 grams • Corn, canned, 1 cup, 3.5 grams • Asparagus, cooked, 6 spears, 1.8 grams • Lettuce, iceberg, 1 cup, 0.75 grams Breads • Oatmeal, instant, 1 packet, 4 grams • Whole wheat bread, 1 slice, 1.85 grams • Pumpernickel bread, 1 slice, 1.75 grams • White bread, 1 slice, 0.5 grams Values are approximate..

[Audio] Meal Focus Maximizing Fiber Intake. Meal Focus Maximizing Fiber Intake.