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This Document Contains Chapters 3 to 4 CHAPTER 3 THE HUMAN BODY: A NUTRITION PERSPECTIVE OVERVIEW This chapter examines the anatomy and physiology of the human body as it pertains to nutrition. Comprehensive descriptions of the structure and functions of cells and organ systems are described, including the circulatory system, urinary system, nervous system, endocrine system, immune system, and digestive system. A brief section describes the storage capabilities of the body. An introduction to digestion and absorption is presented as part of the discussion of the digestive system. The science of nutritional genomics and its emerging application in personalized nutrition is introduced. The Nutrition and Your Health section reviews common problems with digestion, including heartburn, ulcers, constipation, hemorrhoids, irritable bowel syndrome, diarrhea, gallstones, celiac disease, and gluten insensitivity. KEY TERMS Absorptive cells Absorption Adenosine triphosphate (ATP) Aerobic Anaerobic Anal sphincters Antibody (immunoglobulin) Antigen Anus Amylase Artery Bile Bolus Capillary Cardiovascular system Celiac disease Cell nucleus Chromosome Chyme Connective tissue Constipation Cytoplasm Deoxyribonucleic acid (DNA) Digestion Digestive system Duodenum Endocrine gland Endocrine system Endoplasmic reticulum (ER) Enterohepatic circulation Enzyme Epigenetics Epigenome Epiglottis Epinephrine Epithelial tissue Erythropoietin Esophagus Feces Gallbladder Gastroesophageal reflux disease (GERD) Gastrointestinal (GI) tract Gene Gene expression Golgi complex H2 blockers Hemorrhoids Hepatic portal circulation Hepatic portal vein Histamine Ileocecal sphincter Ileum Insulin Intrinsic factor Jejunum Laxative Lipase Lower esophageal sphincter Lumen Lymph Lymphatic system Lysosome Microvilli Mitochondria Motility Mucus Muscle tissue Myelin Nervous system Nervous tissue Neuron Neurotransmitter Nonceliac gluten sensitivity Nonspecific immunity Norepinephrine NSAIDs Nutrigenetics Nutrigenomics Nutritional genomics Organ Organ system Organelles Peristalsis Peroxisome pH Phagocytosis Pharynx Phospholipid Plasma Prebiotic Probiotic Protease Proton pump inhibitor (PPIs) Pyloric sphincter Receptor Rectum Ribonucleic acid (RNA) Ribosomes Saliva Secretory vesicles Specific immunity Synapse Thyroid hormones Tissues KEY TERMS Cont'd Transcription Translation Ulcer Umami Urea Ureter Urethra Urinary system Vein Villi (singular, villus) White blood cells STUDENT LEARNING OUTCOMES Chapter 3 is designed to allow you to: 3.1 Understand some basic roles of nutrients in human physiology. 3.2 Identify the functions of the common cellular components. 3.3 Define tissue, organ, and organ system. 3.4 Identify the role of the cardiovascular and lymphatic systems in nutrition. 3.5 List basic characteristics of the nervous system and its role in nutrition. 3.6 List basic characteristics of the endocrine system, especially the pancreas, and its role in nutrition. 3.7 List basic characteristics of the immune system and its role in nutrition. 3.8 Outline the overall processes of digestion and absorption in the mouth, stomach, small intestine, and large intestine, as well as the roles played by the liver, gallbladder, and pancreas. 3.9 List basic characteristics of the urinary system and its role in nutrition. 3.10 Understand the importance of the body storage areas for nutrients. 3.11 Understand the emerging field of nutritional genomics. 3.12 Identify the major nutrient-related gastrointestinal health problems and approaches to treatment. LECTURE OUTLINE 3.1 Nutrition’s Role in Human Physiology A. Levels of Organization: cells tissues organs  organ systems 1. Each cell is a self-contained, living entity. 2. Cells of the same type join together to form tissues. 3. One or more tissues combine to form organs. a. Organs are important in nutritional health. b. Overall nutritional state determines how each organ functions. 4. Several organs cooperate and form an organ system. B. Chemical Processes Require: 1. Energy (from macronutrients) 2. Water 3. Building supplies (protein, minerals) 4. Chemical regulators (vitamins) 5. Oxygen is required by most cells as well. 3.2 The Cell: Structure, Function, and Metabolism A. Cell (plasma) Membrane 1. Holds cellular contents together 2. Regulates the flow of substance into and out of the cell 3. Cell-to-cell communication 4. Composed of lipid bilayer (double membrane) of phospholipids, which have both water-soluble and water-insoluble tails (see Fig. 3-1b) 5. Cholesterol—fat-soluble component of membrane; provides stability 6. Proteins—provide structural support, act as transport vehicles, function as enzymes that affect chemical processes, form open channels to allow substances in and out of cell, act as receptors on the membrane surface, act as gates to control flow of various particles into and out of the cell 7. Carbohydrates—act as markers on membrane surface to identify cells, aid in cell-to-cell communication, and immune defense B. Cytoplasm 1. Fluid material and organelles (excluding the nucleus) 2. Site of anaerobic metabolism C. Mitochondria 1. Convert food energy from energy-yielding nutrients into energy that cells can use 2. Site of aerobic metabolism 3. All cells except red blood cells contain mitochondria D. Cell Nucleus 1. All cells except red blood cells contain at least one nucleus 2. Bound by its own double membrane 3. Contains genetic material a. DNA  genes chromosomes b. Gene expression—DNA directs synthesis of proteins 1) DNA’s message (code) is copied to RNA which is then transported to ribosomes which are outside of the nucleus (transcription). DNA never leaves nucleus. 2) On ribosomes, RNA’s message is used to synthesize a protein (translation). c. When cells replicate, all of the DNA is copied, with each cell containing one old strand and one new strand of the double-stranded DNA molecule. E. Endoplasmic reticulum (ER) 1. Continuous network of tubes on the outer membrane of the cell nucleus 2. Rough ER contains ribosomes—sites of protein synthesis 3. Functions of ER a. Protein synthesis b. Some lipid synthesis c. Detoxification of toxic substances d. Calcium storage and release n the cell F. Golgi complex 1. Near the nucleus 2. Packages proteins for use in the cell or for export out of the cell G. Lysosomes 1. Cell’s digestive system to digest worn out or damaged cell components 2. Active in immune function H. Peroxisomes 1. Contain enzymes that detoxify harmful chemicals which results in production of hydrogen peroxide 2. Protective enzyme, catalase, prevents accumulation of hydrogen peroxide in cells 3. Minor role: metabolize alcohol I. Cell Metabolism 1. Chemical processes involved in maintaining life a. Release and use of energy from foods b. Synthesis of compounds c. Preparation of waste products for excretion 2. Anabolic reactions put molecules together and require energy. 3. Catabolic reactions take molecules apart and release energy (e.g., metabolism of energy-yielding nutrients). 4. Metabolism of energy production overview a. Begins in cytoplasm (anaerobic) b. Aerobic energy production takes place in mitochondria c. Convert food energy to adenosine triphosphate (ATP, a high energy compound 3.3 Body Systems A. Types of Tissue 1. Epithelial a. Cover surfaces inside and outside the body b. Functions 1) Secretes substances 2) Absorbs nutrients 3) Excretes wastes 2. Connective a. Supports and protects the body b. Stores fat c. Produces red blood cells 3. Muscle: designed for movement 4. Nervous a. Designed for communication b. Found in brain and spinal cord B. Systems may work together (e.g., digestive system aids immune system by preventing pathogens from entering the body). C. Figure 3-2 outlines the body systems, their major components and functions. 3.4 Cardiovascular System and Lymphatic System A. Cardiovascular System 1. Blood flows through the heart and blood vessels from the pumping of the heart. 2. Blood is made of plasma, red blood cells, white blood cells, platelets, and other substances. 3. Routes of travel a. Blood travels from the right side of the heart to the lungs to pick up oxygen and release carbon dioxide, then travels back to the heart. b. Blood travels from the left side of the heart through the arteries and capillaries to deliver oxygen and nutrients and pick up wastes from the body’s cells, then returns to the heart through veins. 4. Portal circulation in the gastrointestinal tract a. Water and nutrients may be used to nourish cells of the gastrointestinal tract, but most are taken up by capillaries in the small intestine and stomach. b. Capillaries merge into veins that empty into the portal vein. c. Hepatic portal vein leads to the liver d. Liver processes the absorbed nutrients before they enter general circulation. B. Lymphatic System 1. Lymph flows through the lymphatic vessels and lymph tissues. 2. Lymph consists of plasma and white blood cells. 3. Lymph flows throughout body and eventually empties into major veins near the heart. 4. Flow of lymph is driven by muscle contractions from normal body movement. 5. Lymphatic circulation in the gastrointestinal tract a. Lymph vessels pick up the majority of products from fat digestion absorption b. These products are too large to enter the bloodstream directly but are emptied into the bloodstream in a larger vein. 3.5 Urinary System A. Two kidneys remove wastes from the body 1. Help maintain acid/base balance of the blood 2. Convert vitamin D to active hormone 3. Produce hormone erythropoietin, that stimulates red blood cell synthesis 4. Produce glucose from amino acids during fasting 5. Filters excess water-soluble nutrients and minerals B. Urea travels from kidneys to bladder by ureter C. Bladder empties through urethra D. Kidney function depends on cardiovascular function (particularly blood pressure), and fluid status. E. Diabetes, hypertension, and drug abuse are harmful to kidneys. 3.6 Nervous System A. Functions 1. Exercises central control over most body functions 2. Detects (via sensory organs) and responds to changes in the external environment 3. Maintains constant internal environment B. Basic structural and functional unit is the neuron 1. Neurons respond to electrical and chemical signals 2. Conduct electrical impulses 3. Release chemical regulators C. Brain 1. Stores information 2. Reacts to incoming information 3. Solves problems 4. Generates thoughts 5. Plans course of action based on sensory input D. Neurotransmitters carry signals across the synapse (gap) from one neuron to another neuron or target tissue. (See Fig. 3-6). E. Nutrients play a role in nervous system 1. Transmission of nerve signals utilizes potassium and sodium 2. Neurotransmitters are made from nutrients (e.g., amino acids) a. Tryptophan is converted to serotonin b. Tyrosine is converted to norepinephrine and epinephrine 3. Calcium is required for the release of neurotransmitters from the neurons 4. Vitamin B-12 is needed in formation of the myelin sheath that insulates most neurons 5. Glucose is needed to fuel the brain 3.7 Endocrine System A. Major role in regulating metabolism, reproduction, and fluid balance B. Endocrine glands produce hormones and release them into the blood. C. Roles of hormones 1. Permissive (turn on) 2. Antagonistic (turn off) 3. Synergistic (cooperative) D. Some hormones must undergo chemical changes before becoming active (e.g., vitamin D). E. Examples (see Table 3-1) 1. Insulin (see Fig. 3-7) a. Made in and released from pancreas when blood glucose rises b. Helps to control blood glucose by allowing its movement from the blood into muscle and adipose cells c. In liver cells, insulin stimulates conversion of glucose to glycogen for storage 2. Epinephrine, norepinephrine, glucagon, and growth hormone all increase blood glucose. 3. Thyroid hormones a. Made in and released from thyroid gland b. Regulates rate of metabolism F. Each hormone is available only to cells with the correct receptors on their cell membranes. 3.8 Immune System A. Overview 1. Poor nutritional status weakens immune system, increases risk of infection. 2. Two types of immunity a. Non-specific (innate) immunity: protect body from invasion by microorganism 1) Physical and chemical barriers against infection (i.e., skin and intestines) 2) Inflammatory response 3) Phagocytosis by white blood cells b. Specific (adaptive) immunity 1) involves production of immunoglobulins (antibodies) by white blood cells to target specific antigens (foreign proteins) 2) "Memory" created after first attack increases the effectiveness of future attacks. 3. Skin a. Barrier surrounding the body b. Has glands that secrete lysozyme c. Deficiencies of essential fatty acids, vitamin A, niacin, and zinc affect skin’s integrity. 4. Nutrients with important roles in immune system a. Proteins b. Essential fatty acids c. Iron d. Copper e. Zinc f. Vitamin A g. Vitamin C h. Vitamin D i. Vitamin B-6 j. Vitamin B-12 k. Folate 3.9 Digestive System A. Overview 1. Foods must be digested/broken down to provide us with usable nutrients. a. Mechanical digestion 1) Starts with chewing 2) Continues with muscle contractions that move food through the GI tract (motility) b. Chemical digestion—chemicals (enzymes) and acid are secreted into the GI tract to break down food 1) Enzymes specific to one chemical process 2) Enzymes sensitive to acidic and alkaline conditions, temperature, presence of required vitamins or minerals 3) Enzymes secreted by mouth, stomach, pancreas, and small intestine 2. Bacteria in the large intestine produce biotin and vitamin K that can be absorbed and used by the human body. 3. Most digestive processes are under autonomic control. 4. Figure 3-8 outlines the role of the six organs involved in digestive system. 5. Table 3-2 describes important secretions of the digestive tract. 6. Table 3-3 lists the major sites of absorption along the GI tract. B. Mouth 1. Chewing breaks up food, increases surface area 2. Tongue aids chewing and identifies flavors of sweet, salty, bitter, sour, and umami 3. Salivary glands produce saliva a. Salivary amylase digests starch b. Mucus lubricates passage of food, makes swallowing easier C. Esophagus 1. Connects pharynx with stomach 2. Epiglottis prevents swallowed food (bolus) from entering the trachea 3. Peristalsis is a wave of muscle contractions that pushes food down the digestive tract (see Fig. 3-11). 4. Lower esophageal sphincter is a muscle that closes after food enters the stomach to prevent backflow. 5. See Figure 3-10 to understand the process of swallowing. D. Stomach 1. Four-cup holding tank 2. Churns and mixes food (chyme) with gastric juices (water, HCl, and enzymes) 3. HCl secreted by stomach makes stomach acidic a. Acid destroys biological activity of proteins b. Acid converts inactive enzymes to active enzymes c. Partially digests proteins d. Makes dietary minerals soluble for absorption 4. Passage of chyme from the stomach into the small intestine is regulated by the pyloric sphincter (about 1 teaspoon at a time) over course of 1-4 hours 5. Very little nutrient absorption except for alcohol 6. Protection of stomach from autodigestion a. Thick layer of mucus lines stomach b. Acid and enzyme production requires release of gastrin c. Acid production is regulated by hormones 7. Production of intrinsic factor for vitamin B-12 absorption 8. Figure 3-12 illustrates the physiology of the stomach. E. Small intestine 1. About 10 feet long and 1” in diameter 2. Three parts: duodenum, jejunum, ileum 3. Most digestion and absorption occurs in small intestine. 4. Chyme mixes with digestive juices to digest macronutrients and prepare vitamins and minerals for absorption. 5. Villi and microvilli are folds that create large surface area and trap food to promote nutrient absorption (see Fig. 3-13 c and d). 6. Constant turnover of absorptive cells leads to high nutrient needs. 7. Various hormones and other substances participate in the digestive process. 8. Absorption occurs by different processes (see Fig. 3-14). a. Passive absorption b. Facilitated absorption c. Active absorption d. Phagocytosis or pinocytosis 9. Glucose and amino acids are absorbed into the capillaries and enter the portal vein. 10. Most fats are absorbed into the lymph vessels and eventually empty into bloodstream. 11. Undigested food leaves through the ileocecal sphincter. 12. Figure 3-13 illustrates the organization of the small intestine. F. Large intestine 1. Figure 3-15 illustrates the anatomy of the large intestine. 2. Five main segments: cecum, ascending colon, transverse colon, descending colon, sigmoid colon 3. Small amount of unabsorbed carbohydrate, protein, and fat reaches the large intestine. 4. Some vitamins, water, fatty acids, sodium, and potassium are absorbed. 5. No villi or digestive enzymes 6. Large population of bacteria a. Mucus protects large intestine from bacterial infections b. Bacteria play a role in health (bifidobacteria and lactobacilli) c. Break down some remaining food products 7. Probiotics can introduce live bacteria to intestine (found in milk, fermented milk, yogurt, and supplement form). 8. Prebiotics are substances that increase the growth of healthy bacteria. 9. Feces formed G. Rectum 1. Two sphincters control elimination of waste 2. External sphincter is voluntarily controlled H. Accessory organs 1. Liver produces bile 2. Gallbladder stores bile 3. Bile can be recycled through enterohepatic circulation 4. Pancreas provides enzymes and hormones a. Insulin and glucagon regulate blood glucose levels b. Pancreatic juice contains bicarbonate (that neutralizes the acid from the stomach) and digestive enzymes to digest macronutrients 3.10 Nutrient Storage Capabilities A. Adipose cells store fat. B. Muscle and liver store carbohydrates as glycogen. C. Blood contains a small reserve of amino acids and glucose. D. Many vitamins and minerals are stored in the liver. E. Calcium can be taken from the bones if needed. F. Protein can be taken from the muscles if needed. 3.11 Nutrition and Genetics A. Overview 1. Growth, development, and maintenance of cells are directed by genes 2. Epigenetics: changes in gene expression caused by mechanisms other than changes in the underlying DNA sequence 3. Epigenome is the way the genome is marked and packaged inside a cell's nucleus a. Extra layer of instructions beyond the genome code that influences gene activity b. Affected by diet B. The Emerging Field of Nutritional Genomics 1. Nutritional Genomics: study of interaction between nutrition and genetics a. Nutrigenetics: study of the effects of genes on nutritional health b. Nutrigenomics: study of how food impacts health through its interaction with our genes and its subsequent effect on gene expression 2. Areas of research include: a. Obesity b. Cardiovascular disease c. Celiac disease d. Osteoporosis e. Alzheimer's disease C. Nutritional Diseases with a Genetic Link 1. Cardiovascular disease a. 1/500 people have a defective gene that delays removal of cholesterol from the bloodstream. b. Dietary changes can help, but these people need medicine and possibly surgery to address the problem. 2. Obesity a. 60 or more genes are involved in regulation of body weight b. Not every person with a genetic predisposition becomes obese. c. How people live allows each person’s genetic potential to be expressed. 3. Diabetes a. Both types have genetic links b. Type 2 has a strong genetic link that is expressed when one becomes obese. c. More than 200 genes identified as possible causes. 4. Cancer a. Colon, breast, prostate, and other cancers have a genetic link b. Although genetics are an important determinant, lifestyle and environmental factors are significant contributors to risk. D. Your Genetic Profile 1. Examination of family history can help detect genetic disease risks a. 2 or more first-degree relatives with a specific disease b. First-degree relative with a specific disease before age 50–60 c. Identify the controllable risk factors that would contribute to development of a genetically-linked disease in your family. d. Figure 3-17 shows an example of a family tree or genogram. 2. Genetic testing may aid in prevention and/or treatment of genetically-linked diseases. a. Expensive, may take months for results b. Genetic Information Nondiscrimination Act (GINA) prohibits health insurers from raising premiums or denying coverage based on genetic information. E. Personalizing Nutrition Advice 1. Information about genetic profile could help professionals tailor diet to most effectively suit an individual. 2. Emerging field of DNA testing warrants caution Nutrition and Your Health: Common Problems with Digestion A. Heartburn 1. Fifty percent North American adults experience heartburn 2. Movement of acid from the stomach into the esophagus 3. Gastroesophageal reflux disease (GERD) a. Recurrent, more serious problem b. Relaxation of the sphincter that inhibits backflow from the stomach c. Risk factors include pregnancy, obesity d. Symptoms (two or more times per week) 1) Nausea 2) Gagging 3) Cough 4) Hoarseness e. Risks 1) Damage esophagus lining, and possible chronic inflammation 2) Increased risk of esophageal cancer 4. Treatment of heartburn or GERD (see Table 3-4) a. H2 blockers (PPIs) b. Medication to improve motility c. Avoid smoking d. Avoid large doses of NSAIDS e. Achieve or maintain healthy body weight f. Consume small low-fat meals g. Limit alcohol and caffeine consumption h. Consume healthy diet with adequate fiber i. Foods that worsen symptoms include acidic foods, spicy foods, carbonated beverages, chocolate, onions and garlic, peppermint and spearmint j. Avoid tight-fitting clothes k. Elevate head at bedtime l. Avoid eating 3-4 hours prior to bedtime B. Ulcers 1. Acid erodes the mucosal lining of the stomach or tissue lining of the small intestine (see Figure 3-19) 2. Symptoms a. Stomach pain 2 hours after eating b. Weight loss, nausea, vomiting, loss of appetite, bloating c. GI bleeding (warrants medical attention) 3. Principal causes: a. Helicobacter pylori infection b. Medications that impair mucus production by stomach c. Heavy acid production in stomach d. Stress e. Smoking f. NSAIDs 4. Risks a. Erosion completely through the stomach wall, spilling contents into the surrounding body cavities b. Blood loss 5. Treatment a. Antibiotics b. Antacids and Proton Pump Inhibitors (PPIs) c. Minimize coffee, tea, alcohol, pepper, strong spice consumption, chocolate, onions and garlic, peppermint and spearmint d. Minimize the use of NSAIDs e. The calcium in milk and cream stimulates production of stomach acid and inhibits healing C. Constipation 1. Difficult or infrequent evacuation of bowels 2. Causes a. Slow motility of fecal material through large intestine (increased fluid absorption) b. Ignoring normal bowel reflexes c. Antacids and calcium and iron supplements 3. Treatment a. Increasing dietary fiber b. Adequate fluid intake c. Develop regular bowel habits d. Relaxation e. Physical activity f. Short-term use of laxatives may help, but extended use can increase constipation D. Hemorrhoids 1. Swollen veins of the rectum or anus (also called piles) 2. Development can be brought on by a. Pregnancy b. Obesity c. Prolonged sitting d. Strained bowel movements e. Also heredity, diet, and lifestyle 3. Symptoms include pain, itching, and bleeding (although rectal bleeding may have more serious causes, such as cancer) 4. Half of adults over age 50 have develop a hemorrhoid 5. Treatment a. Dietary recommendations are same as for constipation, especially adequate fiber and fluid b. Warm, soft compresses c. Warm water bath d. Topical treatments (i.e., Preparation H) E. Irritable bowel syndrome 1. More common in younger women than younger men; approximately equal incidence in older men and women 2. Symptoms a. Visible abdominal distention b. Pain relief after a bowel movement c. Increased stool frequency d. Loose stools with pain onset e. Mucus in stool f. Feeling of incomplete elimination even after a bowel movement 3. Does not increase the risk for cancer 4. Causes a. Alterations in some of the hormones that regulate intestinal motility b. Inflammatory responses in the GI tract c. Little evidence linking allergies to IBS d. Poorly digested carbohydrates are suspected (i.e., fructose, sugar alcohols) e. Depression and stress 5. Treatment (individualized as causes are variable) a. Increase in soluble fiber but not insoluble b. Avoid dairy products and gas-forming foods 1) i.e., legumes, cabbage, beans, broccoli, grapes, raisins, cherries, and cantaloupe 2) Careful attention should be given to overall dietary adequacy as Vitamin A and Calcium deficiency can be common with the dietary elimination suggested c. Herbal formulations d. Probiotics e. Cognitive behavioral therapy f. Moderate or no caffeine intake g. Low-fat and more frequent, small meals h. Stress reduction i. Psychological counseling j. Antidepressants k. Hypnosis F. Diarrhea 1. Increased fluidity, frequency, or amount of bowel movements 2. Caused usually by infection 3. Also caused by consumption of unabsorbed substances (i.e., sorbitol or other sugar alcohols) and high-fiber diets 4. Treatment a. Drink lots of fluid (can include electrolytes) to prevent dehydration b. Prompt treatment—within 24 to 48 hours for infants and older people G. Gallstones 1. Crystallization of substances in bile, such as cholesterol (see Fig. 3-20) 2. Causes: a. Obesity b. Genetic background c. Advanced age (>60 years) d. Pregnancy e. Reduced gallbladder activity f. Altered bile composition g. Diabetes h. Diet (low fiber) i. Rapid weight loss or prolonged fasting 3. Symptoms: a. Pain in the upper right abdomen b. Gas and bloating c. Nausea and vomiting 4. Treatment usually involves surgical removal of the gallbladder 5. Prevention a. Avoiding overweight and obesity b. Appropriate rate of weight loss (1-2 pounds per week) c. Limiting animal protein sources to focus more on plant protein sources d. High-fiber diet e. Regular physical activity f. Moderate to no caffeine intake g. Moderate to no alcohol intake H. Celiac Disease and Gluten Sensitivity 1. Celiac disease a. Affects 1% U.S. population b. Incomplete digestion of gluten (in wheat, barley, and rye) leaves small peptides which are absorbed into cells of small intestine and elicit inflammatory reaction. 1) Autoimmune response 2) Villi damaged and flattened, thus reducing absorption of nutrients 3) Malabsorption leads to diarrhea, bloating, cramps, gassiness, fatigue, weight loss, anemia, infertility, bone loss c. Diagnosis 1) Blood test detects antibodies to gluten 2) Biopsies 3) Genetic testing d. Treatment includes gluten-free diet 1) Avoid wheat, barley, rye, bran, graham flour, semolina, spelt, malt, possibly oats 2) Rice, potato flour, cornmeal, buckwheat, arrowroot, and soy are gluten free 3) 2004 Food Allergan Labeling and Consumer Protection Act requires identification of wheat on food packages but not barley or rye 4) Gluten can be hidden in sauces, condiments, flavoring agents, processed foods 5) Dining out can be a challenge 2. Nonceliac gluten sensitivity (gluten intolerance) a. Symptoms of celiac disease without the autoimmune response or intestinal pathology (flattened villi) 1) Symptoms: GI symptoms, fatigue, headache, muscle and joint pain, sleep disorders 2) Symptoms subside with gluten-free diet b. Diagnosis: Effectiveness of gluten-free diet BEST PRACTICES: TEACHING STRATEGIES, DEMONSTRATIONS, ACTIVITIES, ASSIGNMENTS, AND MORE 1. Have students trace the digestion of major nutrients (carbohydrates, fats, and proteins) in a meal or a food such as whole milk, pizza, tacos, chocolate pie, or a Quarter Pounder. This should include nutrients involved, site of action, mechanical action, enzymes and bile, hormones, and products. 2. Bring a garden hose to lecture to demonstrate the length (@ 18 feet) of the digestive tract. This visual gives students a tangible example they can more readily comprehend. 3. Use the Rate Your Plate, Are You Taking Care of Your Digestive Tract, activity to make students aware of their digestive tract and to take a closer look at heartburn. 4. Use the Rate Your Place, Create Your Family Tree for Health-Related Concerns, to begin a discussion of nutritional diseases with a genetic link. 5. Have the class discuss implications of having a condition in which one could not release the appropriate gastrointestinal hormones. Ask how the processes of digestion and absorption might be altered. 6. Divide students into groups of three or four individuals. Have each group devise a one-day menu plan for the following digestive complications: ulcers, heartburn, constipation, hemorrhoids, irritable bowel syndrome, and diarrhea. Have each group share their menu with the class; critique for accuracy. CHAPTER 4 CARBOHYDRATES OVERVIEW This chapter discusses the energy-yielding nutrient, carbohydrates. Simple and complex carbohydrates are defined and identified with a highlight on fiber. Carbohydrates found in the food we eat, including nutritive and alternative sweeteners, are explored. The digestion and absorption of carbohydrates are examined. The effects of lactose maldigestion and fiber on health are described. Carbohydrate intake recommendations are summarized, with emphasis on intake of whole grains, fiber, added sugars. The metabolism of carbohydrate is explained highlighting glucose storage, blood glucose regulation, and use of glycemic index to control blood glucose concentration. The Nutrition and Your Health section focuses on Diabetes and metabolic syndrome. KEY TERMS Acceptable Daily Intake (ADI) Acesulfame-K Advantame Amylase Amylopectin Amylose Aspartame Cellulose Congenital lactase deficiency Dental caries Dietary fiber Disaccharide Diverticula Diverticulitis Diverticulosis Epinephrine Fiber Fermentation Fructose Functional fiber Galactose Glucagon Glycemic index (GI) Glycogen Glucose Hemorrhoid Hemicellulose High-fructose corn syrup Hyperglycemia Hypoglycemia Insulin Ketone bodies Ketosis Lactase Lactose Lactose intolerance Lactose maldigestion Lignins Luo han guo Maltase Maltose Metabolic syndrome Monosaccharide Mucilages Neotame Nonfermentable fiber Pectin Phenylketonuria (PKU) Photosynthesis Polysaccharides Saccharin Simple sugar Sorbitol Starch Stevia Sucralose Sucrase Sucrose Sugar Type 1 diabetes Type 2 diabetes Viscous fiber Whole grains Xylitol STUDENT LEARNING OUTCOMES Chapter 4 is designed to allow you to: 4.1 Explain the most important nutritional role of carbohydrates and how they are created. 4.2 Identify the basic structures of the major carbohydrates: monosaccharides, disaccharides, polysaccharides (e.g., starches), and fiber. 4.3 Describe food sources of carbohydrates and list some alternative sweeteners. 4.4 Explain how carbohydrates are taken in and used by the body, including the processes of digestion, absorption, metabolism, and glucose regulation. 4.5 List the functions of carbohydrate in the body, the problems that result from not eating enough carbohydrates, and the beneficial effects of fiber on the body. 4.6 State the RDA for carbohydrate and various guidelines for carbohydrate intake. 4.7 Identify the consequences of diabetes and explain appropriate dietary measures that will reduce the adverse effects of this health problem. LECTURE OUTLINE 4.1 Carbohydrates—Our Most Important Energy Source A. Main fuel source for brain, nervous system and red blood cells B. Energy yield: 4 kcal/g C. Readily available as fuel for all cells in the form of 1. Blood glucose 2. Glycogen a. Stored in muscle b. Stored in liver 1) Helps maintain blood glucose when fasting or when diet does not supply enough glucose 2) Glycogen stores depleted in 18 hours D. Food and Nutrition Board (FNB) recommends consuming 45%-65% of total kilocalories as carbohydrates. E. Choose whole grains, fruits, vegetables, and legumes rather than refined and processed forms of carbohydrates. F. Carbohydrates are formed during photosynthesis. 1. Green plants produce carbohydrates in our foods. 2. 6 carbon dioxide (CO2) + 6 water (H2O) + solar energy  glucose (C6H12O6) + 6 oxygen (O2) 4.2 Forms of Carbohydrates A. Overview 1. Composed of carbon, hydrogen, and oxygen 2. Forms a. Simple (one or two sugars): monosaccharides and disaccharides b. Complex (many sugars): polysaccharides 1) Starches (digestible) 2) Fibers (indigestible) B. Monosaccharides—Glucose, Fructose, and Galactose 1. Basic unit of all carbohydrate structures 2. Glucose a. Major monosaccharide found in the body b. Also known as dextrose c. Glucose in bloodstream is called blood sugar d. Most comes from the breakdown of starches and sucrose e. Almost all carbohydrates are converted to glucose in the liver f. Glucose is source of fuel for cells 3. Fructose a. Also called fruit sugar b. Absorbed in the small intestines and transported to the liver c. Converted to glucose or other compounds (i.e., fat) in liver d. Sources: fruit, sucrose (glucose + fructose), high fructose corn syrup (HFCS) e. When excess fructose is consumed (often as HFCS) it is converted to fat in liver. 4. Galactose a. Large quantities of pure galactose not found in nature b. Usually found as lactose (glucose + galactose) c. Absorbed and transported to liver d. Converted to glucose or glycogen in the liver C. Disaccharides—Sucrose, Lactose, and Maltose 1. Two monosaccharides bonded together, all containing glucose. 2. Sucrose (see Fig. 4-3) a. Glucose + fructose b. Sugarcane, sugar beets, honey, and maple syrup 3. Lactose a. Glucose + galactose b. Milk sugar 4. Maltose a. Glucose + glucose b. Used in beer and liquor industry c. Cereal grains broken down to maltose d. Fermentation: yeast cells convert sugar to alcohol + CO2 D. Complex Carbohydrates 1. Polysaccharides (starch) may contain 1000 or more glucose units bonded together. 2. Found mostly in grains, vegetables, and fruits 3. Food label term "other carbohydrates" refers to starch 4. Plants store carbohydrates in two forms of starch that are digestible by humans. (see Fig. 4-4) a. Amylose: long straight chain of glucose units b. Amylopectin: long branched chain of glucose units 5. Enzymes that break down starches act at the end of the chain a. Amylopectin has more sites for enzymes as it is branched b. Amylopectin is broken down faster and raises blood sugar more quickly 6. Glycogen a. Branched chain for quick energy b. Carbohydrates are stored as glycogen in animal muscles, but meats are not a source of carbohydrate because this glycogen quickly degrades when the animal dies c. Major storage sites: 1) Liver: used to maintain blood glucose 2) Muscle: used to fuel muscle cells, especially during high-intensity or endurance exercise E. Fiber 1. Differ from starches in that the bonds that hold the sugar units together are indigestible by humans so they are not absorbed 2. Forms of non-starch polysaccharides that food labels call "dietary fiber" a. Cellulose b. Hemicellulose c. Pectins d. Gums e. Mucilages f. Lignin 3. Insoluble fiber (nonfermentable) (see Fig. 4-5b) a. Does not dissolve in water b. Not metabolized by intestinal bacteria c. Includes cellulose, hemicelluloses, and lignin d. Structural and woody part of plants like bran and broccoli e. Increase transit time of food through GI tract 4. Soluble fiber (fermentable) (see Fig. 4-5a) a. Dissolve or swell in water b. Fermented by intestinal bacteria c. Includes pectins, gums, and mucilages, as well as some forms of hemicelluloses d. Slows the rate of absorption by attracting water into the GI tract, reduces blood cholesterol, and controls blood glucose 5. Functional fiber a. Fiber (nondigestible) that is added to foods because they show beneficial effects in humans b. Resistant starch, polydextrose, indigestible dextrins, and inulin c. Prebiotics 1) Short-chain carbohydrates (oligosaccharides) that resist human digestion, but provide fuel for beneficial intestinal bacteria 2) Promote human intestinal health 4.3 Carbohydrates in Foods A. Overview 1. Sources in MyPlate: grains, vegetables, fruits, dairy (see Fig. 4-6) 2. Limit foods with added sugars and fats 3. Most carbohydrates come from starch (beans, potatoes, grains, cereals, pasta) 4. Starches provide micronutrients and phytochemicals. 5. See Fig. 4-7 for food sources of carbohydrates listed in descending order by percent RDA and grams of carbohydrate B. Whole Grains 1. Dietary Guidelines recommend consuming at least half of all grains as whole grains, and more specifically 2-3 servings of whole grains per day. 2. A product labeled as "whole grain" must contain a minimum of 51% whole grain ingredients by weight per serving. 3. Benefits (2-3 servings of whole grains per day) come from: a. Increased fiber content when compared to refined grains b. Vitamins and minerals c. Phytochemicals 4. Only 10% people meet recommendation for 2-3 servings whole grains per day a. Most consume less than 1 serving per day b. Preferences in taste, texture, cost, availability, deceptive marketing, help explain inability to meet recommendation 5. Deceptive marketing a. Labeling claim "made with whole grains" does not guarantee the product is whole grain b. Cracked wheat, stoneground wheat, enriched wheat, 12-grain flour, and multigrain are terms that indicate a product may not contain whole grains c. Product must say "100% whole grain" or list "whole" as first word in the ingredient list to be considered whole grain. 6. Whole Grain Stamp can help consumer identify products that are whole grain 7. Healthy, Hunger Free Kids Act of 2010: foods must contain at least 50% whole grains to meet the whole-grain-rich criteria for the federal school meal and child nutrition 8. Table 4-1 lists several whole grains, tips for finding them among products in a store, and health benefits. C. Vegetables 1. Provide carbohydrates as starch and fiber 2. Benefits a. Low in fat and calories, rich in nutrients b. Consumption of recommended amount can reduce risk of chronic disease 3. Vegetables organized in five subgroups: a. Dark green b. Starchy c. Red and orange d. Beans and peas e. Other vegetables f. Recommendations given for weekly intake and dependant on age, sex, physical activity level 4. MyPlate serving size of "1 cup": 1 cup raw or cooked vegetables or vegetable juice, 2 cups raw leafy greens D. Fruits 1. Provide carbohydrates as natural sugar and fiber 2. Health benefits similar to those of vegetables E. Dairy 1. Provide carbohydrates in form of lactose 2. Key nutrients in dairy include: calcium, potassium, vitamin D, protein 3. Foods made from milk that are primarily fat are not part of dairy group (cream, butter, cream cheese) 4. High lactose foods: milk, half and half, plain yogurt, sour cream, heavy cream, cottage cheese, ricotta cheese, ice cream, and ice milk 5. Low lactose foods: aged cheese, processed cheese, milk treated with lactase 6. Recommendations for dairy dependant on age 7. MyPlate serving size of 1 cup of milk: 1 cup milk, yogurt, or soymilk; 1.5 oz natural cheese; 2 oz processed cheese F. Nutritive sweeteners 1. Sugars (mono- and disaccharides) that provide kilocalories and sweetness a. Sucrose is the benchmark against which the sweetness of all other sweeteners is measured b. 4 kilocalories per gram c. 1 tsp = 4.2 grams d. Typical intake is 30 tsp of total sugar/day e. Added sugar 1) Caloric sweeteners added to foods during processing or preparation or before consumption 2) Average intake is 20 tsp per day 3) Recommended intake is 60g/day) can increase risks of intestinal blockage from hard stool, and decrease availability of some nutrients 5. May decrease risk of colon cancer (if from whole foods rather than supplementation); likely due to other nutrients present in high-fiber foods 4.5 Putting Carbohydrates to Work in the Body A. Providing Energy 1. Supply kilocalories to fuel the body a. Red blood cells can only use glucose b. Brain and CNS use glucose but can use ketone bodies c. Muscles and other cells fueled by glucose but can also use fat or protein 2. "Sparing protein" from use as an energy source and preventing ketosis a. Under normal circumstances, digestible carbohydrate is used for energy while protein is reserved for building and maintaining muscles and vital organs b. When not enough carbohydrate is consumed 1) Proteins are converted to glucose and therefore are not available for other functions 2) Long term starvation leads to muscle wasting and possible organ failure 3) Fats are metabolized but the process is incomplete and inefficient, forming ketones, which can disturb acid-base balance. B. Regulating Blood Glucose (see Fig. 4-10) 1. Blood glucose is maintained within a narrow range. a. Pancreas releases insulin when blood glucose rises after a meal 1) Insulin directs liver to store glucose as glycogen 2) Insulin directs muscle, adipose, and other cells to take up glucose from bloodstream 3) Keeps blood sugar from rising too high (hyperglycemia) b. Pancreas releases glucagon when blood glucose falls (i.e., between meals or fasting) 1) Keeps blood sugar from falling too low (hypoglycemia) 2) Prompts liver to break down glycogen to glucose 2. Adrenal gland also plays a role during stress a. Epinephrine (adrenaline) is released in response to stress b. Epinephrine causes quick conversion of glycogen to glucose in the liver for quick response to perceived threat 3. The Glycemic index and Blood Glucose a. Glycemic index is a measure of how a carbohydrate containing food raises glucose. b. Glycemic index (GI) is a ratio of blood glucose response to a given food compared to a reference food or glucose. c. GI is influenced by: 1) Starch structure 2) Fiber content 3) Food processing 4) Physical structure 5) Other macronutrients present in the food or meal d. Useful in diet planning 1) Combine low GI food with high GI food 2) Avoid eating too much high GI foods at one time e. Glucose regulation 1) Low GI carbohydrates typically contain viscous fibers (e.g., oat fiber) and help to slow glucose absorption, leading to better glucose regulation 2) Useful for prevention and management of diabetes f. Table 4-3 provides glycemic index of common foods C. Fiber: Reducing Cholesterol Absorption and Obesity Risk 1. Reducing cholesterol absorption a. Viscous fiber inhibits absorption of cholesterol and bile acids from small intestine, thereby reducing risk of cardiovascular disease and gallstone formation. b. Decreased absorption rate of glucose from increased fiber intake decreases release of insulin and leads to reduced cholesterol synthesis in the liver c. Bacterial production of fatty acids from degradation of soluble fiber in the large intestine may reduce cholesterol synthesis in the liver 2. Reducing obesity risk a. Promotes satiety b. Yields fewer calories 4.6 Carbohydrate Needs A. Overview 1. RDA is 130 g per day for adults a. Based on needs for brain and CNS to prevent ketosis b. Exceeding this amount is fine (keep FNB recommendations in mind) 2. Food and Nutrition Board (FNB) recommends 45-65% of kilocalories as carbohydrate a. Typical American intake of carbohydrate is ~50% of total calories b. Worldwide, carbohydrate intake accounts for ~70% of total calories 3. Carbohydrate intake should be based primarily on fruits, vegetables, whole-grain breads and cereals, and beans rather than on refined grains, potatoes, and sugar. 4. Dietary Guidelines recommend that half of total grain intake is comprised of whole grains. B. How Much Fiber Do We Need? 1. Adequate Intake for Adults is 14 g per 1000 kilocalories a. Females: 25 g/day (21 g/day after age 50) b. Males: 38 g/day (30 g/day after age 50) c. Children (over age 2): fiber intake equals age plus 5 grams per day 2. Average intake is 13 and 17 g/day for women and men, respectively 3. Recommend at least 3 servings of whole grains per day C. How Much Sugar Is Too Much? 1. Diet quality declines when sugar intake is excessive. a. Increased soft drink intake replaces nutrient-dense milk; decreasing intake of vitamin D and calcium, which are important for bone health b. WHO recommends limiting "added sugar" intake to 10% of total energy intake daily, which is about 50 g or 12 tsp of sugar c. Food and Nutrition Board recommends less than 25% of kilocalories from "added sugars" d. Sources of added sugars (see Fig. 4-12): consumption of super-sized soft drinks, cakes, cookies, ice cream, even low-fat and fat-free products supply excess calories e. Table 4-4 lists suggestions for reducing simple sugar intake 2. Sugar and Hyperactivity a. Sugar does no cause hyperactivity b. High carbohydrate meal (low in protein and fat) can actually induce sleepiness 3. Sugar and Oral Health a. Cavities are created when bacteria in mouth metabolize carbohydrate into acid that dissolves tooth enamel b. Worst offenders are sticky, gummy carbohydrate (e.g., caramel) c. Snacking regularly on sweets or sugared chewing gum between meals contributes greatly. d. Fluoridated water and toothpaste decrease dental caries. e. Cheese, peanuts, and sugar-free gum may decrease acid on teeth. Nutrition and Your Health: Diabetes – When Blood Glucose Regulation Fails A. Overview 1. Hyperglycemia (high blood sugar) a. Diabetes affects 11.3% of North Americans b. Thirty seven percent of those with diabetes are unaware of their condition. c. Recent recommendations promote testing fasting glucose every 3 years in all adults over age 45. d. Diagnosis of diabetes: fasting blood glucose ≥ 126 mg/dl or HbA1c >6.5% 2. Hypoglycemia (low blood sugar 7.0% 3. Pathology a. Most cases begin with immune system disorder that destroys the insulin-producing cells of the pancreas b. Pancreas loses ability to synthesize insulin c. Elevated blood glucose leads to glycation of proteins and fats in the body (advanced glycation endproducts), which are toxic to cells 4. Treatment a. Insulin therapy: injections or insulin infusion pump b. Dietary recommendations 1) Three meals and one or more snacks 2) Balance carbohydrate and insulin regimen 3) Carbohydrate amount and timing consistent 4) Ample fiber and polyunsaturated fats 5) Diet low in animal and trans fat 6) Moderate simple carbohydrate intake 7) Balance calorie intake with need 5. Risks associated with type 1 diabetes (particularly poor glucose control over time) a. Cardiovascular disease b. Poor eye and kidney health due to damage to small vessels from high blood sugar c. Excessive ketone production 1) Loss of sodium and potassium in urine 2) Can lead to dehydration, ion imbalance, coma, and death d. Nerve deterioration 1) Mostly in extremities 2) Loss of sensation means not recognizing sores or problems e. Increased risk of infection and amputation f. Decrease risk with adequate glucose control (near HbA1c of 6%) D. Type 2 Diabetes 1. Disease characteristics a. Usually occurs after age 30 b. Most common type, 90-95% of cases c. Incidence rising, especially in children (linked to overweight and obesity) 2. Pathology a. Obesity (especially abdominal obesity) is associated with 80% of cases b. Genetically and environmentally linked c. Insulin receptors on cell surfaces become insulin resistant and glucose is not taken up by the cells efficiently, leading to hyperglycemia d. Insulin production increases, insulin is high at the onset of disease e. Pancreas can't keep up and insulin production is significantly reduced over time 3. To decrease risk, those with family history should avoid obesity, inactivity 4. Treatment a. Achieve healthy weight b. Oral medications or insulin injections (possibly) c. Regular physical activity d. Dietary therapy 1) Regular meals 2) Calorie control 3) Achieve recommended fiber intake (25-30g/day) particularly soluble fiber 4) Reduce intake of added sugars 5) Moderate carbohydrate intake 6) Increase intake of plant oils E. Hypoglycemia 1. Occurs if a person with diabetes takes too much insulin or doesn't eat enough carbohydrate 2. Symptoms a. Shakiness b. Sweating c. Palpitations d. Anxiety e. Hunger f. Confusion g. Fatigue h. Seizures i. Unconsciousness 3. Treat with fast acting glucose source (15 g simple carbohydrate) F. Metabolic syndrome 1. A combination of several or all of the following risk factors: a. Abdominal obesity b. High blood triglycerides c. Low HDL d. Hypertension e. High fasting blood glucose 2. Insulin resistance is the common factor for all the conditions covered by metabolic syndrome 3. A person with metabolic syndrome has increased risk for cardiovascular disease and type 2 diabetes 4. Risk factors for metabolic syndrome a. Age b. Genetics c. Obesity (particularly abdominal obesity) d. Diet e. Activity level 5. Interventions a. Decrease body weight b. Increase physical activity c. Limit total fat consumption d. Increase Omega 3 fat consumption e. Medications to lower blood pressure, total cholesterol, and triglycerides BEST PRACTICES: TEACHING STRATEGIES, DEMONSTRATIONS, ACTIVITIES, ASSIGNMENTS, AND MORE 1. Assign students the Rate Your Plate activity, "Estimate Your Fiber Intake". Discuss the results and use this as an opportunity for the students to consider how they can get more fiber in their diets. 2. Have students go to the supermarket and check breakfast cereal food labels. Ask them to find three cereals with a high dietary fiber content (greater than 10% of the Daily Value). Use this as a springboard to discuss how to boost one's dietary fiber intake. 3. Make hot and cold tea, sweetening one batch with saccharin (Sweet & Low), another with aspartame (Equal), another with sucralose (Splenda), and a last batch with table sugar. Prepare beforehand to determine amounts of each non-nutritive sweetener and sugar needed to achieve approximately equal sweetness. Have students drink and compare the products noting differences in sweetness/taste among cold products, and between cold and hot products (does temperature affect taste?). Have them share their opinions on taste and safety of each sweetener. Instead of purchasing tea and sweeteners, you may wish to purchase products already containing the sweeteners. Just make sure you purchase products with the same flavor so that students are comparing sweetness, not flavor. 4. Invite a person with diabetes, a nurse who works with diabetes, or a dietitian to discuss diabetes mellitus. Also have them address specific aspects of diet and treatment. 5. Bring foods with different sugar contents and place them on a table in front of the class. Have all students try to rank them according to sugar content per serving; place them in order from least sugar to most. Have an index card in front of each item with the approximate number of teaspoons of sugar per serving (5 grams of sugar is approximately 1 teaspoon). Ask a student to come forward to turn over the cards in front of each item to see if they were ranked correctly. Compare food labels or ingredients in the foods and discuss what made one food higher in sugar content than another. 6. Bring a can of regular soda pop, packet of Kool-Aid, jar of iced tea, teaspoon, sugar, a coffee cup, and six glasses to class. Ask students how much sugar they put in coffee, tea, and Kool-Aid. Ask them how much sugar they think is in a can of regular soda pop. Start putting sugar in the coffee cup and have students tell you when they would stop adding sugar to their coffee. Next, start putting sugar in one of the glasses and ask students when they would stop adding sugar to their tea. Do the same for Kool-Aid and soda pop. Now, show the students how much sugar is found in commercial products. Measure out the amount of sugar found in a serving of commercial sweetened ice tea, prepared Kool-Aid, and soda pop (5 grams of sugar is approximately 1 teaspoon). For example, most regular soda pop contains 8 to 10 teaspoons of sugar. Place 10 teaspoons of sugar in a glass and ask them if they would consume that much sugar if you gave it to them. Inform them that is what they are consuming each time they drink a can of regular soda pop. Compare the actual measures of sugar with those the class estimated. Discuss. 7. Have each student in the class bring an empty box of the cereal they eat most often. In groups of six to eight have each student defend his or her choice based on sugar and fiber content per serving. If a cereal is high in sugar and low in fiber, have the student identify alternative cereals he or she could eat that would be more healthful. 8. Purchase milk containing predigested lactose and regular milk. Have students drink and compare the taste of the products. Have students identify dairy alternatives for someone who is lactose intolerant. Instructor Manual for Wardlaw's Contemporary Nutrition Anne M. Smith , Angela L. Collene 9780078021374, 9781260092189

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