CH-7-8 Energy Balance and Weight Control – Wardlaw’s Contemporary Nutrition : Chapter Notes

This Document Contains Chapters 7 to 8 CHAPTER 7 ENERGY BALANCE AND WEIGHT CONTROL OVERVIEW This chapter first addresses energy balance, including energy intake and expenditure. Factors that contribute to energy expenditure and ways to determine it are described. Energy imbalances and determining a healthy body weight are discussed with considerable time devoted to diagnosing obesity. An emphasis is placed on the fact that obesity has multiple causes, with both heredity and environment playing roles. Arguments for and against the Set Point Theory are presented. The discussion of obesity treatment emphasizes controlling energy intake, increasing energy expenditure, and modifying behavior. Principles for a sound weight-loss plan are discussed. Suggestions for obtaining professional help and managing morbid obesity, including medications and surgery, are provided. Treatment of underweight is discussed. The Nutrition and Your Health section, investigates current popular diets and their safety and efficacy. KEY TERMS Adaptive thermogenesis Adjustable gastric banding Air displacement Amphetamine Bariatrics Basal metabolism Bioelectrical impedance Body mass index (BMI) Bomb calorimeter Brown adipose tissue Chain-breaking Cognitive restructuring Contingency management Direct calorimetry Dual Energy X-ray Absorptiometry (DEXA) Energy balance Gastroplasty Hypothalamus Identical twins Kilocalorie Indirect calorimetry Lean body mass Leptin Lower-body obesity Negative energy balance Positive energy balance Relapse prevention Resting metabolism Self-monitoring Set point Sleeve gastrectomy Stimulus control Thermic effect of food Thrifty metabolism Underwater weighing Underweight Upper-body obesity Very-low-calorie diet (VLCD) STUDENT LEARNING OUTCOMES Chapter 7 is designed to allow you to: 7.1 Describe energy balance and the uses of energy by the body. 7.2 Compare methods to determine energy use by the body. 7.3 Discuss methods for assessing body composition and determining whether body weight and composition are healthy. 7.4 Explain factors associated with the development of obesity, and outline the risks to health posed by overweight and obesity. 7.5 List and discuss characteristics of a sound weight-loss program. 7.6 Describe why reduced calorie intake is the main key to weight loss and maintenance. 7.7 Discuss why physical activity is a key to weight loss and especially important for later weight maintenance. 7.8 Describe why and how behavior modification fits into a weight-loss program. 7.9 Outline the benefits and hazards of various weight-loss methods for severe obesity. 7.10 Discuss the causes and treatment of being underweight. 7.11 Evaluate popular weight-reduction diets and determine which are safe and successful. LECTURE OUTLINE 7.1 Energy Balance A. Overview 1. Maintaining a healthy weight is associated with longevity and high quality of life 2. 68.8% of North American adults are overweight 3. 34% of North American adults are obese 4. Figure 7-1 illustrates obesity trends among U.S. adults. 5. Prevention is key: 10 pound weight gain or increase of 2 inches WC should signal reevaluation of diet and lifestyle 6. Successful weight loss comes from hard work and commitment 7. Calorie restriction, increased physical activity, and behavior modification are three elements of a successful weight loss program B. Positive and Negative Energy Balance 1. Figure 7-2 displays a model for energy balance 2. Equilibrium between intake and output results in weight maintenance 3. Positive energy balance is required during pregnancy, infancy, and childhood 4. Negative energy balance is required for successful weight loss; results in reduction of some lean tissue in addition to adipose tissue. 5. Weight gain is a result of excess food intake coupled with limited physical activity and slower metabolism C. Energy Intake 1. “Defensive eating” a. Making careful and conscious food choices, especially regarding portion size b. Required to limit calorie intake in an environment with an abundant food supply and many modern conveniences that decrease physical activity 2. Bomb calorimeter: instrument used to determine calorie content of food 3. Energy content of macronutrients and alcohol (adjusted for digestibility and absorbability) a. Carbohydrates yield 4 calories/gram b. Protein yields 4 calories/gram c. Fat yields 9 calories/gram d. Alcohol yields 7 calories/gram D. Energy Output 1. Basal metabolism a. Minimum energy expended in a fasting state b. 60% to 75% of total energy use by body c. Resting metabolic rate (RMR) is higher than BMR and is the amount of calories a body uses when not in strict fasting state as with BMR d. Factors that influence basal metabolism 1) Lean body mass 2) Amount of body surface 3) Gender 4) Body temperature 5) Thyroid hormone 6) Stress 7) Pregnancy 8) Caffeine and tobacco use e. Basal metabolism lowered 10% to 20% during low-kilocalorie intake (150 to 300 kcals per day) f. Basal metabolic rate declines about 1-2% each decade past age 30 2. Energy for physical activity a. 15% to 35% of total energy output b. Emphasis on increasing general activity c. Obesity linked to inactivity 3. Thermic effect of food (TEF) a. 5% to 10% of total calories eaten b. "sales tax" for food eaten c. TEF value for protein-rich meal is higher than TEF for carbohydrate-rich meal which is still greater than fat-rich meal. d. Larger meals result in higher TEF values than same amount of food eaten slowly over many hours. 4. Adaptive Thermogenesis a. Increase in non-voluntary physical activity (e.g., shivering, fidgeting) b. Accounts for very small portion of energy use c. Brown adipose tissue: specialized adipose tissue that wastes calories as heat 1) Infants and hibernating animals have brown adipose tissue; adults have very little 2) Probably used for temperature regulation 7.2 Determination of Energy Use by the Body A. Direct and Indirect Calorimetry 1. Direct calorimetry measures release of body heat a. Person resides in insulated chamber b. Calculates energy expenditure by measuring change in temperature of water surrounding the insulated chamber c. Expensive and complex 2. Indirect calorimetry measures amount of oxygen consumed and carbon dioxide expelled (see Fig. 7-6) a. Predictable relationship between body’s use of energy and oxygen b. More convenient and portable than direct calorimetry B. Estimates of Energy Needs 1. Estimated Energy Requirements (EER): Food Nutrition Board a. For men 19 years and older: 1) EER = 662 – (9.53 × AGE) + PA × (15.91 × WT + 539.6 × HT) b. For women 19 years and older: 1) EER = 354 – (6.91 × AGE) + PA × (9.36 × WT + 726 × HT) c. Variables 1) EER = estimated energy requirement 2) AGE = age (years) 3) PA = physical activity estimate 4) WT = weight (kg) 5) HT = height (m) 2. To estimate your caloric needs, you can go to www.ChooseMyPlate.gov 3. Figure 7-7 presents MyPlate caloric guidelines for different ages and genders 7.3 Assessing Healthy Body Weight A. Overview 1. Factors to consider when determining a healthy weight a. Weight history should be considered b. Pattern of fat distribution in the body c. Family history of weight-related disease d. Current health status 1) Hypertension 2) Elevated LDL-cholesterol 3) Family history of obesity, cardiovascular disease, or certain forms of cancer (e.g., uterus, colon) 4) Pattern of upper-body fat distribution 5) Elevated blood glucose 2. Healthy lifestyle contributes more to health status than number on the scale a. Eat according to hunger cues and remain physically active b. Allow nature to take its course c. Healthy weight is individualized; considered in terms of health, not math B. Body Mass Index (BMI) 1. BMI is a convenient clinical tool to estimate weight status 2. Diagnosis of obesity depends on BMI, assessment of body fat amount and distribution, and weight-related medical problems 3. Weight (in kg) divided by height2 (in meters) (see Table 7-1) a. BMI 40 or greater: severely obese b. BMI 30–39.9: obese c. BMI > 25: health risks begin d. BMI of 18.5 to 24.9 is healthy 4. BMI should not be applied to a. Children or adolescents still growing b. Frail older people c. Pregnant and lactating women d. Highly muscular individuals 5. Figure 7-8 illustrates estimates of body shapes at different BMI values. 6. Figure 7-9 displays a convenient height/weight table based on BMI. 7. Easier to measure than total body fat C. Estimating Body Fat Content and Diagnosing Obesity 1. Table 7-2 presents health problems associated with excess body fat. 2. Desirable amount of body fat a. Women: 16% to 30% (>35% considered obese) b. Men: 11% to 20% (>24% considered obese) 3. Body fat estimation methods a. Underwater weighing: determines body volume by measuring difference in convention body weight and underwater body weight (see Fig. 7-10). b. Air displacement (BodPod): body volume quantified by measuring the space a person takes up inside a measurement chamber (see Fig. 7-11). c. Skinfold thickness: use calipers to measure the fat layer directly under the skin at multiple sites and then plug these values into a formula (see Fig. 7-12) d. Bioelectrical impedance: measures resistance to an electrical current to determine fat and lean mass (see Fig. 7-13) e. Dual Energy X-ray Absorptiometry (DEXA): uses X-rays to determine weight of fat, fat-free soft tissue, and bone mineral; is considered most accurate method of body fat assessment (see Fig. 7-14) D. Using Body Fat Distribution to Further Evaluate Obesity 1. Upper body (android) obesity (see Fig. 7-15) a. Related to insulin resistance and fatty liver leading to heart disease, high blood lipids, and diabetes b. Encouraged by alcohol intake, smoking, and testosterone c. Apple shape d. Waist circumference > 40" (102 cm) for men; > 35" (88 cm) for women e. Along with BMI > 25, associated with significant health risk 2. Lower body (gynoid) obesity (see Fig. 7-15) a. Fat resists being shed b. Encouraged by estrogen and progesterone c. Pear shape 7.4 Why Some People Are Obese—Nature versus Nurture A. How Does Nature Contribute to Obesity? 1. Genetic background accounts for up to 70% of weight differences between people 2. Inherited "thrifty metabolism" predisposes one to obesity; enables us to store fat readily 3. Chances of becoming obese a. 10% if no obese parents b. 40% if one obese parent c. 80% if two obese parent 4. Genes determine metabolic rate, fuel use, brain chemistry 5. Does the body have a set point for weight? a. Set-point theory: genetically predetermined weight or fat content b. Supporting evidence 1) Hypothalamus monitors the amount of body fat in humans and tries to keep it constant 2) Leptin: hormone released from adipose, promotes sense of fullness and reduction of appetite 3) Thyroid hormone levels decrease when calorie intake is low, reducing metabolic rate 4) With weight loss, body becomes more efficient at storing fat by increasing lipoprotein lipase activity. c. Opposing views 1) Weight does not remain constant throughout life 2) Weight changes with changes in environment 3) Resistance to weight gain is much less than resistance to weight loss B. Does Nurture Have a Role? 1. Environmental factors can impact weight 2. High-fat diets and inactivity promote weight gain 3. Poverty can contribute to obesity 4. Inactivity, stress, boredom, and large pregnancy weight gain are associated with obesity 5. Adult obesity is often rooted in childhood obesity for women 6. Culture influence perceptions of beauty and body weight 7.5 Treatment of Overweight and Obesity A. Losing Body Fat 1. No longer use "3500-kcal rule" as predictor of weight loss (reduction of 500 kcal per day will lead to loss of 1 pound per week) 2. For overweight: Deficit of 10 kcal/day results in 1 pound weight loss over 3 years 3. Deficit of 500 kcal/day results in 25 pound weight loss in one year, with continued loss of 22 pounds by the end of 3 years. 4. Weight loss occurs over time (not linear) 5. See web-based body weight simulator (http://bwsimulator.niddk.nih.gov) B. What to Look for in a Sound Weight-Loss Plan 1. Control calorie intake; slow steady loss 2. Increase physical activity 3. Behavior Modification 4. Figure 7-16 lists characteristics of a sound weight-loss plan in 5 categories a. Rate of loss b. Flexibility c. Adequate intake of nutrients d. Behavior modification e. Overall health 5. Recommendations included in the 2010 Dietary Guidelines for Americans include decreasing caloric intake, while maintaining adequate nutrition, to result in a slow and steady weight loss C. Weight Loss in Perspective 1. Importance of obesity prevention 2. Need for public health strategies 3. Focus on children and adolescents 4. Shift adult focus to weight maintenance and increased physical activity 7.6 Control of Calorie Intake—The Main Key to Weight Loss and Weight Maintenance A. Overview 1. Kilocalorie control: lose 1 pound per week a. 1200 kilocalories per day for women b. 1500 kilocalories per day for men 2. Lower fat, high fiber intake most successful in long term studies 3. Portion control and lower energy dense foods 4. Monitoring kilocalorie intake a. Read labels (see Fig. 7-18) b. Keep food records c. Measure portions d. Low/no calorie beverages e. Use ChooseMyPlate.gov online to track your caloric intake and compare those calories to those expended during physical activity. 5. Table 7-4 shows how to start reducing calorie intake. B. Controlling Hunger 1. Understand how to distinguish true hunger from emotional eating 2. Grehlin is a hormone that, along with empty stomach signals brain when you are hungry; signal can be delayed and take 20 minutes to reach brain 3. Goal: avoid being so hungry that you binge 4. Drinking water and high-volume foods can decrease hunger 5. Mindful eating can be a good approach C. Conquering the Weight-Loss Plateau 1. Healthy weight loss is slow, erratic, and can lead to plateaus 2. Weight loss begins quickly as water and fat are both reduced. 3. "Calorie creep" contributes to plateau; calorie reduction is hard to maintain 4. Decreased metabolism from reduction in calorie contributes to plateau 7.7 Regular Physical Activity—A Second Key to Weight Loss and Especially Important for Later Weight Maintenance A. Benefits of physical activity are manifold 1. Enhanced calorie burning during and after exercise 2. Boosts self-esteem 3. Expending only 100-300 extra kcal/day above normal activity while controlling calories can lead to steady weight loss B. 2008 Physical Activity Guidelines for Americans 1. 150 minutes/week of moderate-intensity aerobic activity to maintain body weight 2. Some individuals may require more than 300 minutes/week to observe benefits C. Duration and regular performance are the keys to success 1. Choose an activity that can be continued over time 2. Lighter intensity activities are less likely to result in injury D. Resistance exercise to increase lean body mass E. Increase routine activity by parking farther away, using stairs, etc. F. Use pedometer to track activity; aim for 10,000 steps. 7.8 Behavior Modification—A Third Strategy for Weight Loss and Management A. Goals for weight loss should be realistic, focusing on behavior change. B. Table 7-6 lists behavior modification principles for weight loss C. The 2010 Dietary Guidelines for Americans has identified behaviors that are related to body weight. 1. Focus on the total number of calories consumed. 2. Monitor food intake. 3. When eating out, choose smaller or lower-calorie portions. 4. Prepare, serve, and consume smaller portions of foods and beverages, especially those high in calories. 5. Eat a nutrient-dense breakfast. 6. Limit your screen time. D. Mindful Eating 1. Make changes to avoid triggers that may tempt you to eat less healthy food or to eat too much, or both. 2. Being aware of the entire eating experience from food preparation to consumption, recognizing and respecting hunger and satiety cues E. Other Behavior Modification Strategies 1. Chain-breaking: separates behaviors that occur together (e.g., eating chips and watching television) 2. Stimulus control: removes temptations (e.g., remove fat-laden snacks from view) 3. Cognitive restructuring: changes frame of mind (e.g., exercise rather than binge for stress reduction) 4. Contingency management: prepares for situations that may trigger overeating or hinder physical activity 5. Self-monitoring: reveals patterns that explain problem eating habits; key behavioral tool for weight-loss program F. Relapse Prevention Is Important 1. Can be considered hardest part of weight control 2. Changing self defeating thoughts 3. Acknowledge relapse but move forward G. Social Support Aids Behavioral Change 1. Friends and family can both help and harm efforts 2. Continued relationship with health professional for accountability can be important H. Societal Efforts to Reduce Obesity 1. The 2010 Dietary Guidelines for Americans contains three guiding principles a. Ensure all Americans have access to nutritious foods and opportunities for physical activity b. Help individuals change behaviors through environmental strategies c. Help individuals with lifelong healthy eating, physical activity, and weight-management behaviors 2. Changes in foods eaten outside the home 3. Social marketing programs to promote healthy eating and active living 7.9 Professional Help for Weight Loss A. Overview 1. Healthcare professionals a. Physician b. Registered dietitian c. Exercise physiologist 2. Weight loss organizations may help, but are also expensive and may not utilize the expertise of licensed healthcare professionals a. Take Off Pounds Sensibly (TOPS) b. Weight Watchers c. Jenny Craig d. Physicians’ Weight Loss Center B. Medications for Weight Loss 1. Who are candidates? BMI > 30 or > 27 with weight-related conditions 2. Medications alone have not been found to be successful 3. Classes of Medications a. Phenteramine (Fastin or Ionamin) prolongs the activity of epinephrine and norepinephrine in the brain (appetite reduction) b. Orlistat (Xenical) reduces fat digestion by inhibiting lipase activity in the small intestine (see Fig. 7-19) 1) Fat intake must be controlled to avoid unpleasant side effects of fat malabsorption 2) Absorption of fat-soluble vitamins is limited c. Lorcaserin hydrochloride (Belviq) alters serotonin receptors found within the feeding center of the hypothalamus of the brain d. Off-label applications: some medications are not approved for weight loss per se, but weight loss is a side effect (e.g., some antidepressants) e. Medications may aid weight loss, but are not a substitute for calorie control, increased physical activity, and behavior modification C. Treatment of Severe Obesity 1. Very-low-calorie diets a. Used in patients with body weight >30% above healthy weight b. Require careful monitoring of a physician c. Health risks 1) Heart problems 2) Gallstones d. 400–800 kilocalories/day; low in carbohydrate and fat, high in high-quality protein e. Weight regain is likely without maintenance plan and long-term support 2. Bariatric surgery (see Figure 7-20) a. Types of surgery 1) Adjustable gastric banding reduces the opening from the esophagus to the stomach with a hollow gastric band that can be adjusted using a port placed beneath the skin 2) Gastric bypass (gastroplasty or stomach stapling) reduces the stomach capacity, leading to rapid satiety b. Patient selection criteria 1) BMI > 40 2) BMI > 35 accompanied by serious obesity-related health concerns 3) History of obesity (at least five years) with previous attempts at weight loss 4) No history of alcoholism or untreated psychiatric disorders c. Health risks 1) Bleeding 2) Blood clots 3) Hernias 4) Severe infections 5) Nutrient deficiencies (e.g., iron, calcium) 6) Death (as high as 2%) d. Other concerns 1) Surgery costs $17,000–$35,000 2) May not be covered by insurance 3) Follow-up surgery may be required to correct stretched skin 4) Major lifestyle change e. Results 1) 75% of patients lose and keep off 50% or more of excess body weight 2) Reductions in blood sugar, cholesterol, and blood pressure common. 3. Lipectomy a. Surgical removal of fat via suction b. Risks include infection, lasting depressions in skin, blood clots, kidney failure, and possibly death. c. Expensive 7.10 Treatment of Underweight A. Overview 1. BMI 70) and those with limited sun exposure 3. All infants, children, and adolescents need minimum of 400 IU daily 4. Vitamin D supplementation is endorsed for all infants (breastfed or formula fed) 5. Use of fortified foods and supplements is a good practice for those with limited sunlight exposure 6. Increased intakes likely for vegans or those with milk allergies or lactose intolerance. F. Avoiding Too Much Vitamin D 1. Supplementation with high doses can result in over-absorption of calcium and calcium deposits in kidneys and other organs a. Weakness b. Loss of appetite c. Diarrhea and vomiting d. Confusion e. Increased urine output 2. Does not result from excessive sun exposure 8.4 Vitamin E A. Functions of Vitamin E 1. Antioxidant a. Resides in cell membranes, where it prevents oxidation of fats in the membrane b. Important in cells exposed to high levels of oxygen: red blood cells and lungs c. Increased intake thought to attenuate atherosclerosis and cataract development. d. Greater evidence exists to support lifestyle changes (consuming fruits, vegetables, and whole grains, performing regular physical activity, avoiding smoking, and maintaining healthy body weight) for cardiovascular disease and cancer risk reduction compared to vitamin E supplements 2. Other roles a. Formation of muscles and central nervous system in early development b. Improves vitamin A absorption if it is low c. Role in metabolism of iron d. Maintenance of nerve tissue and immune function B. Vitamin E Deficiency 1. Vulnerable populations a. Preterm infants: low vitamin E stores, because it is transferred late in pregnancy i. Oxidative damage could lead to hemolysis of RBCs ii. Time of rapid growth with high oxygen needs increases oxidative stress on cells b. Smokers as smoking destroys vitamin E in lungs c. Individuals on very low-fat diets (<15%) or who suffer from fat malabsorption 2. Consequences a. Cell membrane breakdown b. Oxidation of unsaturated fats c. Hemolysis of RBCs C. Getting Enough Vitamin E 1. Only synthesized by plants 2. Few grains have vitamin E as removing germ removes the vitamin 3. Food sources (Figure 8-13 presents sources of vitamin E from MyPlate) a. 2/3 Vitamin E from salad oils, margarines, spreads, and shortening b. Fortified breakfast cereals c. Wheat germ 4. Animal fat has almost no vitamin E 5. Intake Recommendations a. RDA: 15 mg/d of alpha-tocopherol b. 22 IU of natural source (d isomer; I IU = 0.67 mg) c. 33 IU of synthetic source (dl isomer; 1 IU = 0.45 mg)] d. Average intake: 2/3 RDA from food sources D. Avoiding Too Much Vitamin E 1. Stored in adipose tissue and not liver 2. UL: 1000 mg of supplemental alpha-tocopherol (1500 IU from natural sources or 1100 IU from synthetic) 3. Can antagonize vitamin K’s role in blood clotting, leading to hemorrhage 4. Caution with anticoagulant medications 5. Supplements can produce nausea, GI distress, and diarrhea. 8.5 Vitamin K A. Functions of Vitamin K 1. Cofactor in chemical reactions enabling proteins to bind calcium—basis for its role in blood clotting (see Fig. 8-14)—leads to conversion of fibrinogen to fibrin (i.e., the clot) 2. Bone health B. Vitamin K Deficiency 1. Newborns given injection shortly after birth as their gut is sterile and cannot produce enough vitamin K. 2. Deficiency can occur with long term use of antibiotics which destroy vitamin K producing bacteria 3. Deficiency can develop if intake is poor as it is not stored in great amounts. C. Getting Enough Vitamin K 1. Major food sources include green leafy vegetables, broccoli, asparagus, and peas (see Fig. 8-15) 2. Intestinal bacteria produce vitamin K 3. Resistant to cooking losses 4. Not stored in excess; can be excreted by urine c. Average intake meets RDA 5. Toxicity rare 8.6 The Water-Soluble Vitamins and Choline A. Overview 1. Regular consumption important 2. Readily excreted in urine and stool 3. Very little stored 4. Easily lost in cooking, processing, and preparation 5. Light cooking, steaming, and stir-fry best to preserve (review Table 8-1) 6. The B vitamins a. Function as coenzymes (see Fig. 8-16) in metabolism of carbohydrates, protein, and fat (see Fig. 8-17) b. Found in similar foods, so deficiencies usually occur together c. Deficiencies seen first in GI tract, brain, nervous system, and skin d. 50% to 90% absorbed, primarily in small intestines B. B Vitamin Intakes of North Americans 1. Typical diets contain plentiful B vitamins 2. Many foods are fortified with B vitamins 3. Marginal deficiencies can occur with poor diet 4. Severe deficiencies are rare but can occur in older adults and alcoholics. C. B Vitamins in Grains 1. Milling of grains increases losses: removal of germ, bran, and husk, where many vitamins and minerals exist 2. Many grains are enriched in the U.S. (thiamin, riboflavin, niacin, folic acid, and iron) 3. Enrichment does not replace vitamin E, vitamin B-6, potassium, magnesium, fiber, and others 4. Regular consumption of whole grains is preferred over refined grains (see Fig. 8-18). 8.7 Thiamin (Vitamin B-1) A. Functions of Thiamin 1. Coenzyme form helps release energy from carbohydrates 2. Chemical reactions that make RNA, DNA, and neurotransmitters B. Thiamin Deficiency 1. beriberi (“I can’t, I can’t”) 2. Glucose cannot be metabolized to release energy 3. Symptoms a. Weakness b. Poor arm and leg coordination c. Loss of appetite d. Irritability e. Nervous tingling throughout body f. Deep muscle pain in calves g. Enlarged heart h. Sometimes severe edema 4. Vulnerable populations a. People living in regions where polished rice is staple food b. Low-income older adults c. Alcoholics (beriberi associated with alcoholism is called Wernicke-Korsakoff syndrome) C. Getting Enough Thiamin 1. Men and women typically meet or exceed needs. 2. Sources (proteins and grains groups have most foods with thiamin) a. Pork products b. Whole and enriched grains c. Legumes d. Milk e. Orange juice f. Organ meats g. Seeds h. Figure 8-19 presents food sources of thiamin 3. Adults with low-incomes and older adults may be at risk for marginal deficiency due to intake of highly processed and un-enriched foods. 4. Excess intake is rapidly lost in urine 5. No known toxicity; no UL 8.8 Riboflavin (Vitamin B-2) A. Functions of Riboflavin 1. Coenzyme form, flavin dinucleotide (FAD) and flavin mononucleotide (FMN) assist in energy yielding metabolism such as fatty acids (see Fig. 8-17). 2. Antioxidant role through support of glutathione peroxidase B. Riboflavin Deficiency 1. Ariboflavinosis 2. Symptoms a. Inflammation of tongue and mouth b. Cracking of tissue around the corners of the mouth (cheilosis—see Fig. 8-20) c. Eye disorders d. Sun sensitivity e. Confusion C. Getting Enough Riboflavin 1. Major Sources a. Milk products b. Enriched grains c. Meat d. Various greens e. Eggs 2. Average intakes are slightly above the RDA 3. Alcoholics risk deficiency due to poor diet 4. No known toxicity; no UL 8.9 Niacin (Vitamin B-3) A. Functions 1. Coenzyme, nicotinamide adenine dinucleotide (NAD) or nicotinamide dinucleotide phosphate (NADP) in energy metabolism 2. Synthesis of new compounds, especially of fatty acids (see Fig. 8-17) B. Niacin Deficiency 1. Pellagra: “rough and painful skin” (see Fig. 8-22) 2. Symptoms a. Early symptoms a. Poor appetite b. Weight loss c. Weakness b. Late symptoms (three Ds) a. Dementia b. Dermatitis (see Fig. 8-22) c. Diarrhea c. Death can occur if severe and untreated. 3. Deficiency was common (late 1800s–early 1900s) in parts of North America where corn was a staple of the diet 4. Bound niacin (ex: as is the case in corn) can be released by soaking corn in alkaline solution C. Getting Enough Niacin 1. Niacin sources (see Fig. 8-23) a. Poultry b. Beef c. Tuna/fish d. Wheat bran e. Asparagus f. Peanuts g. Coffee and tea h. Can synthesize niacin from tryptophan (60 mg tryptophan  1 mg niacin) 2. Average intakes double the RDA 3. Deficiency uncommon today except in alcoholics or people with rare disorders of tryptophan metabolism D. Avoiding Too Much Niacin 1. Toxicity from supplementation of nicotinic acid 2. Symptoms a. Headache b. Itching c. Increased blood flow to the skin (flushing) d. GI tract and liver damage possible 3. Sometimes large amounts are used under a doctor's supervision to treat cardiovascular disease 8.10 Vitamin B-6 (Pyridoxine) A. Functions of Vitamin B-6 1. Coenzyme, pyridoxal phosphate (PLP), in metabolism of amino acids and protein (see Fig. 8-17) 2. Amino acid metabolism for synthesis of non-essential amino acids (transfers NH2) 3. Converts homocysteine to methionine 4. Converts tryptophan to niacin 5. Roles in synthesis of neurotransmitters, white blood cells, and hemoglobin 6. Breakdown of stored glycogen to glucose B. Vitamin B-6 Deficiency 1. Affects multiple body systems 2. Symptoms a. Depression b. Vomiting c. Skin disorders d. Nerve irritation e. Decreased immune response f. Anemia 3. Vulnerable populations: alcoholics a. Metabolite of alcohol displaces vitamin B-6 coenzyme from enzymes b. Increased destruction of vitamin B-6 c. Decreased absorption of vitamin B-6 d. Decreased synthesis of coenzyme form of vitamin B-6 (liver destruction) C. Getting Enough Vitamin B-6 1. Vitamin B-6 sources (see Fig. 8-24) a. Animal products (e.g., meat, fish, and poultry) b. Ready-to-eat breakfast cereals c. Potatoes d. Milk e. Bananas f. Cantaloupe g. Broccoli h. Spinach i. Vitamin B-6 from animal sources is more absorbable than from plant sources 2. Average intakes exceed the RDA 3. Athletes may need more than RDA as they process larger amounts of glycogen D. Avoiding Too Much Vitamin B-6 1. Symptoms a. Irreversible nerve damage if 2-6 g/d for 2+ months b. Walking difficulties, hand and foot numbness 2. Toxicity occurs from supplementation 8.11 Pantothenic acid (Vitamin B-5) and Biotin (Vitamin B-7) A. Pantothenic Acid 1. Functions (see Fig. 8-17) a. Coenzyme form (coenzyme A, CoA) aids in release of energy from carbohydrates, fats, and protein b. Activates fatty acid for release of energy 2. Deficiency a. Nutritional deficiency is unlikely because pantothenic acid is widespread in foods b. Deficiency symptoms hidden among deficiencies of other B vitamins c. Vulnerable populations include alcoholics 3. Getting Enough Pantothenic Acid a. Rich sources (see Fig. 8-25) i. Sunflower seeds ii. Mushrooms iii. Peanuts iv. Eggs v. Meat vi. Milk vii. Many vegetables b. AI: 5 mg/d c. Average intakes meet the RDA d. No known toxicity, no UL B. Biotin 1. Functions a. Promotes synthesis of glucose, fatty acids, and DNA (adds CO2 in chemical reactions) b. Breaks down certain amino acids 2. Deficiency symptoms a. Scaly inflammation of the skin b. Changes in tongue and lips c. Decreased appetite, nausea, vomiting d. Anemia e. Depression f. Muscle pain g. Weakness h. Poor growth 3. Rich sources found in protein (see Fig. 8-26) a. Egg yolks b. Peanuts c. Cheese 4. Intestinal bacteria synthesize some biotin, making deficiency unlikely 5. Biotin bioavailability a. Avidin in raw egg whites binds biotin and inhibits its absorption b. Cooking denatures avidin so it does not bind biotin 6. Average intakes meet the RDA 7. No known toxicity; no UL 8.12 Folate (Vitamin B-9) A. Overview 1. Folate describes forms found in foods 2. Folic acid is synthetic form B. Functions of folate 1. DNA synthesis (specifically affects RBC synthesis) 2. Amino acid and homocysteine metabolism 3. Research is underway on the link between folate and cancer protection C. Folate Deficiency 1. Affects red blood cell division because DNA cannot form a. Macrocytic (large cells) or megaloblastic anemia (see Fig. 8-27) b. Megaloblasts are large, immature RBCs c. Decreased oxygen-carrying capacity 2. Maternal deficiency in first 28 days of pregnancy linked to neural tube defects a. All women of childbearing age should take 400 mcg/d of synthetic folate b. Be careful of supplements, should have no more than 100% DV for vitamin A during pregnancy due to risk of toxicity 3. Vulnerable populations a. Older adults a. Inadequate intake b. Decreased absorption b. Alcoholism: poor intake and absorption D. Getting Enough Folate 1. Folic acid is synthetic chemical form added to foods and present in supplements—more readily absorbed than natural folate 2. Folate, the form found naturally in foods, contains extra units of glutamic acid that must be removed before absorption a. Destroyed by heat and processing b. Vitamin C protects folate from degradation 3. Fortification program (1998) has increased average folate consumption in the United States by about 200 mcg/d and decreased rates of NTDs a. Pregnant women need 600 mcg DFE b. With fortification program, average intakes meet the RDA (non-pregnant) c. Fortification has decreased rates of neural tube defects by 15–30% in U.S. d. Fortification has been accompanied by decline in cardiovascular disease risk (drop in blood homocysteine) 4. Rich sources of folate a. Green leafy vegetables b. Organ meats c. Other vegetables d. Sprouts e. Dried beans f. Orange juice g. Fortified breakfast cereals h. Milk i. Bread j. Figure 8-28 presents sources of folate from MyPlate E. Avoiding Too Much Folate 1. Masks symptoms of vitamin B12 deficiency (enlarged RBCs) 2. UL: 1 mg synthetic form (folic acid) a. FDA limits non-pregnancy supplements to 400 mcg b. Food sources are less absorbable 8.13 Vitamin B-12 (Cobalamin or Cyanocobalamin) A. Overview 1. Family of compounds containing the mineral cobalt 2. Can be stored in the liver unlike other water-soluble vitamins; takes months for deficiency to surface 3. Only found in animal food sources 4. Requires intrinsic factor produced in stomach for absorption 5. Stomach’s ability to produce stomach acid and intrinsic factor decreases with age 6. Disruption of vitamin B-12 absorption leads to most deficiencies (see Fig. 8-29) B. Functions of Vitamin B-12 1. Folate metabolism, and therefore DNA synthesis 2. Maintains myelin sheath that insulates nerve fibers C. Vitamin B-12 Deficiency 1. Most deficiencies are result of lack of intrinsic factor rather than insufficient intake; necessitates megadose oral supplementation, injections, or nasal gel a. Pernicious (“leading to death”) anemia results from low vitamin B-12 absorption b. Macrocytic anemia c. Symptoms include weakness, sore tongue, back pain, apathy, nerve degeneration (tingling in extremities, weakness, paralysis, eventually death from heart failure) d. Affects 2% of older adults 2. Vulnerable populations a. Vegans (takes 20 years on a diet free of vitamin B-12 to show symptoms of deficiency) b. Elderly (acid production reduces with age) c. Breastfed infants of vegan mothers are at risk D. Getting Enough Vitamin B-12 1. Rich sources (see Fig. 8-30) are from animal products a. Meats (especially organ meats) b. Poultry c. Seafood d. Eggs e. Milk products f. Ready-to-eat breakfast cereal 2. Synthetic (crystalline) form found in ready-to-eat cereals and pills is not bound and is therefore more readily absorbed 3. Older adults and vegans should find a reliable synthetic source of vitamin B-12 4. Average intakes exceed the RDA 5. No known toxicity; no UL 8.14 Vitamin C (Ascorbic Acid) A. Functions of vitamin C 1. Collagen synthesis a. Highly concentrated in connective tissue, bones, teeth, tendons, and blood vessels b. Wound healing 2. Formation of other compounds a. Synthesis of carnitine b. Formation of two neurotransmitters, serotonin and norepinephrine 3. Antioxidant a. Reduce formation of cancer-causing nitrosamines b. May be effective in prevention of cancers including esophagus, mouth, and stomach c. Reactivating vitamin E 4. Absorption of iron a. Keeps iron in absorbable form as it travels through alkaline environment b. Seen with intakes of ≥75 mg vitamin C at a meal 5. Immune function a. Protect immune cells from being degraded b. Promotes proliferation of white blood cells c. Vitamin C in large quantities does not prevent colds but it may reduce symptoms B. Vitamin C Deficiency 1. Scurvy 2. Symptoms a. Weakness b. Poor wound healing c. Bone pain d. Fractures e. Bleeding gums f. Diarrhea g. Pinpoint hemorrhages (see Fig. 8-31) C. Getting Enough Vitamin C 1. Major sources (see Fig. 8-32) a. Citrus fruits b. Green pepper c. Cauliflower d. Broccoli e. Cabbage f. Strawberries g. Papayas h. Potatoes i. Ready-to-eat breakfast cereals j. Fortified fruit drinks 2. Average intakes (70–100mg/d) meet the RDA 3. Smokers need an extra 35 mg/d 4. High bioavailability D. Avoiding Too Much Vitamin C 1. Kidneys excrete excess 2. Consequences of 2000mg or more per day a. Inflammation of the stomach b. Diarrhea c. Risk of kidney stones d. Interference with medical tests 8.15 Choline and Other Vitamin-Like Compounds A. Overview 1. Now called an essential nutrient but not a vitamin 2. Not yet classified as vitamin B. Functions of Choline 1. Cell membrane structure a. Precursor of phospholipids b. Particularly important for health of brain tissue 2. Single-carbon metabolism a. Precursor to betain b. Involved in transfer of single-carbon groups in metabolism such as neurotransmitters, modifications of DNA during embryonic development, and metabolism of homocysteine 3. Nerve function and brain development a. Part of acetylcholine, associated with attention, learning, memory, muscle control, and other functions. b. Sphingomyelin contains choline and is part of myelin sheath 4. Lipid transport a. Component of lipoproteins (part of phospholipids) b. Inability to transport VLDL leads to lipid buildup in liver C. Getting Enough Choline 1. Widely distributed in foods (see Fig. 8-33) a. Soybeans b. Egg yolks c. Beef d. Cauliflower e. Almonds f. Peanuts 2. Can be synthesized from other nutrients to some extent 3. Average intakes do not meet AI, but there is a wide variation of individual requirements 4. Unknown whether dietary supply is essential for infants or children 5. Choline needed during pregnancy especially (prenatal vitamins do not contain choline) D. Other Vitamin-Like Compounds 1. Carnitine: transports fatty acids into mitochondria 2. Inositol: part of cell membranes 3. Taurine: part of bile acids 4. Lipoic acid: participates in carbohydrate metabolism; antioxidant E. All can be synthesized in the body F. May be needed in diet in certain circumstances 8.16 Dietary Supplements—Who Needs Them? A. Overview 1. Dietary Supplement Health and Education Act of 1994 a. Supplements include vitamins, minerals, herbs or botanicals, amino acids, or any dietary substance to supplement the diet which could be an extract or a combination of the latter ingredients listed. b. Any product intended to supplement the diet that contains one or more of the above 2. Annual sales of dietary supplements in the United States: $35–36 billion 3. FDA only closely regulates supplements if there is evidence of harm or illegal claim on label 4. Claims about a nutrient’s role in structure or function are allowed, but supplement makers cannot claim to prevent, treat, or cure a disease 5. Commonly cited reasons for taking supplements a. Reduce susceptibility to health problems b. Prevent heart attacks c. Prevent cancer d. Reduce stress e. Increase energy B. Should you take a supplement? 1. There is insufficient evidence to broadly recommend use of multivitamin and mineral supplements for the general population 2. Dietary supplements are not a substitute for a poor diet 3. Supplements do not provide phytochemicals and fiber present in whole foods 4. Broad use of fortified foods satisfies many nutrient needs 5. Megadosing can lead to toxicities 6. Supplement/medication interactions 7. Emphasis should be placed on consuming a nutrient dense varied diet as illustrated in Figure 8-35. 8. Table 8-6 outlines the population groups who are most likely to benefit from dietary supplements and how they could benefit. 9. Most cases of nutrient toxicity involve supplementation. C. Which supplement should you choose? 1. Nationally recognized brand that contains 100% of the DV for the nutrients present a. Take with meals b. Check the content of fortified foods eaten to avoid exceeding the UL c. Figure 8-36 explains how to understand a supplement label 2. Men and older women should take low-iron or iron-free to avoid iron overload 3. Somewhat exceeding the UL for vitamin D is likely a safe practice for adults 4. Avoid superfluous ingredients like a. PABA b. Hesperidins c. Inositol d. Bee pollen e. Lecithin f. Also avoid high doses of l-tryptophan, beta carotene, and fish oils Nutrition and Your Health: Nutrition and Cancer A. Overview 1. Cancer is the second leading cause of death in North American adults 2. Lung, colorectal, breast, and prostate cancers account for 50% of all cancer deaths (see Fig. 8-37). 3. Cancer is the uncontrollable division of cells that results from a DNA mutation 4. Tumor is a spontaneous new tissue growth that serves no physiological purpose a. Benign tumors are not cancerous and do not spread b. Malignant tumors are cancerous and can spread (metastasize) B. Detecting Cancer 1. Early detection of cancer is essential to survival and quality of life 2. CAUTION acronym a. Change in bowel or bladder habits b. A Sore that does not heal c. Unusual bleeding or discharge d. Thickening or lump in breast or elsewhere e. Indigestion or difficulty swallowing f. Obvious change in wart or mole g. Nagging cough or hoarseness 3. Investigate unexplained weight loss 4. Preventive testing a. Colonoscopy b. PSA tests c. Pap smears d. Regular breast exams C. Factors that Influence Development of Cancer 1. The cause of cancer is multi-factorial: genetics, environment, and lifestyle play a role 2. Genetic predispositions in colon, prostate, and breast cancers 3. Lifestyle and environmental exposures are critical factors in most cancers D. A Closer Look at Diet and Cancer 1. Overview a. Table 8-7 presents some food constituents that may have a role in cancer b. Links between fat/calorie intake and cancer c. Links between food constituents and cancer 2. Contribution of calorie and fat intakes to cancer risk a. Excess calories lead to obesity, which is a risk factor for all types except lung cancer b. Link between dietary fat and cancer is probably mediated by excess estrogen, which is produced by adipose tissue and promotes cancer c. Excess insulin production, which is a typical result of obesity, may also promote cancer d. NCI suggests lowering fat intake to 20% of calories if at high risk for cancer, although some scientists do not believe the evidence is strong e. Calorie restriction (70% of usual intake) results in 40% reduction in tumor development in animal studies, but this information is difficult to apply to humans 3. Cancer-inhibiting food constituents a. Antioxidants (e.g., carotenoids, vitamin E, vitamin C, and selenium) b. Phytochemicals c. Vitamin D is implicated in reduced risk of breast, colon, prostate, and other forms of cancer d. Calcium is linked to decreased risk for colon cancer E. Nutrition Concerns During Cancer Treatment 1. Minimize weight loss a. Poor nutrition status limits recovery b. Treatments may cause fatigue, mouth sores, dry mouth, taste abnormalities, nausea, and diarrhea 2. Prevent nutrient deficiencies 3. Suggestions a. Encourage consumption of any foods that are tolerated b. Cool, non-acidic liquids and soft, mildly-flavored foods are well-accepted c. Small, frequent meals d. High nutrient and calorie density e. Liquid nutritional supplements f. Safe food handling due to immunosuppression F. Guidance for Cancer Prevention 1. Be as lean as possible without becoming underweight 2. Be physically active for at least 30 minutes every day 3. Avoid sugary drinks 4. Eat more of a variety of fruits and vegetables, whole grains, and legumes 5. Limit consumption of red meats 6. Consume alcohol in moderation (if at all) 7. Limit consumption of salty foods and foods processed with salt 8. Do not use supplements to protect against cancer BEST PRACTICES: TEACHING STRATEGIES, DEMONSTRATIONS, ACTIVITIES, ASSIGNMENTS, AND MORE 1. Assign students the Rate Your Plate activity and use as a springboard to discuss the benefits of daily use of a fortified breakfast cereals. 2. Ask students to bring to class the vitamin supplements they use, or you can provide a variety of brands (brand names and generic). Ask students to evaluate them using the guideline that no vitamin should be present in amounts greater than 150% of the Daily Value. Divide the supplements into those that meet the guidelines and those that exceed them. Discuss the implications of consuming vitamins in too-high quantities. 3. Next, compare the cost of name brands to generic ones. Have students determine how much money they would save by purchasing generic brands. Do this as a general class activity. Make a list of generic brands on the board and their prices and a similar list in a column next to it of the name brands. Do a price comparison. Lastly, discuss situations and conditions that would warrant the use of supplemental vitamins. 4. Most vitamins have an interesting history. Have each student prepare a background report on the discovery and isolation of one vitamin. These could be handed in and graded or presented as oral reports. 5. During class discussion, have students describe various food preparation and storage techniques that should be used to preserve the water-soluble vitamin content of fruits and vegetables. 6. Fortified foods have become increasingly common in the U.S. Ask students to survey cereal products found in the supermarket and compare the vitamin content in at least eight. Which cereal would they choose if they wanted to get the most vitamin nutrition? 7. Have students write the name of each vitamin on an index card. On the back, they will list one to three key functions of that vitamin; food sources; deficiency name, if appropriate; deficiency symptoms; and toxicity symptoms. Have students study these index cards in pairs until they can recall the information about each vitamin. 8. Before class, write the name of each vitamin on a piece of paper, index card, or "post-it." If you use paper or an index card, remember to take stickpins or tape to class to fasten the card/paper on students' backs. Secure one card/paper/post-it on the back of each student. Have students circulate throughout the room asking other students questions about the vitamin posted on their back. Only yes and no questions are permitted, for example, "Am I involved in blood clotting?" and "Are green vegetables good food sources of me?" Only two questions can be asked of any person. After asking two questions of a person, students must move to someone else. Continue the game until everyone correctly identifies the vitamin they are. 9. Place posters with names of vitamins and minerals around the room. Give students index cards describing symptoms of deficiencies and excesses. Have them match symptom cards with the appropriate vitamin or mineral. 10. Assign students to prepare a skit based on a job interview. Ask the “vitamin applicant” what they can do for “the company,” how they work, etc. 11. Post lists of foods around the room. Have students determine the key vitamin(s) present in each group of foods. 12. Bring several recipes to class. Ask students to evaluate the ingredients—what are the phytochemicals in this recipe? Instructor Manual for Wardlaw's Contemporary Nutrition Anne M. Smith , Angela L. Collene 9780078021374, 9781260092189