Nutrients Involved in Body Defenses PDF

Chapter 10 Nutrients Involved in Body Defenses 1  The Immune System Collection of diverse tissues: Skin Intestinal cells White blood cells Lymphoid tissue Work together to: Prevent infection Break down aged, dying cells Remove ab...

Chapter 10 Nutrients Involved in Body Defenses 1  The Immune System Collection of diverse tissues: Skin Intestinal cells White blood cells Lymphoid tissue Work together to: Prevent infection Break down aged, dying cells Remove abnormal cells 2 Skin Almost continuous barrier surrounding the body Essential fatty acids, vitamin A, niacin, and zinc help maintain skin health. Skin lesions provide an opening for bacteria to penetrate. Nutrient deficiencies weaken the integrity of the skin. Vitamin A deficiency lowers enzyme lysozyme, needed to kill bacteria. 3 Intestinal Cells 1. Cells of small and large intestines: Packed close together Form barrier to microorganisms 2. Gut-associated lymphoid tissues (G A L T): Assists cells of GI tract in keeping pathogens from entering bloodstream 3. Nutrients: Adequate protein, vitamin A, vitamin B-6, vitamin B-12, vitamin C, folate, and zinc 4. Nutrient deficiencies: Cause intestinal cells to break down Lead to diarrhea and bacteria in bloodstream 4 White Blood Cells Cell-mediated immunity Phagocytes: monocytes (precursors to macrophages), neutrophils, and eosinophils. Phagocytosis: cells engulf, ingest, digest substances, including microorganisms, destroy pathogens via lysosomes. Antibody-mediated immunity Lymphocytes produce antibodies in response to foreign proteins (antigens). Antibodies mark invaders for destruction by other immune cells. 5 Lymphoid Tissue Thymus, bone marrow, spleen, lymph nodes, and other clusters of immune cells throughout the body Thymus: With bone marrow, helps mature white blood cells Active in infancy through adolescence, tapers off during adulthood Spleen: Contains many macrophages, removes foreign proteins, dead, damaged cells from blood Clusters of lymphoid tissue: Mostly around lungs and GI tract (GALT) activity 6 Two Categories of the Immune Response Innate (nonspecific): Born with this defense Physical, chemical defenses keep foreign substance out of the body. Adaptive (specific): Developed over time as exposed to individual pathogens 7 Innate (Nonspecific) Immune Response Inflammatory response-macrophages: Activated by ingesting foreign protein, pathogen Release cytokines, cause swelling and fever, usually short lived Chronic, low-level inflammation linked to ailments: Refined carbohydrates, added sugars, solid fats, and overall calories thought to promote inflammation Fruits and vegetables, plant proteins, unsaturated fats from plant oils and fish, whole grain associated with lower inflammation, and lower risks of chronic diseases 8 Adaptive (Specific) Immunity Response Lymphocytes: Produce antibodies Bind to antigens Mark foreign proteins and microorganisms for destruction by white blood cells May take several days or weeks to eradicate pathogen Creates template to “remember” for future exposure 9 Dietary Patterns That Support the Immune Response Epithelial tissues form barriers to the environment vitamin A, several B vitamins, vitamin C, and zinc White blood cells destroy pathogens. vitamins A, C, D, and E, as the mineral zinc Antioxidant defense systems vitamins C and E, carotenoids and other phytochemicals, and minerals such as selenium and zinc Gut microbes influence human health. whole food prebiotics and probiotics 10 Nutrients That Support the Immune Response Constant cell synthesis requires Destruction of pathogens: steady nutrient intake. Minerals support cell structure Formation of new cells: and help destroy pathogens. Protein supplies building blocks. Zinc and copper: structural roles and critical for the synthesis of Vitamin B-6 is involved in amino white blood cells. acid metabolism to make new cell proteins. Iron and zinc: for production of enzymes used by white blood Folate, vitamin B-12, and iron are cells to destroy pathogens. needed for D NA synthesis. 11 Vitamins A and D Regulate Gene Expression Active forms of vitamins A and D: Bind to receptors on D NA to switch various genes on or off Exert control over immune system activity at the genetic level Ability of vitamin D to limit the action of certain white blood cells. Linked to decreased risk of autoimmune diseases 12 Antioxidant Nutrients Protect Immune Cells Vitamin C, Vitamin E, Selenium: Antioxidant capabilities Protect immune cells from being damaged by oxidation reactions used to destroy pathogens White blood cells utilize oxidation to kill pathogens. May increase proliferation of immune cells Regulate the expression of proteins involved in the immune response 13 Table 10-1: Micronutrients That Support Body Defenses 1 Nutrient Primary Roles in Immunity Vitamin A Maintains the health of epithelial cells Contributes to function of mucus-secreting cells Supports activity of white blood cells Vitamin B-6 Maintains the health of epithelial cells Aids in synthesis of white blood cells Production of proteins involved in the immune response Vitamin B-12 Maintains the health of epithelial cells White blood cell formation and activity Vitamin C Protects immune cells from oxidative damage as an antioxidant Stimulates production and activity of white blood cells Vitamin D Modulates gene expression in white blood cells Possibly prevents autoimmune diseases Vitamin E Protects immune cells from oxidative damage May protect against age-related declines in immune function 14 Table 10-1: Micronutrients That Support Body Defenses 2 Nutrient Primary Roles in Immunity Folate Maintains the health of epithelial cells White blood cell formation and activity Zinc Development and function of white blood cells Supports ability of cells to use oxidation reactions to kill pathogens Iron Used in function of white blood cells Supports ability of cells to use oxidation reactions to kill pathogens Copper Production of white blood cells, particularly phagocytes Selenium Protects immune cells from oxidative damage Involved in the expression of cytokines that regulate the immune response 15 Oxidative Stress Oxidative stress: Imbalance between production of reactive compounds and body’s ability to protect against their adverse effects Reduction: gain of a negatively charged electron. Oxidation: loss of a negatively charged electron. Sharing electrons in outer shell makes strong bonds between atoms or molecules. Oxidation of these bonds produces stable compounds. 16 Free Radicals Unstable atoms with unpaired electrons in the outermost shell A weak bond between an atom or molecule produces a possible molecule or atom left with an unpaired electron in its outer shell. Overproduction of free radicals can be harmful to healthy cells. Free radicals damage specific structures, such as DNA, within cells. Antioxidants defend against the adverse effects of free radical. 17 Antioxidant Defenses Body has two defense mechanisms: Enzyme systems and antioxidant chemicals Work together to limit free radical formation. 1. Enzyme Activity 2. Dietary Antioxidant Requires the presence of minerals such “Substance in foods that significantly as selenium, manganese, zinc, iron, and decrease adverse effects of reactive species copper such as reactive oxygen and nitrogen species on normal physiological function in Antioxidant enzymes include superoxide humans” dismutase, glutathione peroxidase, and catalase. Has the ability to prevent or repair damage caused by oxidation Increased consumption of fruits and vegetables that supply antioxidant vitamins, minerals, and phytochemicals to support the body’s defenses against reactive molecules. 18 Figure 10-5: Oxidative Stress Linked to Many Chronic Diseases kurhan/123RF Access the text alternative for these images 19 Nutrients for Immune Function 20 Vitamin A – Fat soluble Forms of Vitamin A Preformed vitamin A: Retinoids Three active forms: 1. Retinol, 2. Retinal, 3. Retinoic acid Dietary source - animal products Ssupplements - Retinyl acetate or retinyl palmitate 21 Carotenoids Plants contain pigments called Carotenoids that are provitamins carotenoids: can be converted into vitamin A: Phytochemicals with health- β-carotene promoting chemicals α-carotene Precursors of vitamin A have β-cryptoxanthin antioxidant properties. Other carotenoids may have health benefits: Lycopene Zeaxanthin Lutein 22 Functions of Vitamin A: Health of Epithelial Cell Health and Immune Function Epithelial cells Line internal and external surfaces of eyes, skin, lungs, intestines, stomach, vagina, urinary tract, and bladder Important barriers to infection Retinoic acid required for immature epithelial cells to develop into mature, functional cells Vitamin A also supports the activity of T-lymphocytes (T-cells). 23 Functions of Vitamin A: Eye Health and Vision Night Blindness Vitamin A functions in light–dark and color vision. Vitamin A deficiency: lose ability to see under low-light conditions. Retina: lining of cells (rods, cones, and nerve cells). Light entering the eye reaches the retina. Rods and cones require vitamin A (retinal) for normal function. Rods detect black and white, responsible for night vision. Cones are responsible for color vision. 24 Carotenoids and Age-Related Macular Degeneration Macula: central area of retina Responsible for detailed central vision Contains carotenoids lutein and zeaxanthin in high concentrations—impart a yellow color Age-related macular degeneration: Cause of blindness in older adults Higher intakes of carotenoids may help to prevent or slow its progression. Green leafy vegetables are rich sources of lutein and Figure 10-7: The blurry center of the zeaxanthin. image simulates the vision of a person with macular degeneration. 25 Functions of Vitamin A: Growth, Development, and Reproduction Binds to receptors on D NA to increase synthesis of a variety of proteins, some required for growth Functions in differentiation and maturation of cells, ultimately forming tissues and organs Assists with breakdown and formation of healthy bone tissue Aids in male sperm production and normal reproductive cycle in women 26 Functions of Vitamin A: Cardiovascular Disease Prevention Carotenoids may inhibit oxidation of low-density lipoproteins (L D Ls). Consume a total of at least five servings of a combination of fruits and vegetables per day. As part of an overall effort to reduce the risk of cardiovascular disease 27 Functions of Vitamin A: Cancer Prevention Vitamin A: Essential role in cellular differentiation and embryonic development Dietary patterns rich in provitamin A carotenoids Associated with lower risk of skin, lung, bladder, and breast cancers Toxicity risk in a megadose of vitamin A through supplement use 28 Vitamin A Deficiency Results in three main problems: 1. Impaired vision. Leading cause of blindness worldwide 2. Weakened immune function 3. Stunted growth. In severe cases, Vitamin A deficiency contributes to death. 29  Vitamin A Deficiency : Xerophthalmia Mucus-forming cells deteriorate, and lose function 1. Leads to xerophthalmia (dry eye) and blindness 2. Hyperkeratosis, skin cells produce too much keratin, blocking hair follicles and causing “gooseflesh” or “toad skin” appearance. Excessive keratin causes the skin to be hard and dry. Dr. Alfred Sommer 30 Getting Enough Vitamin A American dietary patterns contain plentiful R D A: expressed in retinol sources of preformed vitamin A. activity equivalents (RAE). Preformed vitamin A (retinol, retinal, Adult male, 900 μg per day. and retinoic acid), 70% of American Adult female, 700 μg per day. dietary pattern Daily Value = 900 μg per day. Food sources: liver, fish, fish oils, fortified milk, butter, yogurt, and eggs. Reserves are stored in liver. 31 Getting Enough Carotenoids β-carotene: dark green and yellow-orange vegetables and fruits. Lutein and zeaxanthin: green leafy vegetables. Lycopene: tomato products. 32  Inuits long knew and explorers soon learned to avoid eating the liver of polar Avoiding Too Much Vitamin A bears. Just 4 oz of polarbear liver will deliver a Intakes in excess of the UL for vitamin A: toxic dose of 675,000 RAE of vitamin A. Liver toxicity and increased risk of hip fracture Poor pregnancy outcomes, birth defects Fetal malformations and spontaneous abortions Women of childbearing age: Limit intake of preformed vitamin A to no more than of Daily Value. 33 Avoiding Too Much Carotenoids Excess dietary consumption, no toxic effects. Hypercarotenemia: high carotenoid concentration in blood. Too many carrots or β-carotene supplements/pills As little as four to five large carrots daily can produce hypercarotenemia. Skin turns yellow-orange, particularly the palms of the hands and soles of the feet. Taking a break from carrots, squash, and pumpkins will turn the skin back to normal. 34  Vitamin C (Ascorbic Acid) Water Soluble Functions of Vitamin C Formation of body proteins: Supporting body defenses: Collagen synthesis; found in Antioxidant connective tissue, bone, teeth, Vital for immune function tendons, and blood vessels May decrease formation of Formation of other compounds: carcinogen nitrosamines in Carnitine synthesis; transports fatty stomach acids Aids reactivation of vitamin E Serotonin and norepinephrine Absorption of iron: synthesis Increases iron absorption 35 Vitamin C Deficiency Scurvy Reduces collagen synthesis Bruising, bleeding gums, petechiae, and poor wound healing James Lind, a British physician discovered citrus fruits prevented and restored the health of sailors by conducting “human clinical trials” 36 Getting Enough Vitamin C Adult R DA: 75 mg per day for women 90 mg per day for men Smokers: Need extra 35 mg because of increased oxidation by tobacco smoke in lungs Average U.S. consumption: 70 to 100 mg per day. 37 Food Sources of Vitamin C Citrus fruits, papayas, cauliflower, and other vegetables of vitamin Ready-to-eat breakfast cereals and potatoes Five to nine servings of fruits and vegetables can easily provide enough vitamin C to meet the R DA. Vitamin C is rapidly lost in processing and cooking as it is unstable in the presence of heat, iron, copper, or oxygen and is water soluble. Maria Uspenskaya/Shutterstock 38 Avoiding Too Much Vitamin C UL is 2,000 mg per day. Increases iron absorption. Avoid if diagnosis hemochromatosis. Kidneys rapidly excrete vitamin C when intakes exceed 100 mg per day. GI distress - Stomach inflammation and diarrhea May interfere with medical tests for diabetes or blood in the feces 39 Vitamin E – Fat Soluble Functions: Identified as essential for rat fertility, 1920s α-tocopherol is biologically active form Vitamin E Functions 1. Antioxidant 2. Formation of muscles 3. Formation of central nervous system 4. Maintains nervous tissue and immune function 40 Vitamin E as an Antioxidant Fat-soluble vitamin: Found in adipose tissue and cell membrane Membrane lipids are polyunsaturated fatty acids (P U FA). P U FAs are susceptible to oxidative attack. Vitamin E donates electrons or hydrogens to free radicals to make cell more stable. Important in areas exposed to high levels of oxygen (R B Cs and lungs) 41 Vitamin E: Deficiency Rare because primary source of Vitamin E is plant oils Populations at risk: Preterm infants as transfer of vitamin E from mother occurs late in pregnancy Oxidative damage could cause red blood cell membranes to break (hemolysis). Smoking destroys vitamin E in lungs. Fat-malabsorption disorders or very low-fat diets 42 Getting Enough Vitamin E Only synthesized by plants Good sources include: Salad oils Best sources: plant oils Margarines Shortening R DA for adults: Fortified cereals 15 mg per day of α-tocopherol Nuts and seeds D V on labels is 15 mg. The avocado in guacamole and the oil in the tortilla chip are good sources of vitamin E. Andrew Bret Wallis/ BananaStock/Getty Images 43 Avoiding Too Much Vitamin E UL is 1,000 mg per day. Megadose do not provide significant health benefits or prevent oxidative damage. Not stored in the liver—stored in fat tissue Excess can interfere with vitamin K and anticoagulant medications (Coumadin and aspirin). Dietary Supplements Risk of drug interference and prolonged bleeding Can produce nausea, gastrointestinal distress, and diarrhea 44  Selenium (Se) Functions: Trace mineral Aids glutathione peroxidase: Antioxidant enzyme: chemically converts dangerous peroxides to water. Spares vitamin E and helps maintain cell membrane integrity Part of thyroid hormone activation 45 Selenium Deficiency The selenium content of foods is Strongly dependent on the selenium content of the soil where plants are raised or animals graze Low blood levels are linked to an increased risk of some types of cancer specifically prostate Symptoms: muscle pain and wasting heart damage, and thyroid dysfunction. 46 Getting Enough Selenium R D A and D V: 55 μg per day for adults. Adults generally meet selenium needs. Food Sources of Selenium Brazil nuts, fish, meat and organ meats, shellfish, and eggs Some grains and seeds grow in selenium-rich soil. Avoiding Too Much Selenium UL is 400 μg. Selenium toxicity has not been reported from food sources. Supplementation for long periods of time is toxic. Toxicity signs: hair loss, weakness, nausea, vomiting, and cirrhosis. 47 Functions of Zinc D NA synthesis and function Protein metabolism, wound healing, and growth Development of bones and reproductive organs Storage, release, and function of insulin Cell membrane structure and function Component of superoxide dismutase, an antioxidant enzyme that aids in the prevention of oxidative cell damage White blood cell formation 48  Zinc: Deficiency Children: Growth, sexual development, and learning ability hampered Adults: Acne-like rash Diarrhea Lack of appetite Delayed wound healing Impaired immune function Reduced or altered sense of taste and smell Hair loss 49 Critical Thinking: Zinc Zinc deficiency has been associated with the consumption of unleavened bread when whole grain flour is used in Middle Eastern countries. Phytates or Phytic acid found in whole grains bread, beans, nuts, grains, and seeds - binds zinc and decreases its bioavailability. Forms an insoluble complex when bound to calcium, zinc, and iron leading to deficiencies when soil contains high hadynyah/Vetta/Getty Images phytate phosphorous. 50 Getting Enough Zinc UL: 40 mg per day. Sources: Toxicity from zinc supplements and overconsumption of zinc-fortified Animal-protein foods foods 80% provided by meat, fish, Interferes with copper metabolism poultry, fortified cereal, and dairy products Intakes over 100 mg result in diarrhea, cramps, nausea, vomiting, loss of appetite, and R DA: depressed immune system 11 mg for men function 8 mg for women D V: 11 mg 51 Phytochemicals Source -Plant foods are complex mixtures of energy-yielding macronutrients, vitamins, minerals, fiber and phytochemicals. Dietary Guidelines to Eat a variety of fruits, vegetables, and whole grains. 52 Antioxidant Phytochemicals 1. Carotenoids: β -carotene: yellow-orange colors in sweet potatoes, winter squash, and carrots. Lycopene: found in tomatoes, watermelon, and pink grapefruit. Lutein and zeaxanthin found in leafy greens, squash, and yellow corn. 2. Anthocyanins: red, blue, and purple pigments in berries. 3. Polyphenols: the largest group of phytochemicals. Flavonoids: blueberries, chocolate, citrus fruits, and raspberries. 53 Functions of Phytochemicals Variety of beneficial actions: Antibacterial or antiviral properties Influence blood pressure or blood clotting Variety of mechanisms to reduce risk of: Cardiovascular disease Cancers Type 2 diabetes Neurodegenerative diseases 54 Pre and Probiotics and the Immune System Microorganisms are used to produce food and beverages. Fermentation: Alcohol, bread, cheese, fermented soy, and yogurt 1. Yeast – alcohol, bread. 2. Lactic acid bacteria—strains of bacteria that produce lactic acid from the fermentation of dairy products. Consumption of probiotics and prebiotics linked to prevention and treatment of: Diarrhea, respiratory infections, vaginal and urinary tract infections, allergies, and many autoimmune diseases 55 The Gut Microbiota Is a Diverse Community Human gut: At birth is sterile Soon exposed to a community of microorganisms, colonizing GI tract Microbiota varies from person to person. 500 different strains identified in the human colon Most have about 160 strains. Microbiome: Entire collection of microorganisms, their genes, and environment Depends on a variety of factors: genetics, age, geographic environment, diet, and lifestyle factors Many health benefits 56 Microbiome There are 1010-11 bacterial cells per gram of human feces The microbiome weighs in at estimated 500 g. Microbiome is passed to child at birth but evolves to unique individual makeup. Microbiome produces: 1. Short-chain fatty acids (SCFAs) 2. Amino Acids 3. Vitamin K 4. B-vitamins Walker, A.W., Hoyles, L. Human microbiome myths and misconceptions. Nat Microbiol 8, 1392–1396 (2023). https://doi.org/10.1038/s41564-023-01426-7 57 “Bugs” That Support Immune Function Healthy gut microbiota is crucial for proper immune system development and maintenance. Exposure of GALT to microorganisms promotes the maturation of immune cells. Immune system cells “learn” to recognize and differentiate between what is harmful and what is not. Probiotics reinforce the integrity of the GI tract. Provide a barrier against pathogen invasion Enhance immune function by transiently altering the composition of the microbiota Bind to pathogens or secrete substances that kill them 58 Preventing and Treating Infectious Diseases Use of Probiotics – Reduction of GI conditions and diarrhea: Most extensively studied benefit of probiotics Prevent or treat episodes of acute infectious diarrhea Also useful for the prevention or treatment of antibiotic-associated diarrhea. C. Diff. Chronic or repeated use of antibiotics disturbs the microbiota and wipes out the microbiome. Treatments: Probiotics Yogurt - Activia Fecal Transplant – “Healthy microbiome 59 Allergies and Autoimmune Diseases Alterations in microbiota may contribute to the development of allergies and autoimmune diseases. Hygiene hypothesis: Reduced exposure to microorganisms in the environment (such as overuse of antibacterial soaps and antibiotics) impairs the proper development of the immune system, making a person more susceptible to allergies and autoimmune diseases. C-section vs Natural birth – exposure to the mothers microbiome occurs by passing through the birth channel 60 Prebiotics 1. Should make it to colon without being degraded by digestive enzymes or stomach acid. 2. Should be fermentable by microbes living in intestine 3. Should work selectively on strain of beneficial bacteria Natural dietary sources: Leeks, asparagus, chicory, Jerusalem artichoke, garlic, artichoke, onion, wheat, oats, bananas, and soybeans Evidence supports whole food intake and dietary patterns rich in prebiotic and probiotic food sources. 61 Probiotics Natural dietary sources: Fermented dairy products, including yogurt, cheese, buttermilk, and kefir Nondairy alternatives include fermented soy products (for example, soy, miso, and tempeh), fermented vegetables (for example, sauerkraut or kimchi), and juices or other foods with added live cultures. Look for brands of yogurt that are labeled with the voluntary statement “contains live and active cultures.” Heat inactivates live cultures; freezing does not. 62 Prebiotic and Probiotic Supplementation 1. Lack of solid scientific information 2. Risk of harmful effects is greater in people with severe illnesses or compromised immune systems. 3. Infections, production of harmful substances, contamination, and transfer of antibiotic resistance genes 63 Study Questions 64 Defending the Body Against Pathogens 1. Describe two ways the GI tract assists the immune system. 2. What is the process by which cells can engulf particles, such as bacteria and fungi? What types of cells perform this function? 3. Differentiate between innate immunity and adaptive immunity. 4. What is the inflammatory response? What dietary patterns lead to chronic, low levels of inflammation? Protecting the Body From Oxidative Damage 1. What happens to electrons during the processes of reduction and oxidation? 2. What is a free radical? Why are free radicals thought to be harmful to cells? 3. How do antioxidant chemicals reduce cellular damage? 65 Vitamin A (Retinoids) and Carotenoids 1. What are the consequences of vitamin A deficiency? 2. How are the carotenoids related to vitamin A? 3. Name two carotenoids and identify a good food source of each. 4. List two rich food sources of retinoids. 66 Vitamin C (Ascorbic Acid) 1. How does the antioxidant role of vitamin C assist the immune system? 2. How do the signs of vitamin C deficiency relate to the many roles of the vitamin discussed in this chapter? 3. Why are fresh foods the best sources of vitamin C? Vitamin E (Tocopherols) 1. How does vitamin E work to prevent oxidative damage? 2. What are some rich food sources of vitamin E? 3. Why are infants who are born preterm, individuals who smoke, and people with fat-malabsorption disorders particularly susceptible to oxidative damage to cell membranes? 4. What are the possible results of vitamin E toxicity? 67 Selenium 1. How does selenium participate in the body’s antioxidant defenses? 2. What other functions does selenium play in the body? 3. What are the signs of a selenium deficiency? 4. What food groups are the best sources of selenium? 5. What are the signs of selenium toxicity? Zinc 1. List three good sources of zinc. 2. What are the consequences of zinc deficiency? 68 1. Antioxidant Phytochemicals 2. Name three phytochemicals that function as antioxidants. 3. Which food groups contain rich sources of antioxidant phytochemicals? 4. Other than yogurt, list two food sources of probiotic microorganisms. 5. Describe two ways probiotic microorganisms may work to support immune health. 6. Based upon the state of the science, are whole food sources or supplements of prebiotics and probiotics currently recommended? 69 Chapter 7 Part 1 Energy Balance 1  Dietary Patterns Almost 75% of adults are overweight or obese. From early to middle adulthood, the majority of adults gain about 1.1–2.2 lb per year. 60% of adults are affected by obesity-related chronic diseases. Most reliable and successful weight loss comes from a: commitment to lifestyle behaviors that improve dietary and physical activity patterns combination of improved energy balance, increased physical activity, and behavior modification © McGraw Hill, LLC 2  Obesity Epidemic © McGraw Hill, LLC  Obesity Epidemic - 2020 © McGraw Hill, LLC Globesity Source: CDC Behavioural Risk Factor Surveillance System. Access the text alternative for slide images. 5  Energy Balance Energy balance: The relationship between energy intake and energy expenditure 1. Energy equilibrium: When calories consumed matches the amount of energy expended 2. Positive energy balance: Energy intake exceeds energy expenditure and results in weight gain 3. Negative energy balance: Energy intake is less than energy expenditure and weight loss occurs 6  Energy Balance 2 Positive energy balance is desired during growth stages: Pregnancy Infancy Childhood Adolescence Aging does not cause weight gain. Negative energy balance is desired in adults when body fatness exceeds healthy levels. Not recommended during growth stages as it can impair normal growth pattern 7 Energy Intake Amount of energy in food or beverages can be estimated using nutrient databases or software Calorie values are derived directly by using a bomb calorimeter. Calorie content can also be calculated by determining the grams of the energy-providing macronutrients and alcohol and multiplying these compounds by their physiological values. 8 Energy Expenditure Thermogenesis Thermogenesis is a metabolic process in which the body burns calories to produce heat. The body uses energy for 3 main purposes: 1. Basal metabolism 2. Thermic Effect of Food - Digestion, absorption, and processing of ingested nutrients 3. Physical activity - variable A minor form of energy output is expended during fidgeting or shivering 9 Basal Metabolism 1 Basal metabolism (BMR) 1. Minimum amount of energy expended in fasting to keep a resting, awake body alive in a warm, quiet environment 2. Accounts for about 60 to 80% of total energy expenditure 3. Processes involved include beating of heart, respiration of lungs, and activity of other organs If a person is not fasting or rested, the resting metabolism is used (R M R). BMR and RMR are expressed as the number of calories burned per unit of time, average: Women is 0.9 kcal/kg per hour Men is 1.0 kcal/kg per hour 10 Basal metabolism (BMR) BMR peaks at one year of age and declines until age 20. BMR remains stable from ages 20 to 60. BMR declines again in older adulthood 11 Basal Metabolism 2 Factors that increase basal metabolism: Greater muscle mass Larger body surface Male gender Body temperature Higher than normal secretions of thyroid hormones Nervous system activity Growth stages Caffeine and tobacco use Recent exercise 12 Basal Metabolism 3 Factors that decrease basal metabolism: 1. Lower than normal secretions of thyroid hormones 2. Restricted calorie intake 3. Less body surface area and muscle mass 4. Aging after age 30 years 13 Energy for Physical Activity Physical activity increases energy expenditure above basal needs by 25 to 40%. Being active or inactive determines much of our total energy expenditure Climb stairs rather than take elevator Walk rather than drive Stand in a bus rather than sit The increased rate of obesity in North America is caused in part by our inactivity. 14 Thermic Effect of Food Thermic effect of food (TEF) 1. Energy used to digest, absorb, transport, store, and metabolize 2. Accounts for 5 to 10% of energy consumed 3. Influenced by food composition TEF for protein rich meals is 20 to 30% TEF for carbohydrate rich meals is 5 to 10% TEF for fat rich meal is 0 to 5% TEF for alcohol is 20% 4. Also influenced by size of meal Larger meals have higher TEF 15  Critical Thinking: T E F A few foods, such as celery, have been hypothesized to use more calories for TEF than they contain, making them a negative calorie food. Despite its recurring popularity in fad diets, there is no scientific evidence supporting the idea that any food, including celery, is calorically negative. Although celery still yields some calories, it Ingram Publishing/Getty Images remains an excellent choice to include in a healthy dietary pattern. Are celery, and other vegetables, considered a low or high energy- dense food option? © McGraw Hill, LLC 16 Adaptive Thermogenesis 1 Thermogenesis Change in the BMR in response to environmental stresses. Small contribution to total energy expenditure Produced when body expends energy for non-voluntary physical activity Triggered by extreme cold, overfeeding, trauma, starvation Activities include fidgeting, shivering, maintaining muscle tone, holding body upright 17 Adaptive Thermogenesis 2 Brown adipose tissue is a specialized form of fat tissue Newborns have higher proportion of brown fat Participates in thermogenesis Contains many capillaries and mitochondria Found in small infants and hibernating animals 18 Measuring Energy Expenditure 1 Energy used by the body can be measured by: Direct calorimetry Indirect calorimetry Energy used can be estimated based on: 1. Height 2. Weight 3. Physical activity 4. Age 19 Measuring Energy Expenditure 2 Direct calorimetry Estimates energy expenditure by measuring amount of heat released by the body About 60% of energy the body uses leaves as heat Heat release is measured by placing person in insulated chamber surrounded by layer of water Change in temperature determines amount of energy person expended 20 Measuring Energy Expenditure 3 Indirect calorimetry Involves collecting expired air Predictable relationship between body’s use of energy and amount of oxygen consumed and carbon dioxide produced Data tables can show energy costs of different exercises 21  Measuring Energy Expenditure 4 Estimated Energy Requirements (EERs) are measurements that can estimate energy needs based on: AGE = Age in years P A = Physical Activity Estimate (see table on next slide) W T = Weight in kilograms (pounds per 2.2) H T = Height in meters (inches per 39.4) Men 19 and older: EER = 662 - (9.53  AGE) + PA (15.91 WT) + (539.6  HT)  Women 19 and older: EER = 354 - (6.91 AGE) + PA (9.36  WT) + (726  HT) 22 Physical Activity (PA) Coefficient Estimates 23  Estimating Energy Requirements The following is a sample calculation for a male who is 25 years old, 5 ft 9 in. (1.75 m), and 154 lb (70 kg) and has a highly active lifestyle. His E E R is calculated as follows: EER = 662 − (9.53  25) + 1.25  (15.91 70 + 539.6  1.75) = 2997 kcal The next equation is a sample calculation for a female who is 25 years old, 5 ft 4 in. (1.62 m), and 120 lb (54.5 kg) and has an active lifestyle. Her E E R is as follows: EER = 354 − (6.91 25) + 1.27  (9.36  54.5 + 726  1.62) = 2323 kcal © McGraw Hill, LLC 24 Energy Expenditure Estimates by Age and Activity Children Sedentary → Active 2-3 years 1000 calories → 1400 calories Females Sedentary → Active 4-8 years 1200 calories → 1800 calories 9-13 1600 → 2200 14-18 1800 → 2400 19-30 2000 → 2400 31-50 1800 → 2200 51+ 1600 → 2200 Males Sedentary → Active 4-8 years 1200 calories → 2000 calories 9-13 1800 → 2600 14-18 2200 → 3200 19-30 2400 → 3000 31-50 2200 → 3000 51+ 2000 → 2800 25 Estimating Body Weight and Composition In the past, weight-for-height tables were the method used to determine if weight was healthy The focus has shifted from these tables to considering components of body weight and their relative proportions. Now recommended to evaluate: Total body fat Location of body fat Weight-related medical problems 26 Body Mass Index Weight-for-height standard Convenient Applies to both men and women Both objective and subjective Body weight (in kg) Body weight (in lb.)  703 or Height 2 (in meters) Height 2 (in inches) 27  Body Mass Index BMI Underweight: BMI