مقرر التغذية الصحية 2021/2022 PDF
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New Valley University
2021
Dr. Elham A. A. Abd El-Samad
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هذا مقرر في التغذية الصحية، مخصص لطلاب السنة الأولى في جامعة وادي النيل بمصر. يغطي المقرر أنواع الغذاء المختلفة ووظائفه، بالإضافة إلى عناصر التغذية، وطريقة حساب معدل الأيض الأساسي. يتميز المقرر بخطوات تنظيمية واضحة.
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Nutrition and Health Or Healthy nutrition Dr. Elham A. A. Abd El- Samad Healthy nutrition - Elham Introduction 019 FR * Course designation: 019FR * Course name: Healthy Nutrition * No. of credits: 2L-...
Nutrition and Health Or Healthy nutrition Dr. Elham A. A. Abd El- Samad Healthy nutrition - Elham Introduction 019 FR * Course designation: 019FR * Course name: Healthy Nutrition * No. of credits: 2L- -2 C * Prerequisites: - * Co-requisite course: * Course time: sunday: 10-12 * Instructor: Dr. Elham Abd-Elsabour * Office location: * Office hours: To be announced * Course description: To be attached * Question bank: Healthy nutrition To be attached - Elham Course objectives 019FR *At the end of the course the student is expected to have: 1- Be acquainted with the healthy feeding. 2- Consider community linked problems, ethics and traditions. 3- Be able to understand the close relationship between nutrition, dietary habits and quality of life, and also be able to identifyHealthy and unhealthy food consumption. 4- Examine the principles of meal planning, use of food groups and recommendations for nutrient intake and food componentsand nutritional directions. Healthy nutrition - Elham Course schedule Week/s Topic/s Week 1 Healty diet and our body Week 2 Components of healthy diet, Carbohydrate, Fats, Proteins, Mineral salts, Vitamins, Water and fibers. Week 3 Components of healthy diet, Carbohydrate, Fats, Proteins Mineral salts, Vitamins, Water and fibers Week 4 Healthy eating pyramid Week 5, 6 Physiology of the Human digestive system.- digestion, absorbtion metabolism and elimination. Week 7 First Term Exam Week 8-9 Feeding control and the factors that regulate the quantity of food intake especially Leptin and Gharelin. Week 10-11 How to read and penetrate nutrition facts. Week 12- Anabolic and catabolic hormones. 13 WeekHealthy Definition and calculations of basal metabolic rate (BMR). 14 nutrition - Elham Weighting of assessments Final-term exam 50% (W 16-17) Oral exam 10% (W 16-17) Mid-term exam 30 % (W 7) Practical exam --- Semester work 10% Healthy nutrition - Elham References -Introduction to Human Nutrition, Michale Gibney, Hester Vorster and Frans Kok, 2007 - kraues Food & Nutrition Therapy, Mahan, L. Kathleen and Escott-Stump, S. (2008) Saunders, Elsevier - Williams, M. H. (2007) Nutrition for Health, Fitness & sport Mc Graw Hill - angley-Evans, S., 2009. Nutrition- A Lifespan Approach, Wiley - – Blackwell, Chichester, U.K. Understanding Nutrition, Whitney and Rolfes, Wadsworth 2008 Healthy nutrition - Elham Healthy Nutrition for first level students 019 FR Lecture 1 Healthy diet and our body By Zoology Staff New Valley University – Egypt Healthy nutrition - Elham 2021/2022 What is Nutrition? -Nutrition: The study of how your body uses the food that you eat. -Nutrient: A chemical substance in food that helps maintain the body. Healthy nutrition - Elham Why do we eat? Satisfy physiological needs Habit SocialInfluences Psychological Influences Sensory Appeal Healthy nutrition - Elham What are our dietary needs? Meet basic physiological needs Body function Maintenance Temperature regulation Growth Physical activity Healthy nutrition - Elham Classification Of Foods Classification by origin: - Foods of animal origin - Foods of vegetable origin Classification by chemical composition: - Proteins – Fats – Carbohydrates – Vitamins – Minerals Healthy nutrition - Elham Classification by predominant function: Body building foods: meat, milk, poultry الدواجن, fish, eggs, pulses البقولetc Energy giving foods: cereals الحبوب, sugars, fats, oils etc. Protective foods: vegetables, fruits, milk, etc Healthy nutrition - Elham Food Components Fats, Proteins and Carbohydrates are sometimes called the “Macro components” They are required in large quantities and form the bulk of your food Minerals and vitamins are the “Micro components” They are required in small quantities (ranging from a few grams to a few milligrams/day) They are nevertheless essential to the proper functioning of the body Healthy nutrition - Elham Carbohydrates (Fuel and Building Material) Carbohydrates are a major source of energy in our diet and are used in the body as a store of available energy There are three main categories of carbohydrate A. Monosaccharides B. Oligosaccharides C. Polysaccharides Healthy nutrition - Elham A. Monosaccharides Monosaccharides are the basic building blocks of carbohydrates Two common monosaccharides are glucose and fructose (fruit sugar) Both have the formula C6H12O6 The difference between them is in their structural arrangement Healthy nutrition - Elham B. Oligosaccharides Oligosaccharides are carbohydrates formed from the combination of a few monosaccharide molecules Of these some disaccharides are common. Common examples include; Sucrose (glucose + fructose) Maltose (2 glucose) Lactose – milk sugar (glucose + galactose) Healthy nutrition - Elham C. Polysaccharides Polysaccharides comprise a very large number of monosaccharide units combined together Polysaccharides include Starch Glycogen Cellulose Starch is a energy source of plant origin, glycogen is the animal equivalent and is our main internal energy source Cellulose is a structural polymer found in many plants. Cellulose is a significant component of food, but is not digestible by humans. Healthy nutrition - Elham Proteins Proteins include the largest and most complex molecules known They are the main functional component of the body Proteins may be divided into two main categories Structural, e.g. muscle, connective tissue Functional, e.g. enzymes Proteins are built up from amino acids linked together by peptide bonds Healthy nutrition - Elham Functions of Proteins Body building Repair and maintenance of body tissues Maintenance of osmotic pressure Synthesis of bioactive substances and other vital molecules Healthy nutrition - Elham Lipids Lipids are a diverse group of biomolecules which share the property of being insoluble in water The main classes of lipids are Oils and fats (Saturated & Unsaturated) Phospholipds Steroids All except steroids are based on fatty acids. Healthy nutrition - Elham Fats (Composed of Lipids) Saturated Unsaturated Phospholipids Steroids Animal Fats Vegetable Fats Bi-layer of cell Sex Hormones membrane & Cholesterol Hydrogenation َهـد ََْرﭽـَــــــــة Healthy nutrition - Elham Functions of fats They are high energy foods, providing as much as 9 kcal for every gram. Fats serve as vehicles for fat-soluble vitamins. Fats in the body support viscera such as heart, kidney and intestine; and fat beneath the skin provides insulation against cold. Healthy nutrition - Elham Vitamins Low molecular weight organic substances. Required in small amounts in the diets of higher animals for normal growth, maintenance of health, and reproduction. They vary greatly in terms of their chemical nature and function 2 Types, Water-soluble and Fat-soluble. Requirements for vitamins differ during growth and maturity Additional; quantities required under special circumstance e.g. pregnancy Other factors – inheritance –Healthy microbial nutrition - Elham flora of the intestine - eating habits Healthy nutrition - Elham Vitamin A (and carotenoids) Functions: Food sources: Normal vision Liver Protects from Fish oil infections Eggs Regulates immune Fortified milk or other system foods Antioxidant Red, yellow, orange, (carotenoids) and dark green veggies (carotenoids) Healthy nutrition - Elham Vitamin D (the sunshine vitamin) Functions: Sources: Promotes absorption of Sunlight (10 – 15 mins calcium and phosphorus 2x a week) Helps deposit those in eggs bones/teeth Milk Regulates cell growth Orange juice Plays role in immunity Fortified cereals Healthy nutrition - Elham Vitamin E Functions: Sources: Antioxidant, may Vegetable oils lower risk for heart Foods made from oil disease and stroke, (salad dressing, some types of cancers margarine) Protects fatty acids and Nuts vitamin A Seeds Wheat, Green, leafy veggies Healthy nutrition - Elham Vitamin K Functions: Sources: Helps blood clot Body can produce on Helps body make its own (from bacteria some other proteins in intestines) Green, leafy veggies Some fruits, other veggies, and nuts Healthy nutrition - Elham Healthy nutrition - Elham Categories of minerals Major minerals Trace minerals Calcium Chromium Phosphorus Copper Magnesium Flouride Electrolytes (sodium, Iodine chloride, potassium) Iron Manganese Selenium Zinc Healthy nutrition - Elham Calcium Phosphorus Bone building Generates energy Muscle contraction Regulate energy metabolism Heart rate Component of bones, Nerve function teeth Helps blood clot Part of DNA, RNA (cell growth, repair) Almost all foods, especially protein-rich foods, contain phosphorus Healthy nutrition - Elham Magnesium Part of 300 enzymes (regulates body functions) Maintains cells in nerves, muscles Component of bones Best sources are legumes, nuts, and whole grains Healthy nutrition - Elham Electrolytes Chloride: Fluid balance Digestion of food, transmits nerve impulses Potassium Maintains blood pressure Nerve impulses and muscle contraction Sodium Fluid balance Muscles relax, transmit nerve impulses Regulates blood pressure Healthy nutrition - Elham Trace minerals Iodine: A mineral essential for the production of thyroid hormones. – sources: sea foods, iodized salt and foods containing iodized salt Iron: A mineral that is an essential constituent of blood and muscle and important for the transport of oxygen. Certain groups can be at risk of having low iron levels. These include young children and early teens, women with multiple pregnancies, and people with conditions that cause internal bleeding, such as ulcers or intestinal diseases. – sources: liver, red meat, egg yolk, legumes, whole or enriched grains and dark green vegetables. Manganese: A mineral that is important for growth, reproduction, formation of bone, and carbohydrate metabolism. – sources: whole grains, fruits, vegetables and tea. Selenium: A mineral associated with antioxidant properties and fat metabolism. It has been claimed to help prevent cancer and cardiovascular disease – sources: seafoods and organ meats. Zinc: A mineral involved in wound healing, taste sensation, growth and sexual maturation and part of many enzymes regulating metabolism – sources: meat, liver, eggs and seafood Healthy nutrition - Elham Water Body is 50-60% water Aids in fluid and electrolyte balance Transports molecules and cells throughout body Major component of blood Carries oxygen and nutrients to tissues Removes metabolic waste Healthy nutrition - Elham المحاضرة الثانية Healthy nutrition - Elham Macronutrient Digestion 1.Digestion at a Look 2. Mouth to the Stomach 3. Stomach 4. Small Intestine 4.1. Digestive Hormones, Accessory Organs, & Secretions 4.2. Carbohydrate Digestion in the Small Intestine 4.3. Protein Digestion in the Small Intestine 4.4. Lipid Digestion in the Small Intestine 5. Large Intestine Healthy nutrition - Elham 1. Digestion at a Look Digestion is the process of breaking down food to be absorbed or excreted. The gastrointestinal (GI) tract, the passage through which our food travels. A number of organs are involved in digestion, which collectively are referred to as the digestive system. The organs that form the gastrointestinal tract (mouth, esophagus, stomach, small intestine, large intestine, rectum, and anus) come into direct contact with the food or digestive content. Healthy nutrition - Elham Healthy nutrition - Elham 2. Mouth to the Stomach Digestion begins in the mouth, both mechanically and chemically. Mechanical digestion is called mastication المضغ, or the chewing and grinding طحنof food into smaller pieces. The salivary glands release saliva, mucus, and the enzymes, salivary amylase and lysozyme. Mouth with jaws, teeth Incisors (قواطعshearing), Canines األنياب (tearing )تمزيق, Premolars الطواحن األماميةand molars (grinding) and tongue. 2: 1: 2: 3 Dental formula :---------------- = 32 2: 1: 2: 3 Healthy nutrition - Elham Mechanical digestion using teeth and tongue. Healthy nutrition - Elham Swallowing Food will move down the pharynx where it reaches a "fork in the road", with the larynx as one road and the esophagus as the other. The esophagus road leads to the stomach; this is the direction that food should go. The other road, through the larynx, leads to the trachea and ultimately the lungs. Our body was designed in such a way that a small tissue, called the epiglottis, covers the opening to the trachea. It directs the food down the correct road as shown below. Healthy nutrition - Elham Figure: Cross section of face. The epiglottis covers larynx to prevent food and drink from entering the lungs Healthy nutrition - Elham Oesophagus Before being correctly guided into the oesophagus, the bolus البلعةof food will travel through the upper oesophageal sphincter. Sphincters العاصرةare circular muscles that are found throughout the gastrointestinal tract that essentially serve as gates between the different sections. Once in the oesophagus, wavelike muscular movements, known as peristalsis )التموج (موجات متعاقبة occur. Healthy nutrition - Elham At the end of the oesophagus the bolus will encounter the lower esophageal sphincter. This sphincter keeps the harmful acids of the stomach out of the oesophagus. However, in many people this sphincter is leaky, which allows stomach acid to reflux, or creep up, the oesophagus. The leaking of the very acidic gastric contents results in a burning sensation commonly referred to as "heartburn." If this occurs more than twice per week and is more severe, the person may have gastroesophageal reflux disease (GERD). Healthy nutrition - Elham Heartburn Healthy nutrition - Elham 3. Stomach After going through the lower esophageal sphincter, the food enters the stomach. Our stomach is involved in both chemical and mechanical digestion. Mechanical digestion occurs as the stomach churns( ( تحرك بعنفand grinds food into a semisolid substance called chyme (partially digested food). The lining of the stomach is made up of different layers of tissue. The mucosa is the outermost layer (closest to stomach cavity) as shown in the figure below. The mucosa is not a flat surface. Instead, its surface is lined by gastric pits. Healthy nutrition - Elham Healthy nutrition - Elham Table: Cells involved in the digestive processes in the stomach Type of Cell Function Neck Cells Secrete mucus Chief Cells Secrete pepsinogen & gastric lipase Parietal Cells Secrete HCl G Cells Secrete gastrin Healthy nutrition - Elham Healthy nutrition - Elham Healthy nutrition - Elham Table: Summary of chemical digestion in the stomach Chemical or Enzyme Action Stimulates chief cells to release Gastrin pepsinogen Stimulates parietal cells to release HCl. Denatures salivary amylase HCl Denatures proteins Activates pepsinogen to pepsin Pepsin Cleaves proteins to peptides Gastric lipase Cleaves sn-3 FA of triglycerides Healthy nutrition - Elham 4. Small intestine The small intestine is the primary site of digestion. It is divided into three sections: the duodenum األثنى عشر, jejunum الصائم, and ileum اللفائفى. After leaving the stomach, the first part of the small intestine that chyme will encounter is the duodenum. The organization of the small intestine is in such a way that it contains circular folds and fingerlike projections known as villi الخمالت. Healthy nutrition - Elham 4.1. Digestive Hormones, Accessory Organs, & Secretions Upon entering the duodenum, the chyme causes the release of two hormones from the small intestine: secretin and cholecystokinin (CCK, previously known as pancreozymin) in response to acid and fat, respectively. These hormones have multiple effects on different tissues. Healthy nutrition - Elham In the pancreas, secretin stimulates the secretion of bicarbonate (HCO3), while CCK stimulates the secretion of digestive enzymes. The bicarbonate and digestive enzymes released together are collectively known as pancreatic juice, which travels to the small intestine. In addition, CCK also stimulates the contraction of the gallbladder causing the secretion of bile into the duodenum. - The liver's major role in digestion is to produce bile. This is a greenish-yellow fluid that is composed primarily of bile acids, but also contains cholesterol, phospholipids, and the pigments bilirubin. Bile is then transported to the gallbladder. Healthy nutrition - Elham The gallbladder is a small, sac-like organ found just off the liver (see figures above). Its primary function is to store and concentrate bile made by the liver. The bile is then transported to the duodenum through the common bile duct. Secretin and CCK also control the production and secretion of bile. Secretin stimulates the flow of bile from the liver to the gallbladder. CCK stimulates the gallbladder to contract, causing bile to be secreted into the duodenum. Healthy nutrition - Elham 5. Large Intestine” The large intestine consists of the colon, the rectum, and the anus. The colon can be further divided into the cecum (a pouch connected to the junction of the small and large intestines), ascending colon, transverse colon, descending colon, and sigmoid colon as shown. The large intestine is responsible for absorbing remaining water and electrolytes (sodium, potassium, and chloride). It also forms and excretes Healthy nutrition - Elham feces. المحاضرة الثالثة Healthy nutrition - Elham Digestion and Absorption Before ingested food can be absorbed, therefore, it must be dissolved and broken down into small molecules. This dissolving and breaking-down process-digestion-is accomplished by the action of hydrochloric acid in the stomach, bile from the liver, and a variety of digestive enzymes that are released by the system’s exocrine glands. Each of these substances is released into the lumen of the GI tract by the process of secretion. Healthy nutrition - Elham The molecules produced by digestion then move from the lumen of the gastrointestinal tract across a layer of epithelial cells and enter the blood or lymph. This process is called absorption. Contractions of smooth muscles in the gastrointestinal tract wall serve two functions; they mix the luminal contents with the various secretions, and they move the contents through the tract from mouth to anus. These contractions are referred to as the motility of the gastrointestinal tract. Healthy nutrition - Elham Healthy nutrition - Elham Digestion and Absorption 1. Carbohydrates About two-thirds of carbohydrate is the plant polysaccharide starch, and most of the remainder consists of the disaccharides sucrose (table sugar) and lactose (milk sugar). Only small amounts of monosaccharides are normally present in the diet. Cellulose and certain other complex polysaccharides found in vegetable matter - referred to as fiber- cannot be broken down by the enzymes in the small intestine and are passed on to the large intestine, where they are partially metabolized by bacteria. Healthy nutrition - Elham Starch digestion by salivary amylase begins in the mouth and continues in the upper part of the stomach before the amylase is destroyed by gastric acid. Starch digestion is completed in the small intestine by pancreatic amylase. The products produced by both amylases are the disaccharide maltose and a mixture of short, branched chains of glucose molecules. These products, along with ingested sucrose and lactose, are broken down into monosaccharides -glucose, galactose, and fructose- by enzymes located on the luminal membranes of the small-intestine epithelial cells. Healthy nutrition - Elham 1. Lactase (β-galactosidase) which hydrolyses lactose into two molecules of glucose and galactose: Lactose Lactase Glucose + Galactose 2. Maltase (α-glucosidase), which hydrolyses maltose into two molecules of glucose: Maltose Maltase Glucose + Glucose 3. Sucrose (α-fructofuranosidase), which hydrolyses sucrose into two molecules of glucose and fructose: Sucrose Sucrose Glucose + Fructose Healthy nutrition - Elham These monosaccharides are then transported across the intestinal epithelium into the blood. Fructose enters the epithelial cells by facilitated diffusion, while glucose and galactose undergo secondary active transport coupled to sodium. These monosaccharides then leave the epithelial cells and enter the blood. Healthy nutrition - Elham Healthy nutrition - Elham Proteins Proteins are broken down to peptide fragments in the stomach by pepsin, and in the small intestine by trypsin and chymotrypsin, the major proteases secreted by the pancreas. These fragments are further digested to free amino acids by carboxypeptidase from the pancreas and aminopeptidase, located on the luminal membranes of the small- intestine epithelial cells. These last two enzymes split off amino acids from the carboxyl and amino ends of peptide chains, respectively. At least 20 different peptidases are located on the luminal membrane of the epithelial cells, with various specificities for the peptide bonds they attack. Healthy nutrition - Elham HCl in the stomach (pH 1–2) denatures dietary protein. Gastric secretions also include pepsinogen, which activated by acid produces the enzyme pepsin. Pepsin is stable and active at pH 1–2, it hydrolyzes some of the peptide bonds in the denatured proteins, which are broken down into smaller polypeptides. Healthy nutrition - Elham Healthy nutrition - Elham Next, the polypeptides enter the small intestine, where the pH is about 7–8. Proteases such as (trypsin, chymotrypsin, and carboxypeptidase) take over further hydrolysis of peptide bonds in the partially digested proteins. The combined action of the pancreatic proteases in the small intestine and other proteases in the cells of the intestinal lining frees the amino acids from dietary proteins. After active transport across cell membranes lining the intestine, the amino acids are absorbed directly into the bloodstream. Healthy nutrition - Elham المحاضرة الرابعة Healthy nutrition - Elham Malnutrition Healthy nutrition - Elham What is malnutrition? World Health Organization definition: The term is used to refer to a number of diseases, each with a specific cause related to one or more nutrients (for example, protein, iodine or iron) and each characterized by cellular imbalance between the supply of nutrients and energy on the one hand, and the body's demand for them to ensure growth, maintenance, and specific functions, on the other. Healthy nutrition - Elham Malnutrition includes: under nutrition and over nutrition. Under nutrition: is a consequence of consuming little energy and other essential nutrients or using or excreting them more. Over nutrition: an energy intake in excess of needs, resulting in overweight and obesity. Healthy nutrition - Elham On global scale the principal nutritional deficiency diseases are: 1. Kwashiorkor 2. Marasmus 3. Nutritional anemia 4. Iodine Deficiency 5. Iron Deficiency 6. Vitamin A 7. Vitamin D Healthy nutrition - Elham TYPES OF UNDERNUTRITION UNDERNUTRITION ACUTE CHRONIC UNDERNUTRITION UNDERNUTRITION Marasmus kwashiorkor Stunting Marasmic- Underweight kwashiorkor Wasting Healthy nutrition - Elham Healthy nutrition - Elham Protein – energy malnutrition 1- Marasmus Definition: It is a clinical syndrome and a form of under nutrition characterized by failure to gain weight due to inadequate caloric intake. Body weight is reduced to less than 60% of the normal (expected) body weight for the age Incidence: commonly in infants between the age of 6mo. - Healthy nutrition - Elham 2years (Infantile atrophy). Complications of Marasmus 1. Intercurrent infection : Broncho pneumonia. is the cause of death 2. Gastroenteritis 3. Hemorrhagic tendency الميل للنزيف 4. Hypothermia 5. Hypoglycemia 6. Edema (marasmic kwashiorkor ) نقص البروتين الهزالى Healthy nutrition - Elham 2-Kwashiorkor Definition It is a clinical syndrome and a form of malnutrition characterized by slow rate of growth due to deficient of protein intake, high CHO diet and vitamins & minerals deficiency (adequate supply of calories). Incidence Commonly in االطفال الصغارtoddlers between the age 1-3years, following or with weaning Healthy nutrition - Elham The extreme lack of protein causes an osmotic imbalance in the gastro-intestinal system causing swelling of the gut diagnosed as an edema or retention of water Extreme fluid retention observed in individuals suffering from kwashiorkor is a direct result of irregularities of the lymphatic system and capillary exchange. The lymphatic system serves three major purposes: fluid recovery, immunity, and lipid absorption. Victims of kwashiorkor commonly exhibit a reduced ability to recover fluids, immune system failure, and low lipid absorption, all of which result from severe undernourishment. Healthy nutrition - Elham Complication of kwashiorkor 1. Secondary infection ,fungal and bacterial infection 2. Hemorrhagic tendency 3. Gastroenteritis 4. Hypoglycemia 5. Hypothermia 6. Heart failure due to anemia and infection. Healthy nutrition - Elham 3-Iodine deficiency - thyroid Goiter: most commonly recognized consequence (enlarged thyroid) Occurs when thyroid gland is unable to meet the metabolic demands of the body through sufficient hormone production ,thyroid compensates by enlarging (works in short term) Healthy nutrition - Elham 4-Iron Deficiency Iron is critical for body: Carries oxygen to tissues from lungs Transports electrons within cells Integral part of important enzyme reactions Anemia is caused most commonly by iron deficiency (anemia is found in 40-60% of women and children in developing countries) Healthy nutrition - Elham 4- Vitamin A Deficiency Vitamin A –first fat-soluble vitamin recognized –beta carotene is its plant-derived precursor Plays roles in –vision , night blindness, xerophthalmia –immune defenses –maintenance of body linings &skin –bone and body growth –normal cell development –reproduction Healthy nutrition - Elham Other roles: Keeps mucous-forming cells from becoming keratinized Deficiency can result in poor health of many cells and reduced activity of some immune cells, such as T-lymphocytes Makes differentiation happen Stimulates osteoclasts-permits normal tooth spacing Healthy nutrition - Elham Vitamins A Deficiency Vit A (Retinol): night blindness, Xerophthalmia جفاف ) )الملتحمةand anaemia Xerostomia )(جفاف الفم Healthy nutrition - Elham Vitamin D Roles of Vit D –maintains blood calcium levels and therefore bone integrity,especially during growth –acts like a hormone in stimulating maturation of cells Deficiency -Rickets in children -Osteomaliciain adults Healthy nutrition - Elham Over nutrition Too many calories leading to obesity, diabetes, hypertension and cardiovascular disease On a global basis 79 % of all deaths attributable to chronic disease are already occurring in developing countries Healthy nutrition - Elham Obesity is a heterogeneous complex disorder of multiple etiologies characterized by excess body fat that threatens or affects socioeconomic, mental or physical health. Parental obesity: -If both parents are non-obese the child has only a 7% chance of developing obesity. -If one parents is obese the risk of develop obesity is increased to 40%. -If both parents are obese the risk for developing obesity double to 80%. Healthy nutrition - Elham Complications of Obesity: High blood pressure Diabetes. Stroke. Cancer. Heart attack. Arthritis Gall stones Thrombosis Healthy nutrition - Elham Secondary Malnutrition Condition that prevents proper digestion or absorption Often accompanies and exacerbates other types of malnutrition Causative conditions Loss of appetite Alteration of normal metabolism during infection/fever Prevention of nutrient absorption Diarrheal infection causing changes in GI epithelium Parasitic agents themselves Hookworms, tapeworms, schistosome worm, Malaria Healthy nutrition - Elham المحاضرة الخامسة Healthy nutrition - Elham Energy Balance and Body Composition Energy Balance Body weight is stable when energy consumed is equal to energy expended. When energy consumed is greater than expended, weight increases. When energy consumed is less than expended, weight decreases. Body composition Body composition is the proportion of muscle, bone, fat and other tissues that make up body weight. Achieving and maintaining a healthy weight is about managing energy balance and increasing the proportion of lean to fat tissue. Energy balance = energy in – energy out. Energy balance Energy in = calories consumed per day. Energy out = basal metabolic rate (BMR) + thermic effect of foods, + physical activity per day. Small increases in calories consumed per day or week can contribute to weight gain over time. Energy In: Food Intake; Regulated by – Appetite initiates eating through the sight, smell, thought or taste of food. – – Hunger is the feeling that motivates us to eat and is controlled by the hypothalamus. – Satiation is the feeling of satisfaction and fullness that causes us to stop eating. Satiety reminds us not to eat again until the body needs food. Food Intake – Dominant Hunger and Satiety Stress eating is eating in response to arousal. Thinking influences such as perceptions, memories, intellect, and social interactions – Sustaining Hunger and Satiety Protein is the most satiating. Complex carbohydrates are satiating. High-fat foods stimulate and induce people to eat more. Energy Out: Components of Energy Expenditure – Basal Metabolism (basal metabolic rate, BMR) Is the minimum calorific requirement needed to sustain life in a resting individual. It can be looked at as being the amount of energy (measured in calories) expended by the body to remain in bed asleep all day. Supports the basic processes of life Resting metabolic rate (RMR) is a measure of energy slightly higher than BMR. Components of Energy Expenditure – Basal Metabolism - Factors affecting BMR Aging slows BMR Height – the taller, the higher the BMR Growth increases BMR. Body composition (lean body mass increases BMR) Fever increases BMR. Stress increases BMR. Environmental temperature - both heat and cold raise BMR Components of Energy Expenditure – Basal Metabolism - Factors affecting BMR Fasting/starvation slows BMR. (Dieting) Malnutrition slows BMR. Hormones – Thyroid hormones can increase or decrease BMR. Smoking increases BMR. Caffeine increases BMR. Sleep slows BMR. Body Weight, Body Composition, and Health Body Fat and Its Distribution – Fat Distribution Intra-abdominal fat around abdominal organs may be critical. Central obesity is excess fat around the trunk of the body. It is also called abdominal fat or upper-body fat. Associated with increased risks Visceral Abdominal Fat Fat mainly around the waist is more likely to develop health problems than fat mainly in hips and thighs. This is true even if BMI falls within the normal range. Body Fat and Its Distribution – Waist Circumference Women with a waist measurement of more than 35 inches Men with a waist measurement of more than 40 inches Most Body Fat Is Stored in Adipose Tissue Two types of fat make up total body fat Essential fat - Found in bone marrow, heart, lungs, liver, spleen, kidneys, intestines, muscles, and central nervous system - Women have 4 times more essential fat than men Stored fat - Found in adipose tissue - Subcutaneous fat – located under the skin - Visceral fat – stored around the organs in the abdominal area Visceral and Subcutaneous Fat Storage in the Body Most Body Fat Is Stored in Adipose Tissue In negative energy balance, fatty acids are released from adipose cells Used as fuel and cells shrink In positive energy balance, fat accumulates and adipose cells expand Brown adipose tissue (BAT) is another type of fat tissue made up of specialized fat cells Contain more mitochondria and rich in blood Function is to generate heat Found primarily in infants White Adipocyte and Brown Adipocyte Body Mass Index Body mass index is a useful indicator of healthy weight for most people Body mass index (BMI) calculates body weight in relation to height BMI = body weight (in kilograms) / height2 (in meters) BMI = body weight (in pounds) × 703 / height2 (in inches) Healthy weight BMI 18.5–24.9 Overweight BMI 25–29.9 Obese BMI ≥ 30 Obese individuals have a 50–100% higher risk of dying prematurely than those at a healthy weight Health Risks Associated with Body Weight and Body Composition Being underweight increases health risks Symptomatic of malnutrition, substance abuse, or disease Higher risk of anemia, osteoporosis and bone fractures, heart irregularities, and amenorrhea Correlated with depression and anxiety, inability to fight infection, trouble regulating body temperature, decreased muscle strength, and risk of premature death May be unintentional and due to malabsorption associated with diseases such as cancer, inflammatory bowel disease, or celiac disease Being overweight increases health risks Overweight and obesity associated with increased risk of heart disease, hypertension, stroke, hyperlipidemia, gallstones, sleep apnea, and reproductive problems Increases risk of certain cancers including colon, breast, endometrial, and gallbladder cancer More than 80% of people with type 2 diabetes are overweight Metabolic syndrome is associated with central obesity المحاضرة السادسة Metabolism All chemical reactions occurring in the body – Includes synthesis and energy storage reactions (anabolism) – and energy liberating reactions (catabolism) – Anabolic reactions synthesize DNA and RNA, proteins, fats, and carbohydrates. Must occur constantly to replace molecules that are hydrolyzed in catabolic reactions Hormones & molecular signals that control metabolism Classic anabolic hormones include * Growth hormone * IGF1 and other insulin-like growth factors * Insulin * Testosterone * Estrogen Classic catabolic hormones include * Cortisol * Glucagon * Adrenaline and other catecholamines * Cytokines Hormonal Signals Regulate Feeding / Energy Expenditures CNS integrates sensory information with other information (smell, taste, psychological factors) to help regulate hunger and satiety, energy expenditures as well as growth and reproduction Hormonal Regulation of Metabolism Pancreatic Islets of Langerhans Contain 2 cell types involved in energy homeostasis: – α cells secrete glucagon when glucose levels are low By stimulating glycogenolysis in liver – β cells secrete insulin when glucose levels are high By promoting glucose uptake by tissues Normal fasting glucose level 65–105 mg/dl – Insulin and glucagon prevent levels from rising above 170mg/dl after meals – Or falling below 50mg/dl between meals Insulin It is secreted from the β cells of pancreas immediately following a meal and during periods of elevated blood sugar. It promotes the synthesis and storage of glucose as glycogen in the liver and muscles for short-term energy, and as fat for long-term energy. Brain uses 120 grams of glucose daily and the rest of body about 240 grams of glucose daily. Brain is only 2 % of body mass, but utilizes 50 % of the body’s energy to function optimally. So, brain absorbs glucose independently of insulin, which gives it first priority for bloodstream glucose over any other cells in the body. Glucagon Maintains blood glucose concentration above 50mg/dl. in liver Stimulates gluconeogenesis and lipolysis Secreted by the pancreas, its action increases the blood glucose level between meals by stimulating the breakdown of glycogen in the liver (glycogenolysis). It is the ratio between the hormones insulin and glucagon that determines whether there is storage or depletion of energy stores. Glucagon increases with aging after 25 and promotes elevated glucose levels. Catabolism During Fasting Increased glucagon secretion and decreased insulin secretion during fasting favors catabolism. Hormonal changes promote release of glucose, fatty acids, ketone bodies, and amino acids into blood Nutrients in diet Bloodstream Endogenous nutrient stores Eating: Nutrients in diet Bloodstream Uptake & storage of nutrients Insulin released Endogenous nutrient stores Fasting: Nutrients in Bloodstream Available for cells diet Glucagon + others Endogenous nutrient stores Thyroxine (T4) Thyroid secretes mostly tetraiodothyronine (thyroxine) and a little triiodothyronine (T3) in response to thyroid stimulating hormone (TSH) to: Stimulates the rate of cell respiration Necessary for growth and development, especially of the central nervous system (CNS) Increases metabolic heat (calorigenic effect) Essential for cold adaptation Hormones: Anabolic vs. Catabolic Build up Break down Protein synthesis Protein degradation Hypertrophy Atrophy Occurs more in type Occurs more in type II muscle fibers I muscle fibers 1. Testosterone In general, androgens promote protein synthesis and growth of those tissues with androgen receptors. Testosterone effects can be classified as virilizing and anabolic effects, although the distinction is somewhat artificial, as many of the effects can be considered both. Anabolic effects include growth of muscle mass and strength, increased bone density and strength, and stimulation of linear growth and bone maturation. Virilizing effects include maturation of the sex organs, particularly the penis and the formation of the scrotum in fetuses, and after birth (usually at puberty) a deepening of the voice, growth of the beard and auxiliary hair. Many of these fall into the category of male secondary sex characteristics. 2. Growth Hormone Secreted by anterior pituitary gland. Enhances cellular uptake of amino acids and protein synthesis. Has both direct and indirect effects on muscle Injections of GH stimulate muscle hypertrophy. – Stimulates bone and cartilage growth – Facilitates protein synthesis Increasing amino acid transport into muscle Stimulating RNA formation Facilitating protein synthesis – Exercise stimulates an increase in circulating GH and preserves plasma glucose for the CNS 3. Insulin-like Growth Factors (IGF-1) Polypeptide hormones secreted from the liver Mediate some effects of GH Stimulate protein synthesis 4. Cortisol Glucocorticoid from the adrenal cortex “Stress hormone” Converts amino acids to carbohydrates Increases proteolytic enzymes Inhibits protein synthesis Cortisol becomes a problem when its temporary job becomes permanent in chronic stress. In excess, it increases insulin levels and blood sugar levels, decreases immune functions, increases blood pressure and causes brain damage. 5. Catecholemines Epinephrine, norepinephrine, Increase force production in muscle Increase muscle contraction rate Increase blood pressure Increase blood flow Epinephrine (Anabolic) Epinephrine is a catecholamine that is secreted by the adrenal medulla and is important in strength and power activities. This hormone acts as the central motor stimulator, peripheral vascular dilator, and enhances enzyme system in muscle. Some of the physiological functions of epinephrine include: -increased muscle contraction rate -increased Blood Pressure -increased energy availability -increased blood flow Serotonin: Our appetite and behavior are influenced by the serotonin. It is also responsible for our peace of mind, quiet and comfort. Too much serotonin leads to nausea and diarrhea. Too little serotonin causes a person to be anxious, depressed, and aggressive. Serotonin needs to be balanced with melatonin. An imbalance increases stress, and can lead to depression and overeating. It is made in our brain from the amino acid tryptophan. Melatonin: Melatonin operates body’s “biological clock.” Melatonin production and release are governed mainly by cycles of light, dark and seasonal variations. It is turned “off” by daylight and turned “on” by darkness. It is strongest anticancer hormone. Production of melatonin decreases dramatically with age from about 25. It is produced by the pineal gland from serotonin. Dopamine: It is released just before we awake, but if we go to sleep too late in the dark cycle, it will not be released. It controls the “fight or flight” mechanism by controlling the release of adrenaline, which us in emergency. It is also responsible for involuntary movements such as emotional drive. Dopamine also declines with age. Full-blown dopamine deficiency is known as Parkinson’s disease. Dopamine is degraded in the brain by the enzyme monoamine oxidase, which increases progressively in activity from about the age of 30. It appears to be responsible for many of the physical and mental symptoms of aging. Anabolic-Androgenic Steroids (AAS) Side Effects: Mild – increased acne, body hair and aggressive behavior. Prolonged use interferes with ability to naturally produce testosterone in the face of withdrawal. Common problems due to chronic abuse include: hypertension, atherosclerosis, tendon damage, reduced fertility in males, heart attacks and liver cancer. المحاضرة السابعة Food additives Learning objectives To identify the reason(s) why food additives are used. To understand the different sources of food additives. To understand the different roles and functions of food additives in food. What are food additives? Food additives are substances added to products to perform specific functions. These functions include preserving, i.e. increasing shelf-life or inhibiting the growth of pathogens, or adding colouring and flavouring to food for interest and variety. Types of additives Additives may be: natural – found naturally, such as extracts from beetroot juice (E162), used as a colouring agent; manmade versions – synthetic identical copies of substances found naturally, such as benzoic acid (E210), used as a preservative; artificial – produced synthetically and not found naturally, such as nisin (E234), used as a preservative in some dairy products and in semolina and tapioca puddings. 1. Preservatives Preservatives aim to: prevent the growth of micro-organisms which could cause food spoilage which lead to food poisoning; extend the shelf-life of products, so that they can be distributed and sold to the consumer with a longer shelf-life. For example, bacon, ham, corned beef and other ‘cured’ meats are often treated with nitrite and nitrate (E249 to E252) during the curing process. Sodium Nitrite & Sodium Nitrate Sodium nitrite and nitrate are used as an additive in meats and fish because it is a preservative, it adds color, and prevents from bacterial spoilage. Recent studies have suggested that high consumption of cured meats such as bacon, sausage, and luncheon meats may be linked to colon cancer. 2. Antioxidants Antioxidants aim to: prevent food containing fat or oil from going rancid due to oxidation, i.e. developing an unpleasant odour or flavour. prevent the browning of cut fruit, vegetables and fruit juices (and so increase shelf life and appearance). For example, vitamin C, also known as ascorbic acid, or E300, is one of the most widely used antioxidants. i) Primary antioxidants Terminate free radical chains and function as electron donors.They include the phenolic antioxidants, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) ii) Oxygen scavengers Can remove oxygen in a closed system Most widely used compounds are Vit C, and related substances, ascorbyl palmitate. iii) Chelating agents or sequestrants(can prevent the oxidation of the fats in the food)- They remove metallic ions, especially copper and iron, that are powerfull pro-oxidants. Citric acid is widely used for this purpose Amino acids and ethylene diamine tetraacetic acid (EDTA) are examples of chelating agents((مزيلة للمعادن الثقيلة من الدم iv) Enzymatic antioxidants Can remove dissolved head space oxygen, such as glucose oxidase Superoxide dismutase can be used to remove highly oxidative compounds from food systems v) Natural antioxidants Present in many spices and herbs Rosemary and sage نبات المرمريةare the most potent antioxidant spices 3. Colours Colours aim to: restore colour lost during processing or storage, e.g. marrowfat peas; ensure that each batch produced is identical in appearance or does not appear ‘off’; reinforces colour already in foods, e.g. enhance the yellowness of a custard; give colour to foods which otherwise would be colourless (e.g. soft drinks) and so make them more attractive. 4. Flavour enhancers Flavour enhancers bring out the flavour in foods without imparting a flavour of their own, e.g. monosodium glutamate (E612) is added to processed foods. For example some soups, sauces and sausages. Flavourings, on the other hand, are added to a wide range of foods, usually in small amounts to give a particular taste. These do not have E numbers because they are controlled by different food laws. Ingredients lists will say if flavourings have been used, but individual flavourings might not be named. 5. Sweeteners Sweeteners include: Intense sweeteners, e.g. saccharin, have a sweetness many times that of sugar and therefore are used in small amounts, e.g. in diet foods, soft drinks, sweetening tablets. Bulk sweeteners, e.g. sorbitol, have a similar sweetness to sugar and are used at similar levels. If concentrated drinks that contain sweeteners are given to children between the ages of 6 months to 4 years, it is important to dilute them more than for adults. Infants under 6 months should not be given these drinks. 6. Acids, bases and buffers Acids, bases and buffers control the acidity or alkalinity of food, for safety and stability of flavour. 7. Anti-caking agents Anti-caking agents ensure free movement or flow of particles, e.g. in dried milk or table salt. 8. Anti – foaming agents Anti-foaming agents prevent or disperse frothing, e.g. in the production of fruit juices. 9. Emulsifiers, stabilisers, gelling agents and thickeners Emulsifiers help mix ingredients together that would normally separate, e.g. Lecithins (E322). Stabilisers prevent ingredients from separating again, e.g. locust bean gum (E410). Gelling agents are used to change the consistency of a food, e.g. pectin (E440), which is used to make jam. Thickeners help give food body, e.g. can be found in most sauces. Regulation of food additives When evaluating the safety of food additives, the following criteria are examined by the Food and Drug Administration : 1) the composition and properties of the substance. 2) the amount that would typically be consumed. 3) immediate and long-term health effects. After all the criteria are investigated, the FDA makes their judgment based on the scientific evidence that is available to determine that the additive will cause no negative side-affects. Legislation in World Type of Additive E Number Colouring Most begin with 1 Preservatives Most begin with 2 Flavourings Not numbered Antioxidants E300 – 321 Emulsifiers and stabilizers E322 and some numbers between E400 and E495 Sweeteners Most begin with 4 or 6 E-numbers (food labels) المحاضرة الثامنة Weight Management Strategies Treatment of obesity Treatment of obesity depends on decreasing energy input below energy expenditure and creating a sustained negative energy balance until the desired weight loss is achieved. In other words, this means either reducing energy intake or increasing energy expenditure What is the Goal of Obesity Treatment? Specifically, the goal of obesity treatment should be refocused from weight loss alone, which is often aimed at appearance, to weight management, achieving the best weight possible in the context of overall health. Who Should Consider A Weight Management Intervention? Persons with a BMI of >30 Persons with a BMI between 25-29.9 OR a high-risk waist circumference, and two or more risk factors Persons who are ready to change Obesity-Associated Risk Factors: High Absolute Risk Established coronary heart disease Other atherosclerotic diseases Type 2 diabetes Sleep apnea Obesity-Associated Risk Factors: 3 or More = ↑ Risk Hypertension Cigarette smoking High low-density lipoprotein cholesterol Low high-density lipoprotein cholesterol Impaired fasting glucose Family history of early cardiovascular disease Age (male ≥ 45 years, female ≥ 55 years) Treatment Modalities Diet – (proper “Healthy” nutrition) Behavior therapy/modification/change Pharmacotherapy Physical Activity Surgery 1.Weight Loss Diets Is the most widely-prescribed method of weight reduction Should be nutritionally adequate except for energy Energy level varies with individual’s size, sex, and activity, ranging from 800 kcals to 1500 kcals Should be relatively high in carbohydrate (50-55% of total kcals) CHO sources should be fruits, vegetables, whole grains Include generous protein (15-25% of kcals) for increased satiety and to assure adequate supply Fat < 30% of kcals Increased fiber to improve satiety Alcohol and high-sugar foods should be limited to limit excess energy. Use of non-nutritive sweeteners and fat replacements may improve the palatability of the diet. Vitamins and mineral supplements may be needed in programs that provide