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Objectives: • To define nutrition and related words. • To identify nutritional requirements. • To understand Food pyramid. • To list types of nutrients and relation to health. • To define malnutrition and its classification. • To list main malnutrition problems. • To describe Obesity. • Nutrition is defined as the science of food and its relationship to health. Or, • The process of making use of food. • It is concerned primarily with the part played by nutrients in body growth, development and maintenance . • Dietetics is the practical application of the principles of nutrition; it includes the planning of meals for the well and the sick. • Good nutrition means “maintaining a nutritional status that enables us to grow well and enjoy good health.” • Nutrients are substances (specific dietary constituents) that are crucial for human life, growth & well-being. • Macronutrients (carbohydrates, lipids, proteins & water) are needed for energy and cell multiplication & repair. • Micronutrients are trace elements & vitamins, which are essential for metabolic processes. CLASSIFICATION OF FOODS • Classification by origin: - Foods of animal origin - Foods of vegetable origin • Classification by chemical composition: - Proteins – – – – Fats Carbohydrates Vitamins Minerals CLASSIFICATION BY PREDOMINANT FUNCTION • Body building foods: • -meat, milk, poultry, fish, eggs, pulses etc • Energy giving foods: • -cereals, sugars, fats, oils etc. • Protective foods: • -vegetables, fruits, milk, etc • Community Nutrition: Identification of nutritional needs of population groups and available resources. • Nutritional Epidemiology: It is the investigation of the relationship between diet and disease. Nutritional requirements Recommended Dietary Allowances (RDA): The level of nutrients considered to be adequate to meet the nutritional needs of all healthy persons. Knowledge of RDA is necessary to: • Assess the nutritional adequacy of diets for growth of infants, children and adolescents. • Maintain health in adults of both sexes and during pregnancy and lactation. The adequate diet & Food Pyramids Food Group System: • Classifies food according to similarity in nutrient content. • Foods placed in each group have a high nutrient density. Daily Food guide with Nutrient Pattern and Recommended Quantity. Group Milk and Cheese Key Nutrients Calcium, Protein Phosphorus, riboflavin Meats, poultry, fish, beans Protein, Iron Niacin, Thiamin Red meat -> Zinc Egg yolk and liver -> Vitamin A Dry beans and Nuts -> Magnesium Quantity Comments 3 cups for children 4 cups for teenagers 2 cups for adults Low-fat milk products have generally all the same nutrient content, however they are lower in calories and vitamin A. 2 servings Serving size: 2-3 ounces 1 ounce of meat = 1 egg or ½ cup cooked beans 1 ounce = 30 gm Legumes and nuts has a lower biological value than meat. They can be combined with animal or grain products to increase protein quality. Cholesterol and vitamin B12 are found only in animal sources. Vegetable and fruits Vitamin A 4 servings Vitamin C Serving size: ½ Cup vegetable or fruit Carbohydrate (fiber) 1 Medium fruit Bread and Cereal Fats and sweets Carbohydrate 4 servings Thiamin Serving size: Niacin 1 slice bread Iron ½ cup rice Fats Fats should not be more than 35% of the total calories with 10% from polyunsaturated fats. Sugars should not be more than 10% of the calorie intake. Carbohydrate Calories Include one good vitamin C source daily, include deep yellow or dark green vegetable frequently, include unpeeled fruits and vegetables for fiber. During processing, some essential nutrients are lost. Less refined products are recommended Unenriched, refined bakery products are included here because they provide low levels of nutrients compared to calories Food Pyramid Lessons from Food Pyramid: 1. Maintain a healthy weight. Studies show that the healthiest range for body weight is when the body mass index (BMI) is about 17 to 22. 2. Eat good fats and avoid bad fats. • • • • • Good fats are the oils found in nuts, seeds, grains and fish. They are high in the unsaturated fats necessary for good health. Good fats should contribute 30 to 45% of the total fat. Avoid saturated fats (animal fats and tropical oils e.g. coconut) to minimize the risk of heart disease. Trans-saturated fats are mainly found in margarines and commercial baked foods. 3. Eat whole-grain carbohydrates. Why? • whole-grain are more nutritious than refined carbohydrates • Being more slowly digested • Place less stress on pancreatic insulin production. • Sources of whole grain carbohydrates include whole meal bread, whole wheat, brown rice. • Avoid white bread, baked goods and pasta made with white flour. 4. Avoid red meat as a protein source and emphasize plant proteins. • Red meat consumption is linked to a variety of chronic diseases & increases the risk of hip fracture. • Animal proteins are usually packaged with saturated fat. 5. Eat plenty of vegetables and fruits. • Potatoes are not included as a vegetable. • Dark green leafy vegetables, and fruit are clearly beneficial. • A diet high in fruits and vegetables lowers blood pressure and cholesterol and reduces the risk of cancer. 6. Take a multivitamin daily. • This recommendation is insurance against any inadvertent deficiencies. Mediterranean Pyramid Main types of Nutrients Energy Supplying Nutrients: • Protein • Lipids • Carbohydrates Non-Energy Supplying Nutrients: • Vitamins • Minerals • Water PROTEINS • Proteins are complex organic nitrogenous compounds. • They also contain sulfur and in some cases phosphorous and iron. • Proteins are made of monomers called amino acids. • There are about 20 different aminoacids which are found in human body. • Of this 8-9 aa are termed “essential” as they are not synthesized in human body and must be obtained from dietary proteins. Protein Needs: • Adults: 0.8 gm/kg body weight per day • Excess protein is not used to build more muscle – If the body needs energy, the extra amino acids are used for energy – If the body does not need energy, the extra amino acids can be converted to fat and stored. Sources: • Complete proteins have all essential amino acids (animal sources) • Incomplete proteins lack one or more essential amino acids (plant sources) Functions of Proteins • Body building • Repair and maintenance of body tissues • Maintenance of osmotic pressure • Synthesis of bioactive substances and other vital molecules e.g. immunoglobulins Lipids • • Lipids include cholesterol and triglycerides Fat is necessary for health Functions 1. Main source of energy (9Kcal/g). 2. Spare protein. 3. Adipose tissue holds the body organs and nerves in place. 4. Maintain body temperature. 5. Transportation of fat soluble vitamins. Classification • Saturated fat: – Animal foods generally are rich sources – Palm and coconut oil also are rich sources • Monounsaturated fat – Olives, peanuts, and canola oil are rich sources • Polyunsaturated fat – Corn, sunflower, cotton seed, and nut oils are rich sources • Hydrogenated fat Hydrogenated fat • Hydrogenation process hardens liquid oils into more solid margarine. – It makes unsaturated fat in oil more saturated – Also it produces an unhealthy type of fat called “trans fatty acid” • Saturated fat and trans fatty acids may be harmful to health • Baked products and fried foods are often made with hydrogenated fats Cholesterol • Cholesterol is necessary for cell membranes and the production of vitamin D, bile, and certain hormones • It is found only in animal foods • High blood cholesterol levels are associated with increased risk of heart disease Fats yield fatty acids and glycerol on hydrolysis • Fatty acid content of different fats ( in per cent) • • • • • • • • • • Fats Saturated Monounsaturated Polyunsaturated fatty acids fatty acids fatty acids Coconut oil Palm oil Cotton seed oil Groundnut oil Sunflower oil Corn oil Soya bean oil Butter 92 46 25 19 8 8 14 60 6 44 25 50 27 27 24 37 2 10 50 31 65 65 62 3 Fat requirements • The WHO Expert committee on Prevention of Coronary Heart Disease has recommended only 20 to 30 per cent of total dietary energy to be provided by fats. (<30%) • At least 50 per cent of fat intake should consist of vegetable oils rich in essential fatty acids. Carbohydrates Functions: 1. Carbohydrate is the main source of energy, providing 4 Kcals per one gram 2. Carbohydrate is essential for the synthesis of certain non-essential amino acids. 3. Necessary for normal fat metabolism. 4. Necessary for integrity of nerve cells. 5. Lactose allow growth of beneficial bacteria in the intestine. 6. Important for normal elimination (excretion); fibers Recommended carbohydrate intake is 55% to 65% of calories, primarily from starchy foods Classification of Carbohydrates 1. 2. 3. 4. Monosaccharides: glucose &fractose Disaccharides: Sucrose (G + F) Oligosaccharides (3-10). Polysaccharides (11-1000) a-Indigestable e.g. cellulose b-partially digestable e.g.raffinose c-Digestable e.g. starch The inability of the body to metabolize carbohydrates properly =DM Fiber • Indigestible plant material e.g. cellulose • Dietary fiber is mainly non-starch polysaccharide • It is found in vegetables, fruits and grains. • Soluble fiber swells or dissolves in water – Rich sources include apples, bananas, citrus fruits, carrots • Importance: – Reduces cholesterol absorption – Slows absorption of glucose Fiber • Insoluble fiber remains unchanged in water – Rich food sources include brown rice, wheat bran, and whole grain products • Importance: • High fiber diet reduces the risk of heart disease, diabetes type II, diverticulosis, hemorrhoids, constipation, and possibly colorectal cancer * Refined foods lose fiber-rich parts during processing Non-Energy Supplying Nutrients • Vitamins • Minerals • Water Vitamins • Regulate growth, • maintain tissues, and • help carbohydrates, proteins, and fats release energy • Provide no calories (energy) • Needed in very small amounts Classes of Vitamins • Water Soluble: 8 different B vitamins and vitamin C • Fat Soluble: Vitamins A, D, E, and K • Most healthy people do not need supplements; vitamins can be obtained by eating a variety of foods – Supplementation can increase the risk of consuming toxic high levels Fat soluble vitamins Vitamin A • «Vitamin A» covers both: – a pre-formed vitamin, retinol, and – a pro-vitamin, beta carotene, which is converted to retinol in the intestinal mucosa. Sources: – Retinol in liver, code liver oil & eggs (animal sources) – Beta carotene: Coloured plants e.g. carrot, mango, apricot, pumpkin,….. (plant sources) VITAMIN Sources: • liver • milk • eggs • spinach • carrots • tomatoes • butter A Functions of Vitamin A • It is essential for normal vision. • It is necessary for maintaining the integrity and the normal functioning of glandular and epithelial tissue which lines intestinal, respiratory and urinary tracts as well as the skin and eyes. • It supports growth, especially skeletal growth • It may protect against some epithelial cancers such as bronchial cancers. Vitamin D • The nutritionally important forms of Vitamin D in man are: – Calciferol (Vitamin D2) and – Cholecalciferol (Vitamin D3) Sources: • liver • caviar • Butter • Eggs • Ultraviolet rays Functions of vitamin D • Intestine: Promotes intestinal absorption of calcium and phosphorus • Bone: Stimulates normal mineralization, Enhances bone reabsorption, Affects collagen maturation • Kidney: Increases tubular reabsorption of phosphate Deficiency of vitamin D Deficiency of vitamin D leads to: • Rickets in children • Osteomalacia in adults Vitamin E • Antioxidant- Protects RBCs from haemolysis. • Present in wheat germ and green leafy vegetables Vitamin K • Important for blood coagulation • Present in leaves of plants + natural (flora). • Deficiency causes haemorrhagic manifestations. VITAMIN contains in: • liver • corn • eggs • vegetable oils E Water soluble vitamins Thiamine (B1) • Function: essential for the utilization of carbohydrates. • Present in brewer yeast, beans and legumes. • Deficiency: Beri-beri Deficiency of thiamine • Beriberi may occur in three main forms: – peripheral neuritis, – cardiac beriberi, – infantile beriberi, signs of peripheral neuropathy. Riboflavin (B2) • Important for cellular metabolism, oxidation and reduction. • Present in milk, liver, meat, eggs, fish and vegetables. • Deficiency: angular stomatitis &magenta tongue. VITAMIN B6 • Pyridoxine (vitamin B6) plays an important role in the metabolism of amino acids, fats and carbohydrate. • The requirement of adults vary directly with protein intake. VITAMIN B12 • Vitamin B12 is a complex organo-metallic compound with a cobalt atom (Cyanocobalamine) • Vitamin B 12 cooperates with folate in the synthesis of DNA. • Vitamin B 12 has a separate biochemical role, unrelated to folate, in synthesis of fatty acids in myelin. Vitamin B12 deficiency • Vitamin B12 deficiency is associated with megaloblastic anaemia (pernicous anaemia), demyelinating neurological lesions in the spinal cord and infertility (in animal species). • Dietary deficiency of B12 may affect subjects who are strict vegetarians and eat no animal product. Nicotinic acid • Important for nervous system and epithelium. • Present in yeast, liver, peanut, meat and intestinal flora. • Deficiency: – Pellagra: • Dermatitis • Dementia • Diarrhoea VITAMINS OF GROUP Sources: • liver • kidneys • legumes • curds • cheese • fish • bread B VITAMIN C • Vitamin C (ascorbic acid) is a water-soluble vitamin. • It is the most sensitive of all vitamins to heat. • Vitamin C has an important role to play in tissue oxidation • It is needed for the formation of collagen of connective tissue, which accounts for 25% per cent of total body protein. • Present in vegetables and fruits. Deficiency of vitamin C • Deficiency of vitamin C results in scurvy. • Signs of scurvy are: – Swollen and bleeding gums, – Subcutaneous bruising, – Bleeding into the skin or joints, – Delayed wound healing, – Anaemia and weakness. Minerals • Minerals are certain elements that may: – regulate chemical reactions in the body – be part of organic molecules • Iron in hemoglobin • Calcium in bone and teeth • Small amounts are needed for health Calcium • Most plentiful mineral in the body – Needed for strong bones and teeth – Involved in regulating blood pressure, clotting blood, and muscular movements • Bones store calcium – Osteoporosis • Bones lose mineral density and strength • Aging people, especially menopausal women, are at risk Calcium contains in: • milk, • cottage cheese, • cheese, • yoghurt, • parsley. Iron • Most of the body’s iron is in hemoglobin, which is in red blood cells – The iron in hemoglobin picks up oxygen in the lungs and transports it to cells • Iron deficiency is one of the most common nutritional disorders worldwide Iron Sources: • liver • red meat, • apples, • dried fruit • molasses. Water • Variety of functions: – helps transport of materials in the body, and – involved in many chemical reactions. • Beverages and most foods, especially fruits and vegetables, supply water • Diuretics such as alcohol and caffeine increase losses of water from body Water • To be properly hydrated, a person needs at least 8 cups of water daily • Dehydration can be deadly • Sports drinks replenish minerals and water that are lost during heavy exercise Malnutrition Definition: Malnutrition is a pathological state resulting from a relative or absolute deficiency or excess of one or more essential nutrients. The major forms of malnutrition are: Under-nutrition: It is a pathological state resulting when nutrient intake does not regularly meet the nutrient needs for cell activities and body maintenance. It includes: 1. Macronutrient deficiency e.g., protein-energy malnutrition (marasmus &kwashiorkor). 2. Micronutrient deficiency e.g. iron deficiency anaemia, vitamin A deficiency, Iodine deficiency….etc. The major malnutrition problems in the world are: 1. Protein–energy malnutrition (PEM) 2. Iron deficiency anaemia 3. Iodine deficiency disorders (IDD) 4. Vitamin A deficiency (VAD) Iron deficiency • Over 2 billion people suffer from some form of iron deficiency • Anaemia linked to iron and/or folic acid deficiency is among the world’s major nutritional disorders • Africa & South Asia have the highest overall incidence of anaemia, followed by Latin America & East Asia • Parasitic infestation contributes to high percent of cases in developing countries. Consequences of iron deficiency • Reduces work capacity, thus productivity, earnings • Associated with 50% of maternal deaths • Retards fetal growth, causes low birth weight (LBW) & increases infant mortality • Impairs ability to resist disease; in childhood, reduces learning Improving Iron status • Iron tablets • Iron fortification of basic foods (bread) • Increased consumption of iron rich foods & factors which enhance absorption • Control of parasitic infections Iodine deficiency disorders (IDD) • In 1990: 1.6 billion people worldwide at risk of IDD • At least 655 million with goitre • 43 million with some degree of mental impairment • 11 million with cretinism • Moderate Iodine deficiency is associated with average reduction of over 13 IQ points Prevention of IDD • Adequate intake of Iodine can prevent all IDD • make milder forms of goiter disappear • improve development of older children mildly affected • Severe forms of IDD such as cretinism, cannot be reversed; But, • can only be prevented by adequate intake of Iodine during pregnancy • Now, iodizing salt is all over the world Vitamin A deficiency (VAD) • May be subclinical, severe or moderate • Clinical (xerophtalmia) – 2.8 million children 0-4 years old • Blindness, total or partial – at least half a million children a year – about half die within a few months Deficiency of vitamin A The signs of vitamin A deficiency are: • Follicular hyperkeratosis, • Night blindness • Conjunctival xerosis • Bitot's spots • Corneal xerosis • Keratomalacia Improving vitamin A status • Increased intake of vitamin A rich foods e.g. eggs, butter, whole milk, liver, red palm oil, dark green, yellow & red fruits & vegetables • Fortification of basic foods with vitamin A • Supplements e.g. 2 capsules of Vitamin A per year to young children Over-nutrition: It is a pathologic state resulting when nutritional intake exceeds the body needs, which leads to caloric excess over an extended period of time. Definition Obesity is Disorder of Body Regulatory Systems leads to Excess Body Fat Assessment: Body Mass Index (BMI) Waist Circumference (WC) Waist to Hip ratio (WHR) Causes & Associated Factors •Genetic: Complex Polygenic •Environmental and Behavioral •Signaling factors: • Hormonal • Neurologic • Psycological Assessment of Obesity • The international standard for assessing body size in adults is the body mass index (BMI). • BMI is computed using the following formula: BMI = Weight (kg)/ Height (m²) • Evidence shows that high BMI (obesity level) is associated with type 2 diabetes & high risk of cardiovascular morbidity & mortality BMI (WHO - Classification) BMI < 18.5 = Under Weight BMI 18.5-24.5= Healthy weight range BMI 25-30 = Overweight (grade 1 obesity) BMI >30-40 = Obese (grade 2 obesity) BMI >40 =Very obese (morbid or grade 3 obesity) Waist circumference Waist circumference predicts mortality better than any other anthropometric measurement. It has been proposed that waist measurement alone can be used to assess obesity, and two levels of risk have been identified MALES FEMALE LEVEL 1 LEVEL2 > 94cm > 102cm > > 80cm 88cm Waist circumference Level 1 is the maximum acceptable waist circumference irrespective of the adult age and there should be no further weight gain. Level 2 denotes obesity and requires weight management to reduce the risk of type 2 diabetes & CVS complications. Waist Hip Ratio (WHR) • Visceral obesity (apple shaped) • Peripheral obesity (Pear shaped) WHR > 0.8 F > 1.0 M Visceral Vs Peripheral WHR < 0.8 F < 1.0 M Interpretation of WHR High risk Females: WHR= >0.80 or >80% Males: WHR= >0.95 or >95% It indicates central (upper body) or visceral obesity and is considered high risk for diabetes & CVS disorders. • A WHR below these cut-off levels is considered low risk (peripheral obesity).