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Food Sciences and Nutrition 112 Principals of Human Nutrition Food and Nutrition: An Introduction From birth to death food is a dominant factor in our life. Besides providing the energy for breathing at night and full activity during daytime, food builds, maintains, and regulates muscles and bones, nerves and brain, eyes, hair, and all our physical being. Food is also used as a link in our friendship, and as a symbol of our religious life. Through the ages, people have learned that some foods are more nourishing than others. The science of nutrition, on the other hand, was grown only after the development of the sciences of chemistry and physiology and had its beginning in the late eighteen century. Thereafter, since 1900, the functions of the nutrients in the body, the nutritive values of foods, the body requirements for nutrients, and the role of nutrition in health and disease were studied. It should be emphasized that much still remains to be learned. 1 Commonly used terms in nutrition Nutrition: The sum of processes involved in taking in food and using them for growth, development, and the maintenance of health. It includes eating the correct kind and amount of food, digestion, and absorption of the nutrients for the maintenance of body tissue, production of energy, and elimination of wastes. Nutritional science: The body of knowledge developed through controlled research that relates to the process involved in nutrition. It includes managing food requirements of humans for maintenance, growth, activity, reproduction, and lactation. Nutrients: Any chemical substance found in food that is used to promote body functions. They are divided into six basic groups: carbohydrates, fats, proteins, vitamins, minerals, and water. Nutrient requirement: A Specific amount of a specific nutrient needed by the body at a certain age. Essential Nutrients: Nutrients that are necessary for life and can’t be synthesized by the body and therefore, must be included in the diet. Food: Any substance, usually of plant or animal origin, when eaten, digested, and absorbed provides one or more of the nutrients. Diet: Includes the kinds and amounts of food and drink consumed each day. It includes both the normal and the therapeutic diet. 2 Balanced Diet: A diet that provides all the essential nutrients in appropriate amounts. Nutritional Status: The physical condition of the individuals that can be determined by their diet. Nutritional Assessment: The measurement of nutritional status based on anthropometric and biochemical data and dietary history. Health: The state of complete physical, mental, and social well-being and not merely the absence of disease. Malnutrition: Any disorder concerning nutrition. It may result from an unbalanced, insufficient, or excessive diet. It includes: Overnutrition: The condition that results from excessive caloric intake and/or one or more nutrients. Undernutrition: The condition that results from an insufficient caloric intake and/or one or more nutrient. Recommended Dietary Allowance (RDA): The average daily nutrient intake level that is sufficient to meet the nutrient requirements of nearly all (97-98%) healthy individuals in a particular life stage and gender group. Energy: The capacity to do work. Food provides the body with energy or fuel it needs to stay alive, move, and grow. The chemical energy found in food and used by the body is measured in kilocalorie (Kcal) or calorie (cal). Energy Yielding Nutrients: Nutrients that the body can use for energy production (carbohydrate, fat, and protein). 3 Calories: Units of energy. It is the amount of heat required to raise the temperature of a kilogram of water one-degree Celsius. Metabolism: The sum of all chemical changes that take place in the body by which it maintains itself and produces energy for its functioning. Metabolism is of two types: Anabolism: The synthesis of complex molecules from simpler ones. The reaction is energy dependent (e.g: growth). Catabolism: The break down of complex molecules to simpler ones, which leads to the release of energy (e.g: starvation, illness). 4 Tools for Choosing a Healthy Diet Understanding Food Labels Ingredient List: The ingredient list includes all of the substances added when preparing a food, including food additives, colors, and flavoring. The ingredients are listed in order of their prominence by weight. Nutrition Facts: Lists the serving size of the food followed by the total calories, calories from fat, total fat, saturated fat, cholesterol, sodium, total carbohydrate, dietary fiber, sugars, and protein per serving of the food. Illustration: 5 The Food Guide pyramid: In June 2011, MyPlate replaced MyPyramid. A website — ChooseMyPlate.gov — which contains resources and tools for more specific information about what and how much to eat. On this website, consumers will find specific recommendations for each USDA Food Group, based on the 2010 Dietary Guidelines for Americans (DGA), including proportions based on research that relate to individual calorie and nutrient needs. The new MyPlate icon is a plate split into four sections, each representing a different type of food (protein, whole grains, fruits and vegetables). The sections vary in size depending on the recommended portion of each food a person should eat. A circle shape next to the plate represents dairy products, especially milk. 6 Viewing the icon online allows consumers to click on each section of the plate for more information. Functions of Foods Food is any material, solid or liquid, which after ingestion, digestion and absorption is used to build and maintain body tissues, regulate body processes and supply energy. Foods provide: Water (environment in which cells live) Fuel for energy (so that cells can do their work) Building blocks (nutrients that cells use to build and repair themselves) Metabolic regulators (nutrients that cells use to coordinate life’s processes) The six essential nutrients and their functions Carbohydrates Provide energy and heat Fats Provide energy and heat Proteins Build and repair body tissue Provide energy and heat Vitamins Regulate body functions Minerals Regulate body functions Water Regulate body functions 7 1. Energy and Heat: Dietary carbohydrates: starches and sugars are body’s primary source of fuel for heat and energy. They also maintain the body store of quick energy as glycogen. Each gram of carbohydrates yields 4 calories. Carbohydrates should provide 5066% of the total calories. Dietary fats: provide the body with heat and energy. It is the most concentrated form of energy yielding 9 calories/gm. Fats should provide no more than 25-30% of the total calories, with at least 50% of this amount being unsaturated fats from plant sources. Dietary proteins: the body may use dietary or tissue proteins to obtain energy when the supply of fuel from carbohydrates and fats is not enough. The fuel factor for protein is 4 calories. Protein should provide 15-20% of the total calories. 2. Tissue building: Proteins: primary function is tissue building. Dietary protein provides amino acids, the building units necessary for constructing and repairing body tissues. This is a constant process that ensures growth and maintenance of a strong body structure as well as vital substances for the tissue function. Minerals: such as calcium and phosphorus, which build and maintain bone tissue. Iron is part of Hemoglobin. Vitamins: Vitamin C is involved in developing the cementing intercellular ground substance. The substance helps build strong tissue and prevents tissue bleeding. 8 Fat: Fatty acids help build the central fat substance of cell walls, which promotes transport of fat-soluble material across the cell wall. 3. Regulation and control: All the chemical processes in the body needed for providing energy and building tissue are regulated and controlled to maintain a smooth, balanced operation. Nutrients that help regulate body processes are: Vitamins: many vitamins function as coenzyme factors. They are components of cell enzymes that control chemical reactions in cell metabolism (for example most of the b-complex vitamins). Almost every action in the body requires the assistance of vitamins. Minerals: many minerals serve as coenzyme factors such as cobalt, which is a central constituent of B12 vitamin (antipernicious anemia vitamin). Water and fibers: function as regulatory agents. Water is the fundamental agent for life, providing the essential case for all the metabolic processes. Fibers help in regulating the passage of food materials through the gastrointestinal tract and influence the absorption of various nutrients. Balanced Diet: 1. Adequate (provides enough of each essential nutrient, fiber and energy). 2. Balanced (does not over emphasize one food type or nutrient at the expense of another). 9 3. Caloric controlled (provides the desired energy for the body). 4. Moderate (does not provide excess intakes of fat, salt, sugar). 5. Variety (different foods to provide different nutrients). 6. Energy intake balanced with energy expenditure (calories in = calories out). Digestion, absorption and metabolism Digestion: The process whereby food is broken down into smaller parts (absorbable units), chemically changed, and moved through the gastrointestinal (GI) system. The process of digestion begins in the mouth. Digestive system: All body structures that participate in digestion. Digestion is of two parts: 1. Mechanical (teeth: crush large pieces of food into smaller ones; peristalsis: wavelike muscular contractions of the GI tract that push its contents along) 2. Chemical (hydrolysis: addition of water to break a molecule into smaller pieces; digestive enzymes: proteins that act on food substances, causing them to break down into simpler compounds) Digestion in the mouth: Chewing food and mixing with saliva (salivary amylase), initiates the digestion of carbohydrates. Salivary amylase acts on starch (very little is changed) Digestion in the stomach: Gravity and peristalsis transfer food down the tract. Stomach mixes food with gastric juices. Gastric juices: 10 Pepsin → Protein Rennin → Proteins in milk Gastric Lipase → Emulsify fat Gastric juices contain HCL Functions of HCL: - Break down food to make them easily attacked by the enzymes. - Provides the acid medium necessary for the action of pepsin. - Increases the solubility of calcium and iron salts to enhance their absorption. Destroys bacteria present in food. Mucus, a thick, slippery, white substance that coats the stomach’s cells, is secreted by the goblet cells of the stomach wall to protect themselves from gastric juice. Peristalsis moves the chyme towards pylorus, which is then released gradually into the duodenum (first part of the small intestines). Digestion in the small intestine: Chyme in the duodenum, specifically fat, stimulates the secretion of a hormone cholecystokinin (CCK), which causes the gallbladder to contract to release bile into the duodenum. Bile is produced in the liver and stored in the gallbladder. Bile has the function of fat emulsification (brings fat into suspension so enzymes can act upon them). Chyme stimulates the pancreas to secrete pancreatic juices into small intestine. The pancreatic juice contains enzymes that act on all three energy nutrients. Pancreatic juices: 11 - Pancreatic amylase (split starch to maltose) - Trypsin (break down proteins to smaller molecule) - Lipase (break down fats to fatty acids and glycerol) - Sodium bicarbonate, which is basic (a neutralizing agent) Intestinal juices (cells of the intestinal wall): lactase, maltase, sucrase, peptidases. Most of the other nutrients-vitamins, minerals, and water-need no such disassembly; some are altered slightly, but most are absorbed as they are. Absorption: The passage of nutrients into the body fluids and tissues. Nutrients must be in simplest form Carbohydrates → glucose, galactose, fructose Proteins → amino acids Fat → fatty acids and glycerol Most absorption of nutrients occurs in the small intestine through villi, fingerlike projections from the folds of the small intestine, which are composed of the microvilli, hairlike projections on each cell of every villus that trap nutrient particles and transport them into cells. Large intestine absorbs water and salts and collects bulk. In healthy individuals more than 90% of the nutrients are absorbed. Metabolism: Complex process that changes the nutrients in order to produce energy, which form tissues, and maintain control and regulation over body functions. Nutrients undergo oxidation Carbohydrates, fats Co2 + H2 O 12 Proteins Co2 + H2O + N Anabolism: the formation of complex molecules from simpler ones Catabolism: the breakdown of molecules to simpler ones like in surgery burns and during period of high fever. Metabolism is regulated by the thyroid gland. 13 Carbohydrates Definition: Carbohydrates are organic compounds that consist of carbon, hydrogen, and oxygen arranged as monosaccharides or multiples of monosaccharides. All carbohydrates except dietary fibers provide 4 kcal/g. Sugars and Starches Nature: Carbohydrates are formed from green plants through photosynthesis by which sugar is formed from Co2 and H2O by the aid of sunlight and chlorophyll. Functions: 1. Provide energy for body functions and heat to maintain body temperature. 2. Spare proteins for energy. 3. Aid in the synthesis of non-essential amino acids. 4. Required for the complete oxidation of fat. 5. Lactose increases the absorption of calcium and phosphorus and favors the growth of certain intestinal bacteria that synthesize some of the B-complex vitamins. 6. Gives flavor and texture to the diet. Daily Requirements: The daily diet should not contain less than 100 gms of carbohydrate. About 55 to 60% of the total caloric intake should be provided through carbohydrates. Sources: Cereal grains (rice, wheat, corn, oats, rye). Green leafy vegetables are high in fibers. Roots, tubers and seeds contain more complex carbohydrates (corn, potatoes, dried peas, beans). 14 Fruits contain sugars and fibers. Sweets provide different types of sugars. Animal sources include lactose in milk and glycogen in meats (limited extent). Classification: Class Examples Monosaccharides (single sugars) Glucose Fructose Galactose Disaccharides (double sugars) Sucrose Maltose Lactose Polysaccharides (complex carbohydrates) Starches Glycogen Dextrin Dietary Fibers Monosaccharides (simple carbohydrates): Simplest form of carbohydrates. Requires no digestion and are absorbed directly from the small intestine. Disaccharides (simple carbohydrates): Lactose composed of glucose and galactose. Principal carbohydrate of milk Maltose composed of two glucose molecules. Whenever starch breaks down Fermentation process yields that yields alcohol Minor constituent of a few foods 15 Sucrose composed of glucose and fructose. Natural sweetness of fruits, vegetables, and grains Refined to make table sugar These carbohydrates and all the other energy nutrients are put together and taken apart by a similar chemical reaction: condensation and hydrolysis. Must be changed to simple sugars before they can be absorbed. Maltose is an intermediate product in the digestion of starch inside the body. Polysaccharides (complex carbohydrates): Starch is the plant storage form of glucose (long, branched or unbranched chains of hundreds or thousands of glucose molecules). Derived from plants Richest in grains; wheat or rice, in tubers such as potatoes, and in legumes such as peas and beans. Glycogen is the form in which carbohydrates are stored in the body (liver and muscles). Dextrin is a digestible polysaccharide that is an intermediate product from the hydrolysis of starch. Fibers provide structures in stems, trunks, roots, leaves, and skins of plants, which are compose of a variety of monosaccharides and other carbohydrate derivatives. 16 Digestion, Absorption and Metabolism: The goal of digestion is to reduce the complex and double sugars to simple sugars. Digestion Salivary amylase Mouth: cooked starch Stomach: No action. Acid inactivates salivary enzyme. Small intestine: Starch Sucrose Small Poly, Maltose Amylase Sucrase Maltose Glucose, Fructose Maltase Maltose Lactose 2 Glucose Lactase Glucose, Galactose Absorption Small Intestine: Metabolism Glucose absorbed. Fructose and galactose can eventually become glucose after being processed in the liver. Glucose Oxidation Co2 + H2O + energy Changed to glycogen and stored in liver and muscles. Changed to fat and stored in fatty tissues. 17 Dietary fiber - Divided into two groups - Fibers that are not soluble in water (structural fibers): whole wheat and rye, wheat bran, seeds, nuts. - Water-soluble (nonstructural): apples, grapes, plums. Citrus fruits, oatmeal, oat bran, beans. Health benefits of fibers: Increase sense of fullness Reduces energy consumption, which helps in weight control. Prevent constipation. Increase fecal weight (promotes bowel movements). Help prevent bacterial infection. Reduces colon cancer. Improve the regulation of blood sugar (delaying glucose absorption). Lower the blood cholesterol and triglycerides (benefits heart health). Glucose in the body: Every body cell depends on glucose for its fuel to some extent, and ordinarily, the cells of the brain and the rest of the nervous depend primarily on glucose for their energy. Homeostasis: the body must maintain blood glucose within limits that permit the cells to nourish them-selves. If the glucose falls below normal, the person may become dizzy and weak; if it rises above normal, the person may become fatigued. Regulating hormones: 18 o Primarily by two hormones (from cells in the pancreas): insulin, which moves glucose from the blood into the cells, and glucagon, which brings glucose out of the storage when necessary. o Epinephrine: another hormone of the adrenal gland that modulates the stress response. Like glucagon, it works to release glucose from the liver glycogen to the blood. 19 Proteins Definition: - Proteins are large, complex, nitrogen containing compounds. - In addition to the carbon, hydrogen, and oxygen that carbohydrates and lipids contain, proteins also contain nitrogen. - Each gram of nitrogen = 6.25g protein. - Amino Acids: building blocks of proteins. Each contains an amino group (NH2), a hydrogen atom, an organic acid/carboxyl group (COOH), and a distinctive side group, all attached to a central carbon atom. - Side group is a unique structure that differentiates one amino acid from another. - The kinds of amino acids, the order in which they are arranged, and the frequency in which they are used in a chain determines the kind of protein. - About 20 AAs with 20 different side chains make up most of proteins of living tissue. Classification: Proteins are made up of about 20 common amino acids. Amino acids are classified as essential (those the body can’t make - that must be supplied by the diet) and nonessential (can be synthesized in the body). Essential Amino Acids Histidine (His) Valine (Val) Isoleucine (Ileu) Lysine (Lys) Leucine (leu) Methionine (Met) Phenylalanine (Phe) Threonine (Th) Tryptophan (Try) 20 Non-essential amino acids Alanine Cysteine Proline Arginine Glutamic acid Serine Asparagine Glutamine Tyrosine Aspartic acid Glycine Proteins: - Cells link AAs end to end in a virtually infinite variety of sequences to form thousands of different proteins. Each amino acid is connected to the next by a peptide bond. - The unique shapes of proteins enable them to perform their various tasks in the body. o Hemoglobin – packs the red blood cells and carries oxygen – is made of four associated polypeptide chains, each holding the mineral iron. - Heat, acid, or other conditions may disturb proteins’ stability, they undergo denaturation, in which they uncoil and lose their shapes and, consequently, their ability to function. Daily Requirements: - Many factors determine the requirements (body size, protein quality, new tissue requirements, stress,…). - 0.8 g/kg body weight for adults. - 2.2 g/kg body weight for infants 0-6 months - 1.6 g/kg for infants 6-12 months. - 28 g/day for children 7-10 years. - 71 g/day for pregnant and lactating. 21 Nutritional Quality of Proteins: The protein quality is of great concern, especially in countries where malnutrition is of great concern. Low quality proteins fail to provide enough of all the essential amino acids needed to support the body’s work. Complete Protein: - Contains the kinds and amounts of essential amino acids to support maintenance & growth in relatively the same amounts that human beings require. Generally proteins derived from animals (milk, eggs, meat, poultry, Fish) - Gelatin is a exception, it lacks tryptophan and cannot support growth and health as a diets sole protein. Partially complete Protein: - Protein from plants in which one or more essential amino acids are supplied in amounts inadequate for tissue synthesis (legumes, grains, nuts) Incomplete Protein: - Some plant proteins are notoriously incomplete, in which one or more of essential amino acids are absent (corn and soy proteins). High quality protein: an easily digestible complete protein (egg protein, assigned a value of 100). Measurement of protein quality: Wt gain (g) - Protein Efficiency Ratio (PER) = Protein fed (g) Proteins of high quality have a PER of 2.5 or better. Official method for assessing protein quality, and it is still used to evaluate proteins for infants by the United States and Canada. 22 - Biological value (BV) is measuring nitrogen content of the food eaten and the nitrogen content of the urine and feces (protein nitrogen absorbed). A BV of 70 or more is considered adequate for growth. Sources: - Animal sources include milk, eggs, cheese, meat, poultry, and fish. Protein in these foods provides all the essential amino acids. - Plant sources are beans, lentils, and other legumes, breads & cereals, nuts, and seeds. Protein from these sources must be complemented with another animal or plant proteins. Functions of Protein: 1. Supporting growth and maintenance. 2. Supplies some energy upon need (4 kcal/g). 3. Supplies essential substances necessary for the construction and proper functioning of body compounds (enzymes, hormones, regulators of fluid balance, acid-base regulators, hemoglobin, transporters, antibodies, and others such as being integral parts of most body structures as skin, bones, and muscles). 23 Digestion, Absorption, and Metabolism: The goal of digestion is to release the amino acids that make up the protein molecule. Digestion Mouth Crushed and moistened, mix with saliva Gastric Pepsin Stomach Protein proteoses Rennin Milk casein Small Intestine protein Trypsin* peptones calcium caseinate peptones Erepsin Amino acid Absorption Small intestine in the form of amino acid Metabolism - In the stomach: o HCL uncoils protein strands and activates stomach enzymes (pepsinogen to pepsin). o Pepsin cleaves proteins – large polypeptides – into smaller polypeptides and so AAs. - In the intestines: o Pancreatic and small intestinal enzymes split polypeptides further (tripeptides, dipeptides, and AAs) 24 o Intestinal proteases hydrolyze peptides and then cells absorb them. Amino acids - Build new tissues - Repair old tissues - Deamination (if not needed): Nitrogen removed urea excreted Carbon, hydrogen, oxygen glucose Clinical Problems: Protein excess: - Protein intake urinary loss of Ca - protein intake based on increased amount of meat, poultry, whole milk in the diet will lead to increase intake of saturated fat. - Protein rich foods are expensive this may lead to exclusion of other foods that are needed for minerals and vitamins from the diet. Protein deficiency: - Nutritional edema - Reduces the immune response Protein-energy malnutrition (PEM): a deficiency of protein, energy, or both, including kwashiorkor, marasmus, and instances in which they overlap. - Kwashiorkor: older infants and young children (1 to 3 yr). The protein content of the food is law. - Acute PEM - Protein deficiency, illness such as measles or other infection - Loss of body wt and body fat not as severe as in marasmus, edema (distinctive feature), belly bulges with a fatty liver. 25 - Marasmus: Infancy (less than 2 yr). The infant is fed a diet low in calories and protein. - Chronic PEM - Children look like little old people – just skin and bones, extreme loss of muscle and fat. - Muscles including heart waste and weaken. In all cases, children are likely to develop diarrhea, infections, and multiple nutrient deficiencies. 26 Fats Composition - Composed of three chemical elements: Carbon, hydrogen, and oxygen. - Fat is often used to refer to all the lipids, including triglycerides (fats and oils), phospholipids, and sterols. - The triglycerides - composed of one glycerol molecule attached to three fatty acids – predominate, both in foods and the body. - Each gram of fat yields 9 kcals. Fatty acids - Organic acids – a chain of carbon atoms with hydrogens attached – that has an acid group (COOH) at one end and a methyl group (CH3) at the other end. - Some fatty acids have short chains (fewer than 6 carbon atoms), others have medium length carbon chains (6-10 carbon atom), and the most commonly occurring in diet has long chains (12-24 carbon atoms). - Long chain fatty acids include meats and fish; short and medium chains primarily in dairy products. - Fatty acids maybe saturated or unsaturated depending on the amount of hydrogen in their composition. - Saturated if there is a single bond between the carbon atoms (fully loaded with hydrogen atoms and contains only single bonds between its carbon atoms). - Unsaturated if there is a double bond between two carbon atoms (hydrogens missing and presence of double bonds is an indication of unsaturated fatty acids). - One double bound monoustaturated. - Two or more double bounds polyunsaturated. 27 Classification of lipids - Triglycerides (the chief form of fat in the diet and the major storage form of fat in the body; composed of a molecule of glycerol with tree fatty acids attached), and their component parts, fatty acids (few occur free in foods or in the body). - Phospholipids are fats in which another group has replaced at least one of the fatty acids. - Best-known phospholipid is lecithin. - Each lecithin has a backbone of glycerol with two of its three attachments sites occupied by fatty acids and a phosphate group with a choline molecule occupies the third site. - Unique chemical structure that allows them to be soluble in both water and fat. - Part of cell membranes; food industry uses them as emulsifiers. Sterols are compounds with a multiple-ring structure. Many vitally important body compounds are sterols; among them are bile acids, the sex hormones (testosterone), the adrenal hormones (such as cortisol), and vitatamin D, as well as cholesterol (most famous sterol that the body makes and uses for its functioning). - Cholesterol in the body can serve as the starting material for the aforementioned compounds. - Structural component of cell membranes (cholesterol). Properties - Fats are insoluble in water, but soluble in ether, chloroform, benzene, and acetone. - Rancidity (the change in flavor and odor of fats when they are oxidized) occurs specially in fats that have a high proportion of unsaturated fatty acids. - Hydrogenated fats are polyunsaturated vegetable oils in which hydrogen has been added commercially to double bond carbons (monounsaturated and 28 polyunsaturated fats) making the fats more saturated (solid) and more resistant to oxidation by a process known as hydrogenation. - Molecules that remain unsaturated after processing change shape from cis to trans, trans-fatty acids. - Trans fatty acids have health effects similar to those of saturated fats. Functions 1. Fat foods furnish 9 kcal/g; provide the body with energy. 2. Spare the burning of protein for energy. 3. Provide insulation under skin; help to maintain constant body temperature. 4. Serve as shock absorbers, supporting and cushion vital organs. 5. Facilitate the absorption of fat-soluble vitamins A, D, E, & K. 6. Food fats contribute flavor, palatability, and satiety to the diet. Essential Fatty Acids Human body can make all except two and therefore, must be supplied by the diet: - Linoleic acid (18-carbon omega-6 fatty acid with 2 double bonds). - Linoleic acid is converted to arachidonic acid in the body. Arachidonic acid is required for normal growth, healthy skin, regulation of cell permeability, strength of capillaries, transport and metabolism of cholesterol, and as a precursor of prostaglandin. - Linolenic acid (18-carbonomega-3 fatty acid with 3 double bonds). - Needed so body can make EPA (eicosapentaenoic acid) and DHA (docosahexanoic acid). - These are essential for normal growth and development, and may play an important role in the prevention and treatment of heart disease, hypertension, arthritis, and cancer. 29 - Both, in addition to serving as structural parts of cell membranes, they make eicosanoids – powerful compounds that help regulate blood pressure, blood clot formation, and the immune response to injury and infection. Recommended Intakes of Fat There is no daily-recommended allowance for fat. Fats should provide no more than 30% of the total caloric intake. Other recommendations concerning fats are: - Reduce saturated fat intake to less than 10% of calories, increase polyunsaturated fats to about 10% of calories. - Reduce cholesterol intake to less than 300 mgs daily. Food sources - Animal sources are whole milk, butter, egg yolk, cheeses, and cream. - Plant sources are vegetable oil (corn, sunflower, sesame, etc.) and salad dressings made from oils, nuts, and olives. 30 Digestion, Absorption, and metabolism of fat Almost all the digestion of fat occurs in the small intestine. Fat stimulates the secretion of hormone CCK, which causes the gallbladder to contract so that the stored bile is released into the small intestine. Bile breaks up the fat into tiny particles and hold them in suspension in the watery intestinal content: this is known as emulsification. Digestion Mouth: No significant action, fats begin to melt (at body temp) Lingual lipase plays a small role in fat digestion Stomach: fats G. Lipase Fatty acids and glycerol P. Lipase* Small intestine: emulsified fats Monoglycerides, fatty acids I. Lipase** aand glycerol Absorption Small intestine: Glycerol and fatty acids monoglycerides and fatty acids absorbed into blood stream new fat Metabolism Oxidized for energy Stored in adipose tissue Synthesis of phospholipids *Pancreatic lipase **Intestinal lipase In the large intestine: some fat and cholesterol trapped in fiber, exit in feces. 31 Transport: The body makes four main types of clusters of lipids and proteins that are used as transport vehicles for fats. As a group, these vehicles are known as lipoproteins, and they solve the body’s problem of transporting fatty materials through the watery blood stream. Chylomicrons: They transport diet –derived lipids (mostly triglycerides) from the intestine to the rest of the body. VLDL: very low-density lipoprotein: made primarily by the liver cells to transport lipids to various tissues in the body; composed primarily of triglycerides. LDL: low density lipoprotein: derived from VLDL lipoproteins as cells remove triglycerides from them; chief carrier of cholesterol (bad fat). HDL: high-density lipoprotein: high in protein: appear to reduce the risk of coronary heart disease (good fat). Lipoprotein that transports cholesterol and other lipids back to the liver from the cells for recycling or disposal. Risk factors associated with increased fat intake: Obesity Cardiovascular diseases, Atherosclerosis, stroke, myocardial infarction Hypertension Diabetes Some types of cancer 32 Energy metabolism The body’s need for energy: * The human body requires fuel to do its work. The energy needed for the body takes priority over the maintenance and building of tissues or the regulation of body functions. * Glucose-from carbohydrates and glycerol and fatty acids-from triglycerides provide most of the body’s energy needs. However, if the supply is inadequate amino acids-from proteins will also be used for energy. Therefore: * Glucose, fatty acids, glycerol, amino acids + oxygen Energy + carbon dioxide + water * The release of energy occurs during a series of pathways that ultimately lead to the tricarboxylic acid cycle (TCA cycle) and electron transport chain (ETC), which produce the greatest amount of energy. * The energy released during catabolism is often captured by go-between molecules that can easily transfer that energy to other compounds. These molecules are sometimes called the body’s “common energy currency”, or “high-energy compounds”. One such compound is ATP. * Released energy is taken up in tiny packets known as ATP (adenosine triphosphate). Energy can then be released from these tiny packets by breaking one of the phosphate bonds, leaving a compound known as ADP. ADP is rapidly regenerated to ATP. Units of energy: * Kcal is used to measure the energy value of the foods. Kcalories are units of heat energy. * Joule: mechanical equivalent of heat. 1 kcal = 4.2 kJ 1kJ = 0.24 kcal 33 Caloric value of nutrients /g 1 g CHO = 4 kcal = 17 kJ 1 g fat = 9 kcal = 37 kJ 1 g protein = 4 kcal = 17 kJ * A bomb calorimeter is an instrument that measures the heat energy released when foods are burned, thus providing an estimate of the potential energy of foods. Components of Energy Expenditure (energy needs of the body): Heat is released whenever the body breaks down food for energy and again when that energy is used to do work. The body’s generation of heat is known as thermogenesis. The total energy a body spends reflects three main categories of thermogenesis: 1. Basal thermogenesis (basal metabolism). 2. Exercise-induced thermogenesis (physical activity). 3. Diet-induced thermogenesis (thermic effect of food). A fourth category is sometimes involved – adaptive thermogenesis (energy of adaptation). * The total energy requirement of the body includes the basal metabolism, energy needed for activities, the influence of food, the environmental temperature, and the special needs for tissue building during growth, pregnancy and lactation. * Basal metabolism (BM): energy needs of the body while at rest: includes the involuntary activities of the body. * Basal metabolism is the largest component of energy expenditure (about 2/3 of the energy the average person spends). 34 * It includes bodily activities that we can’t control. Examples are breathing, heart beating, circulation of blood, peristaltic movements of the intestinal tract, and the metabolic activities – in short, they support all the basic processes of life. * The basal metabolic rate (BMR) is the rate at which the body spends energy for these maintenance activities. The rate may vary from one person to another. * BMR is regulated by the thyroid gland. Factors affecting BMR: * Body size: Greater skin surface loses more heat. * Age: Lean body mass diminishes with age, slowing the BMR. * Height: In tall, thin people, the BMR is higher. * Sex: BMR is 10% higher in men than in women * Muscle mass and body fat: athletes have higher rate than the non-athlete (the more the muscles mass the more heat loss). * Fever: fever elevates BMR. For each degree increase in body temperature the BMR increases 13%. * Stresses: Raises the BMR (including many diseases and certain drugs). * Environmental temperature: Both heat and cold raise the BMR. * Fasting/starvation: Lowers the BMR. * Malnutrition: Lowers the BMR. * Hormones: The thyroid gland hormone thyroxin, for example, can speed up or slow down the BMR. * Growth: Building new tissues accounts for a high rate of BMR in infants. Increase in metabolism during the growth period of adolescence and also for the development of the fetus during the second and third trimesters of pregnancy. Therefore, in children and pregnant women, the BMR s higher. * Smoking: Nicotine increases energy expenditure. * Caffeine: increases energy expenditure. * Sleep: BMR is lowest when sleeping. 35 Diet-Planning Guides: Diet planning is the bridge between nutrition theory and the food on the table. To plan a diet that achieves all of the dietary ideals, a person needs tools as well as knowledge. To help people plan diets, two most widely kinds of guides are available: 1. Food group plans (FGP): - The U.S. Department of Agriculture (USDA) released a new food guide, MyPlate, to replace the Food Guide Pyramid. - Describes the daily number of servings recommended for gender and age groups. - The five-food group (MyPlate) is part of a larger communication initiative based on 2010 Dietary Guidelines for Americans to help consumers make better food choices. - The plan can provide a reasonable foundation for diet planning. - For information on what’s in each group, how much is needed, what counts as a cup, and health benefits, visit www.ChooseMyPlate.gov. Problems with the five food groups - It does not specify calorie amount. - A person may fail to meet the daily needs for some nutrients. - It ignores the needs of vegetarians. In general food group plans organize foods by their nutrients and origins to provide patterns of food intake that cover nutrient needs. 2. Exchange lists: - Lists of foods that can be used with food group plans to help achieve kcalorie control and moderation. - The system sorts foods into three main groups by their proportions of carbohydrate, fat, and protein and specifies their portion sizes. 36 - Provides a sense of which foods are similar to each other in their energy and selected nutrient contents. - Can facilitate weight control, controls fat intake (saturated vs. polyunsaturated), fiber and salt intakes for preventing many diseases - Organizes foods into three main groups according to their CHO, fat and protein contents (and therefore, total energy content as well). Foods on any single list can be used interchangeably. Problems with the exchange system: - It pays strict attention to portions. - Foods are based on their content of CHO, fat, protein and not their content of vitamins and minerals. In general exchange system facilitates kcalorie control because foods on each list provides approximately equal amounts of carbohydrate, fat, and protein, as well total kcalorie. Dietary guidelines for disease prevention: Eat a variety of foods Maintain healthy weight Choose a diets low in fat, saturated fat, and cholesterol Choose a diet with plenty of vegetables, fruits, and grain products Use sugar in moderation Use salt and sodium in moderation 37 CARBOHYDRATE Glucose PROTEIN NH2 Amino Acid Pyruvic Acid Glycerol Acetyl CoA Fatty Acid NH2 TCA Cycle CO2 H2 O Energy 38 FAT Exchange List for Meal Planning -------------------------------------------------------------------------------------------------------Groups/Lists Carbohydrate Protein Fat Calories (grams) (grams) (grams) -------------------------------------------------------------------------------------------------------CARBOHYDRATE GROUP: Starch Fruit Milk, skim Milk, reduced fat Milk, whole Other Carbohydrates Vegetables 15 15 12 12 12 15 5 3 -8 8 8 varies 2 ---5 8 varies -- 80 60 90 120 150 varies 25 MEAT AND MEAT SUBSTITUTE GROUP Very lean -Lean -Medium-fat -High-fat -- 7 7 7 7 0-1 3 5 8 35 55 75 100 FAT GROUP -- 5 45 -- _____________________________________________________________________ (ADA & A Diet A, 1995) 39 Nutrition Assessment Nutritional assessment evaluates a person’s health from a nutrition perspective. Many factors influence or reflect nutrition status. Therefore, nutritional assessment includes: Anthropometric measurments. Physical examinations (clinical assessment). Historical information (dietary assessment). Biochemical analyses (laboratory evaluations). Anthropometric Measurments Anthropometrics are physical measurments that reflect body composition and development. Height Weight Skinfold Circumferences Height: Malnutrition and certain illness during growing period can prevent an individual from reaching optimal height. Best obtained with standing straight with the back to a measuring device attached to a vertical surface. For infant and very young children recumbent (lying down) length is measured. Weight: Measured using a beam-balance (preferred) or electronic scales – most accurate types. 40 Pediatric scale is used for measuring the weight of infants and children too young to stand. Body mass index: An index of a person’s weight in relation to height, which is useful for estimating the risk to health associated with malnutrition. BMI = Weight, kg / Height, m2 BMI < 18.5 = underweight BMI 18.5 to 24.9 = normal BMI 25 to 29.9 = overweight BMI 30 = Obese Skinfold/fatfold Measures: Means for assessing the energy reserves in the form of fat. Help distinguish between professional athletes and overweight individuals. Triceps (TSF) and subscapular (SSF) measurements are most frequently taken. Measurements are conducted using a caliper. Other Measures of Body Fat and Lean Tissue: Waist Circumference Waist-to Hip Ratio Hydrodensitometry Bioelectric Impedance Clinicians use many other methods to estimate body fat and its distribution. Physical Examinations (clinical assessment) 41 Physical examinations are used to search for signs of nutrient deficiency or toxicity. Many signs appear most rapidly in parts of the body where cell replacement occurs at a high rate Such as in the skin, hair, eyes, and digestive tract (including the mouth and tongue), which are most frequently examined for possible nutritional deficiencies. The epithelial and mucosal cells have a rapid turnover rate so symptoms of deficiencies may appear earlier. Advantages: non-threatening, easy to obtain, most informative and communicate much information about nutrition health. Disadvantages: many physical signs are nonspecific; they can reflect any of several nutrient defeciencies as well as conditions not related to nutrition. Historical Information (dietary assessment) Clues about present nutrition status become evident with a careful review of a person’s historical data. Historical data used in nutrition assesments includes the following: Health history: current and previous health problems and family health history that affect nutrient needs, nutrition status, or the need for intervention to prevent health problems. Socioeconomic history: personal, cultural, financial, and environmental influences on food intake, nutrient need, and diet therapy options. Drug history: mediations, dietary supplements, and alternative therapies that affect nutrition status. Diet history: nutrient intake excesses or deficiencies and reasons for imbalances. 42 Evaluation of the diet history provides a record of a person’s eating habits and food intake and can help identify possible nutrient imbalances. Food choices are an important part of lifestyle and often reflect a person’s thoughts. Methods for collecting intake information includes the following: 1. 24-hour recall: The easiest and the most common methods of obtaining dietary information. Provides data for one day only, in which the assessor asks the client to recount everything eaten or drunk in the past 24 hours or for the previous day. Disadvantages: Patient may not be able to recall the foods eaten. Patient may not be able to estimate the amount of food eaten. Patient may not be telling the truth. The intake may not be a typical one. 2. Food frequency questionnaire: A checklist of foods on which a person can record the frequency with ehich he or she eats each day. Helps pinpoint food groups and therefore, nutrients that may be excessive or deficient in the diet. Does not provide information on the quantities. Useful when used with the 24-hour recall, enabling the assessor to double check the accuracy of the information obtained. 3. Food record: An extensive, accurate log of all foods eaten over a period of several days or weeks, including the quantity and method of preparation. A food record that 43 includes associated information such as when, where, and with whom each food is eaten is sometimes called a food diary. 4. Observation of food intake: Members of the care team can obtain information about food intake and factors affecting it in the hospital and at home through observing the clients. 5. Usual intake: An assesor asks questions about a person’s usual intake until a typical daily pattern emerges. Useful especially in verifying food intake when the past 24 hours have been atypical, as well as helps the assesor verify food habits. Difficult for a person whose diet intake varies widely from day to day. Nutrition History: Collect information on the general pattern of food intake and other factors influencing the patient’s food habits. Includes 24-hour recall, a food frequency list, an extensive interview and through reading the patient’s medical record. Estimating nutrient content of the diet: Dietary intake is evaluated by comparing it to some standards Biochemical Analyses (laboratory assessment) Biochemical analyses help to determine what is happening to the body internally. Common tests are based on analysis of blood and urine samples, which contain nutrients, enzymes, and metabolites that reflect nutrition status. Low nutrient concentrations in the blood may occur due to inadequate intake, impaired absorption, transport, or metabolism, increased excretion, or combinations of the above. 44 Nutrient levels including glucose, lipids, or minerals, hemoglobin, hematocrit, erythrocyte, leukocyte, etc. counts are used to measure nutrient levels. Low Hb can be obsereverd in cases of anemia, hemorrhage, and protien-energy malnutrition while elevated in dehydration. WBC may increase in cases of infections and leukemia RBC counts would decrease in anemia, chronic infectious diseases and hemorrahage and are elevated in dehydration. Serum albumin and serum transferrin are depressed in protein malnutrition Decreased lymphocyte counts are associated malnutrition, stress, trauma, and lowered immune response. 45 Vitamins - Vitamins are organic essential nutrients containing carbon, oxygen, and other elements that are required in tiny amounts for body processes, including functions that promote growth, reproduction, or the maintenance of health and life. - Vitamins do not provide energy but they enable the body to use the energy provided from fats, carbohydrates, and proteins. - Vitamins are found in minute amounts in natural foods. Eating a balanced diet can provide all the vitamins needed. - Vitamin deficiencies can occur if the diet is not balanced, or if so much alcohol is used. Just as an inadequate intake can cause harm, so can an excessive intake. - The amounts of vitamins people ingest daily from foods and the amounts they require are measured in micrograms or milligrams, rather than grams. Hypervitaminosis: excess of one or more vitamins. - Vitaminosis means without vitamins. This word followed by the name of a specific vitamin is used to indicate a serious lack of that particular vitamin. Preserving vitamin content in food (minimize nutrient loss): - Buy the freshest, unbruised vegetables and fruits. - Use raw vegetables and fruits whenever possible. - Prepare fresh vegetables and fruits just before serving. - Heat canned vegetables quickly and in their own liquid. - Follow package directions when using frozen vegetables or fruit. 46 - Use as little water as possible in cooking (boil water). - Save the cooking liquid for later use in soups, stews…..etc. - Store fresh vegetables and fruits in a cool dark place. Classification of vitamins: - Vitamins are grouped according to solubility. Vitamins A, D, E, and K are fatsoluble while the B vitamins and vitamin C are water-soluble. - Vitamins A and D are sometimes classified as hormones, and B vitamins can be classified as catalysts or co-enzymes that assist certain enzymes in the release of energy from food. Fat-soluble vitamins: - They require bile for their absorption due to being insoluble in water. - They travel through the lymphatic system within chylomicrons before entering the blood stream, where many of them require protein carriers for their transport. - Absorbed fat-soluble vitamins are stored primarily in liver and adipose tissue; therefore deficiencies of these vitamins are slower to appear. - Mega-doses of these vitamins can be toxic (since they are stored in liver). Vitamin A: Found in 2 forms 1. Active in the body: vitamin A “retinol, retinal, retinoic acid”. 2. Precursors of vitamin A: provitamin A, “Carotenoids”. Beta-carotene is the most studied and greatest vitamin A activity. Functions: - Essential for maintaining healthy eyes (promoting vision), skin (participating in protein synthesis and cell differentiation), and supporting reproduction and bone and tooth growth. 47 - Aids in the prevention of infections by helping to maintain healthy mucus membranes. Sources: - Retinoids are found in fat-containing animal foods, such as liver, fish liver oils, butter, cream whole milk, cheeses (from whole milk) and egg yolk. - Carotenoids are derived from plant foods such as yellow and dark green leafy vegetables, in yellow and orange fruit. Deficiency: - Night blindness: slow recovery of vision after flashes of bright light at night or an inability to see in dim light. - Blindness: progressive blindness caused by severe vitamin A deficiency. - Dry, rough skin (keratinization), epithelial tissues weaken, and decreased mucus secretion. - Increased susceptibility to infections: measles, pneumonia, severe diarrhea, malaria, lung disease etc. Vitamin D: - Found in 2 forms: D2 (ergocalciferol) and D3 (cholecalciferol). - Different from all other nutrients in that the body can synthesize it, with the help of sunlight, from a precursor that the body makes from cholesterol. Given enough time in the sun, people need no vitamin D from foods. - D3 is formed in humans by the sun’s ultraviolet rays that hit the precursor in the skin. - D2 formed is the plant version. - Vitamin D is a prohormone because it is converted to a hormone in the human body; vitamin D is heat stable and not easily oxidized. Functions: - Mineralization of bones including the teeth 48 - Promote calcium and phosphorus absorption from the GI tract - Regulation of calcium and phosphorus levels in the blood The bones grow stronger and denser as they absorb and deposit these minerals. Vitamin D is the director, but the star of the show is calcium. Sources: - Synthesized in the body through exposure to sunlight - Food sources of vitamin D include fortified milk, butter, egg yolks, liver, fatty fish and their oils, and fortified margarine. Deficiency: - Decreased calcium and phosphorus absorption (low production of the protein that binds calcium), which results in poor bone and tooth formation due to being undersupplied. - Young children develop rickets (growth retardation and skeletal deformities) bowed legs are often the most obvious sign. - Adults develop osteomalacia (softening of bone). - Osteoporosis is a condition of reduced bone density (a disease characterized by brittle, porous bones). Inadequate vitamin D sets the stage for a loss of calcium from the bones, which can result in fractures. Vitamin E: - Called tocopherols. Alpha-tochopherol is the only active vitamin E in the human body. - It deteriorates when exposed to heat. Functions: - Acts as an antioxidant 1. Protection of cell structure from the adverse effects of free radicals. 2. Prevents the oxidation of PUFA, but it protects other lipids and vitamin A. - Improves physical performance, enhances sexual performance, or cures sexual dysfunction in males. 49 Sources: wheat germ, vegetable and seed oils, leafy green vegetables, nuts, and margarine. (Animal foods are poor sources of vitamin E). Deficiency: - Primary symptom: increased rate of hemolysis in the RBCs (erythrocyte hemolysis), due to oxidation of PUFA in their membranes - Anemia - Neuromuscular dysfunction involving the spinal cord and retina of the eye. Vitamin K Functions: - Acts primarily in synthesis of blood clotting proteins. - Synthesis of bone proteins that regulate blood calcium. Sources: - Billions of bacteria in the GI tract (mainly in small intestines) make the vitamin; this source provides about half of a person’s needs. - Other half from: rich foods include green leafy vegetables, liver, and members of the cabbage family, fruits, cereals, and milk. Deficiency: - Defective blood coagulation (Hemorrhaging, uncontrolled bleeding). 50 Water-soluble vitamins: - Include B vitamins and vitamin C. - Absorbed directly into the blood. - Dissolve in water; circulate freely in water filled parts of the body. - Not stored in the body; kidneys detect and remove excess in urine. - Possible to reach toxic levels when consumed from supplements. Reminder – key info: Several B vitamins form part of coenzymes that assist certain enzymes in the release of energy from carbohydrate, fat, and protein. A coenzyme is a small organic molecule that associates closely with certain enzymes; many B vitamins form integral parts of coenzymes. B1 (Thiamin): Functions: part of coenzyme TPP (thiamin pyrophosphate) used in energy metabolism of all cells. Sources: whole-grain, fortified, or enriched grain products; moderate amount in all nutritious food. Deficiency: - Loss of appetite (anorexia), fatigue, nervous irritability and constipation. - Extreme deficiency causes the disease beriberi (characterized as wet, with edema or dry, with muscle wasting), a disease that affects the nervous system, heart and other muscles. B2 (Riboflavin): - sensitive to light Functions: - Essential for carbohydrate, fat and protein metabolism. 51 - Part of coenzymes FMN (flavin mononucleotide) and FAD (flavin adenine dinucleotide) used in energy metabolism. Sources: milk products (yogurt, cheese); enriched or whole grains; organ meats; dark green leafy veg. Deficiency: Ariboflavinosis: inflammation of the members of the mouth, skin, eyes, and GI tract. Cheilosis is sores on the lips and cracks at the corners of mouth. Dermatitis; eye sensitivity (burning, itching). B3 (Niacin): Other names: nicotinic acid, nicotinamide - Stable in foods, stand reasonable heat, acid and storage. - Functions: - Serves as coenzyme in energy metabolism. - Part of coenzyme NAD and NADP used in energy metabolism. Sources: meats, poultry, fish and peanuts, whole grain and enriched breads and cereals, and all protein containing foods. - Tryptophan (an amino acid) is a precursor of niacin. The body can make it from the amino acid tryptophan; 1 mg niacin equals 60 mgs tryptophan. 52 Deficiency: - Essential for the prevention of pellagra, a disease that produces the symptoms of diarrhea, dermatitis, dementia, and eventually death (often called “the four Ds”). - Other deficiency symptoms include blurred vision, abdominal pain, inflamed tongue, depression, fatigue apathy. Biotin: Functions and sources: - Part of a coenzyme used in energy metabolism, fat synthesis, amino acid metabolism, and gluconeogenesis. - Widespread in foods; organ meats, egg yolks; also produced by GI bacteria. Requirements: needed in very small amounts Deficiency: skin rash, hair loss, and neurological impairment (consumption of raw egg whites, more than two dozens every day for several weeks, which contain a protein than binds biotin and prevents its absorption). Pantothenic acid: Functions: Part of coenzyme A, used in energy metabolism. - Involved in the more than 100 steps in the synthesis of lipids, neurotransmitters, steroid hormones, and hemoglobin. Sources: Widespread in foods; organ meats, poultry, mushrooms, avocados, broccoli, whole grains. 53 Deficiency: Its symptoms involve a general failure of all the body’s systems and include fatigue, GI distress, and neurological disturbances. Vitamin B6: Occurs in three forms - pyridoxine, pyridoxal and pyridoxamine. Functions: part of coenzyme PLP (pyridoxal phosphate) used in amino acid metabolism. Enhances the conversion of tryptophan to niacin and to serotonin; also to make red blood cells (heme, nonprotein portion of hemoglobin). Sources: fish, poultry, meats, potatoes, a few other vegetables (green) including legumes, and fruits (purple) including noncitrus ones, and fortified cereals. Deficiency: early symptoms include depression, confusion; advance symptoms include abnormal brain wave patterns and convulsions; scaly dermatitis and anemia (small cell type – microcytic) are other symptoms. Folate: also known as folic acid or folacin, and chemical name is pteroylglutamic acid (PGA). - Destroyed by storage, processing, heat or oxidation. Functions: - Part of coenzyme THF (tetrahydrofolate) and DHF (dihydrofolate) used in DNA synthesis and therefore in new cell formation. 54 Sources: fortified grains, green leafy vegetables, legumes (black beans, kidney beans, and black eyed peas), liver and seeds. Requirements: Adults: 400 g/d Deficiency: Impairment of cell division and protein synthesis – processes critical to growing tissue. Two of the first symptoms are anemia and GI tract deterioration. “megaloblastic anemia”, a condition in which RBCs are large and immature, and unable to carry oxygen properly. Elevated homocysteine, which is an amino acid that cannot be broken down without adequate folate B12: (Cobalamin) Functions: Vitamin B12 and folate are closely related: each depends on the other for activation. Part of coenzyme methylcobalmin and deoxyadenosylcobalamin used in new cell synthesis; helps to maintain nerve cells; reform folate coenzyme. Sources: Animal products: meats, fish, poultry, eggs, dairy products, and fortified cereals. Deficiency: Most reflect inadequate absorption, not poor intake due to two reasons: a lack of HCL or intrinsic factor. 55 Deficiency disease, pernicious anemia, is caused by atrophic gastritis and a lack of intrinsic factor, and is characterized by abnormally large immature red blood cells. Deficiency symptoms include anemia of folate deficiency, sore tongue, fatigue, and degeneration of peripheral nerves progressing to paralysis. Vitamin C (Ascorbic acid): - Anti-oxidant properties (protects food from oxidation and defends body from free radicals). - Readily destroyed by heat, air alkalis. Functions: 1. Enhances iron absorption. 2. Collagen synthesis (a fibrous structural protein that strengthens blood vessels, forms scar tissue, provides matrix for bone growth). 3. Antioxidant, by losing its electrons to defend against free radicals. 4. Synthesis of hormones, including thyroxin. 5. Metabolism of amino acid. 6. Strengthens resistance to infection. Sources: Citrus fruits, tomatoes, potatoes, melon, strawberries, magoes, cabbage-type vegetables, and dark green vegetables (such as broccoli and bell peppers). 56 Deficiency: - Scurvy (a disease characterized by spongy and bleeding gums, loose teeth, sore joints and muscles. Symptoms of the disease includes bruises, poor wound healing, easily fractured bones). - Symptoms include bleeding gums, loose teeth, bruises and rough skin, poor wound healing, anemia and infection. 57 Minerals - Minerals are inorganic substances found in all body tissues and fluids. - They do not furnish energy and are stable in water. - Minerals are divided into two classes Major minerals (macrominerals) are those that occur in largest amounts in foods and in the body. Examples are Calcium, Phosphorus, Sodium, Potassium, Chloride, Magnesium, and sulfur. Trace minerals (microminerals) are those that occur in very small amounts in foods and in the body. Examples are Iron, Iodine, Zinc, Selenium, Fluoride, Copper, and Manganese. General Functions: - Bone and tooth formation - Constituents of soft tissues, vitamins, enzymes, and hormones - Nervous response and muscle contraction - Water and acid-base balance Dietary allowance: - RDA for eight of the elements is set - For other minerals a “safe and adequate” range of intakes has been recommended. - Based on weight, the allowance for infants, children, and teenagers are higher to allow for growth. - Allowances are also higher for pregnancy and lactation. Factors that affect the absorption of minerals: - Body need - The chemical form of the mineral 58 - Stomach acidity - Lactose improves Ca absorption - Ascorbic acid enhance the absorption of Ca, Fe, Zn - Some drugs and excess fiber bind minerals - Laxatives and diarrhea decrease absorption - Excess of some minerals decrease the absorption of other minerals - Damage to the intestinal mucosa interferes with the absorption of minerals MINERALS Major minerals FOOD SOURCES Milk Cheese Some dark green, leafy vegetables Calcium Phosphorus Milk and Cheese Lean meat Poultry Fish Whole grain cereals Legumes Nuts FUNCTIONS - - - - Magnesium Avocados Nuts Milk Whole grains Green, leafy vegetables Legumes Bananas - - Normal development and maintenance of bones and teeth Clotting of the blood Nerve irritability Normal heart action Normal muscle activity Activates enzymes Normal development and maintenance of bones and teeth Maintenance of normal acid-base balance of the blood Constituent of all body cells Necessary for effectiveness of some vitamins Constituent of bones, muscles and red blood cells Regulate the transmission of nerve impulses and activate enzymes including those involved in energy metabolism 59 DEFICIENCY - - - - Retarded growth Poor tooth and bone formation Slow clotting time Osteoporosis Poor tooth and bone formation Weakness Pain in bones Severe prolonged vomiting Kwashiorkor severe malabsorption disease Impair central nervous system activity MINERALS Sodium FOOD SOURCES Table salt Meat Milk and cheese Soy sauce Processed foods FUNCTIONS - Potassium Vegetables Fruits, especially oranges, Bananas, and prunes - Chloride Sulfur DEFICIENCY Water balance & osmotic pressure Acid-base balance Transmission of nerve impulse Muscle contraction Cell permeability - Nausea Exhaustion Muscle cramps Osmosis Fluid balance Regulate muscle contraction including heart muscle Cell metabolism - Muscle weakness Paralysis Confusion Abnormal heart beats Do not occur in normal conditions Nausea Exhaustion Table salt Meat Milk Eggs Processed foods - Osmosis Fluid balance Acid-base balance Formation of hydrochloric acid - All protein containing foods (meat, poultry, fish, eggs) - For building hair, nails, and all body tissues Constituent of all body cells Metabolism - - 60 - Unknown (no deficiency has been observed) MINERALS Trace Minerals Iron Copper Iodine Manganese Zinc FOOD SOURCES FUNCTIONS Red meats Fish Poultry Shell fish Eggs Legumes Dried fruits - Seafood Legumes Nuts Whole grain Cereals - Seafood Foods grown in soil bordering salt water Iodized salt - Whole grains Nuts Vegetables Protein containing foods: Seafood, especially oysters Liver Meat Eggs Milk - - Essential for formation of hemoglobin of the red blood cells and provision of oxygen to cells Constituent of cellular enzymes - Anemia: Characterized by weakness, dizziness, reduced resistance to infection, loss of weight, and pallor Essential for formation of hemoglobin and red blood cells Component of several enzymes - Anemia Diarrhea Liver damage Formation of hormones in thyroid gland that help to regulate growth development, and metabolic rate - Goiter (enlargement of the thyroid gland) Cretinism (a congenital disease characterized by mental and physical retardation) - Cofactor for several enzymes - Component of insulin and many enzymes Involved in making genetic material and proteins Immune reactions Transport of vitamin A Wound healing Taste perception The making of sperm Essential for growth - - DEFICIENCY 61 - - Unknown - Growth failure in children Loss of appetite Skin changes (dermatitis) Impaired wound healing Loss of taste Sexual retardation - Fluoride Fluoridated water Seafood - Cobalt Organ meats Muscle meats Milk Eggs Seafoods Organ meats Other meats Whole grain Some vegetables - Meats Unrefined grains Vegetable oils - Selenium Chromium - - Helps form bones and teeth; confers decay resistance on teeth A component of vitamin B12 necessary for formation of the red blood cells Part of an enzyme that defends against oxidation Regulates thyroid hormone - Susceptibility to tooth decay - Unknown - Associated with Keshan disease (predisposition to hear disease characterized by cardiac tissue becoming fibrous Unknown Associated with insulin Needed for energy release from glucose 62 Water In the body, water becomes the fluid in which all life processes occur. Water constitutes about 60 percent of an adult’s body weight and a higher percentage of a child’s. Water content is the highest in metabolically active tissues (muscles) Functions: * Component of most cells * Regulate body temperature * Act as lubricants around joints * Elimination of waste products * Act as a media for the chemical reactions * Transport of nutrients to the tissue * Serves as a solvent for mineral, vitamins, amino acids, glucose and other molecules Sources of water: * Fluids (water, tea, coffee) * Solid foods * Metabolic water Requirements: * Insufficient data to establish EAR or RDA for Water * Insufficient data available to make recommendations based on reduction of chronic risk diseases * BW can be lost quickly from PA and heat 63
