Components of a Balanced Diet-jan intake.docx
- 1. Components of a Balanced Diet There is the balance of different foods that determines whether a person’s diet is healthy or not therefore the types of food and drink we eat are very important as they are linked to our general health and wellbeing. A healthy diet can lead to longer and healthier life; reduce likelihood of disease and illness; it contributes to the amount of energy in the body, appearance, how we feel and the general health status thus chef’s should be aware of health issues relating to food consumption. a. Nutrients Nutrients are the part of foods that help the body to perform and maintain bodily function; this includes (movements, sight, growth and repair) The main functions of nutrients in the body include: - Energy Growth and Repair Regulation of Body Processes Carbohydrates Proteins Vitamins Fats Minerals Minerals Proteins Water Water Nutrients are broken down into 7 main categories namely; carbohydrates, proteins, fats, vitamins, minerals, water, dietary fibre - Carbohydrates Consists of carbon, hydrogen and oxygen with hydrogen and oxygen in the same proportion as in water. 6CO2 + 6H2O C6H12O6 + 6O2 Carbon dioxide (air) Water (soil) Glucose Released into the air Carbohydrates are synthesized (built up) by plants, with the help of sunlight, carbon dioxide in the air and water These elements combine to produce starch, sugar and cellulose all of which differ widely in texture, flavor and uses in cookery
- 2. Carbohydrates provide the greatest source of energy and can be divided into 3 sub groups 1. Monosaccharides Monosaccharide sugars commonly found in food contain six carbon atoms and have a general formulae C6H12O6 Common examples include: - - Glucose (dextrose) - Fructose (laevulose) - Galactose Sugars (saccharides) i.e. ordinary table sugars, cane sugars, sweets, honey, milk, fruit, fruit juices, syrup, sweet desserts 2. Disaccharides Are sugars that have a general formulae C12H22O11. They are formed when 2 monosaccharide molecules combine with the elimination of a water molecule Common examples include: - - Sucrose - Lactose - Maltose Starches (polysaccharides) i.e. bread, natural flours, corn, potatoes, cereals, rice, cassava, yams, maize, wheat They are the simplest form of carbohydrates and the end products of the digestion of carbohydrates and are absorbed in the form of glucose and simple sugars; used to provide heat and energy. There are several kinds of sugar - Glucose (found in the blood of animals, fruit and honey) - Fructose (found in fruit, honey and cane sugar) - Sucrose (found in beet and cane sugar)
- 3. - Lactose (found in milk) - Maltose (produced naturally during the germination of grain) It is found in fruits and vegetables of which sugarcane and beet containing the highest quantity of sucrose. Other forms of sugar i.e. Maltose; the sugar that is commonly found in cereal grains and used in beer making. It is not as sweet as sucrose Lactose is the type of sugar that is present in milk. The amount of sugar that is present depends on the type and source of the milk Properties of Sugars - Appearance and solubility All sugars are white, crystalline compound which are soluble in water - Sweetness All sugars are sweet but do not have the same degree of sweetness - Hydrolysis A disaccharide undergo through a process of hydrolysis to form monosaccharides. Hydrolysis is a process of chemical breakdown of a molecule by combination with water producing smaller molecules - Effect of heat When sugars are heated, they caramelize; a caramel is a sweet, brown substance and is a mixture of carbohydrate like compounds - Reducing properties All monosaccharides and polysaccharides with the exception of sucrose act as reducing agents and are therefore known as reducing sugars. 3. Polysaccharides Polysaccharides are condensation polymers of monosaccharides and are made up of many monosaccharide molecules joined together with the elimination of one water molecule at each link.
- 4. They have the general formulae C6H10O5 where ‘n’ represents a large number. Cellulose (dietary fibre) i.e. plentiful in certain vegetables i.e. lettuce, celery, fruit with skin, green legumes, leafy vegetables, whole grain cereals, millet Examples of polysaccharides includes: - - Starch - Cellulose - Glycogen - Pectin - Gums, alginates and agar Starches – Are made up of simple sugars, they do not dissolve in water like sugars do but becomes much easier to digest once cooked. Starches are present in many types of food but are particularly high in cereals, rice and root vegetables. If peeled and cut potatoes are left in water for awhile, some of the starch from the potatoes will leak and fall to the bottom of the bowl and appears as a smooth, silky and waxy white substance. Other products that are high in starch include flour and products made from flour such as pasta and bread Starch is present in the diet through the following foods: - - Whole grain (rice, barley - Powdered grains (corn flour) - Vegetables (potatoes, arrowroot) - Unripe fruit ( bananas) - Cereals (cornflakes) - Cooked starch (cakes, biscuits) - Pastas (macaroni) Starch is composed of a number of glucose molecules / particles, during digestion; starch is broken down into glucose.
- 5. It is often now referred to as dietary fibre or NSP (non-starch polysaccharide) Dietary Fibre – Unlike sugars and starches, dietary fibre cannot be digested, it does not provide the body with energy; however they are a very important part of a balanced diet for the following reasons o It aids digestion and promotes bowel action, removing waste products from the body o It helps to control the digestion of nutrients and the way nutrients are processed o It adds bulk to the diet, reducing the feeling of hunger and the desire to eat Functions of Carbohydrates in the Body - Energy; provides the body with most of its energy. They provide fuel for muscular exercise; both voluntary and involuntary. Sufficient supply of carbohydrates ensures ‘protein sparing action’. When there are sufficient carbohydrates in the diet, they rather than the proteins are burnt for fuel thus leaving the proteins for tissue building and repair When the diet lacks carbohydrates, the body can draw for a day or two on its stores of glycogen but when the supply is exhausted, the body used its fat or its tissue proteins for heat or energy To prevent this, the daily diet must contain a regular supply of carbohydrates however in excess will cause obesity - Dietary fibre; are unavailable carbohydrates (i.e. those not brocken down by digestive enzymes) give bulk to the faeces - Storage; Glucose in excess of energy requirements can be a. Converted into glycogen and - Helps the body use other nutrients - Regulates body processes - They act as a protective and detoxifying substance in the liver Cooking Effect on Starch
- 6. Uncooked starch is not digestible Foods containing starch have cells with starch granules, covered with a cellulose wall which breaks down when heated or made moist. When browned as with the crust of bread, toast, roast potatoes, the starch forms dextrins which tastes sweeter. On heating with water or milk, starch granules swell and absorb liquid thus thickening the product (thickened gravy or cornflour sauce). This thickening process is known as gelatinization of starch. Proteins Proteins differ from carbohydrates because they contain nitrogen in addition to oxygen, hydrogen and carbon while others contain sulphur, iron and phosphorous. These elements combine to form 22 amino acids eight of which are essential for growth and repair. Proteins are very important to the body as they are the major part of the cells that actually form the body. It is essential that we have a good supply of proteins in our diet as it is needed for the growth of the body and repair of body tissues. Proteins is composed of different amino acids i.e. proteins of cheese is different from the proteins of meat because the number and arrangement of the acids are not the same. A certain number of amino acids is essential to the body and must be provided by food. Proteins containing essential amino acids in the correct proportion are said to be of high biological value and must be included in the food we eat. They include (Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, Valine, Histidine (essential for Infants) while the other 8 can be produced in the human body and are known as non essential amino acids and they include (Alanine, Arginine, Aspargine, Aspartic acid,
- 7. Cysteine (may occur in the form of Cystine), Glutamic acid, Glycine, Ornithine, Proline, (may occur in the form of Hydroxyproline), Serine, Tyrosine) There are two kinds of proteins namely: - - Animal proteins – found in meat, game, poultry, cheese; myosin, collagen (meat, poultry and fish), albumin, ovovitellin (eggs) casein (milk and cheese) - Vegetable protein – found mainly in the seeds of vegetables. The proportion of proteins in green and root vegetables is small. pulses (beans, peas, lentils), polished cereals (rice), ground nuts, peanuts, green vegetables, soya beans nuts contain most proteins while the grain of cereals i.e. wheat has a useful amount because of the large quantity eaten. During digestion, protein is split into amino acids which are then absorbed into the blood stream and used for building body tissues, provide some heat and energy to the body. Main Functions of Proteins in the body o Growth (to build and repair body tissues) – Cells make up our bodies. As we grow from birth into adulthood, our bodies change and develop. To make new cells, our bodies need proteins o Repair – The life span of cells range from about a week to a few months. Throughout our lives, our bodies need to replace cells as they die. Cells also become damaged if we get injured and we need proteins to replace the dead cells with new ones o To carry our bodily functions – Throughout life our bodies perform millions of tasks. This is happening every second of our lives in our thoughts, actions and in the functions required to stay alive. These are controlled by types of protein called enzymes and hormones. o To form anti bodies to fight infection
- 8. o A secondary source of energy – Any excess protein in our body is converted into carbohydrate or fat. It cannot be stored for use at a later time. Protein is referred to as a secondary source of energy because its main function is not as a source of energy. Proteins vary in effectiveness depending on their amino acid content. Those which both maintain life and support growth are called complete proteins. Proteins which maintain life but do not support growth are called partially incomplete proteins while proteins which do not maintain life are known as incomplete proteins Effect of Cooking Proteins Overheating or cooking by dry heat reduces the nutritive value of proteins by destroying essential amino acids. When heated, various proteins coagulate or set at different temperatures causing the shrinkage particularly noticeable when grilling or roasting meat Moderately cooked protein is easiest to digest; i.e. a lightly cooked egg is more easily digested than a raw or hardboiled egg Cooking in water (poaching, steaming or boiling) increases the digestability of some proteins thereby enhances their nutritive value. Some amino acids become more available through preparation and cooking i.e. when soya beans and wheat are ground into flour Metabolism of Proteins Approximately 15-20% of human body is composed of proteins and exist in the following forms: - 1/3 found in muscles, 1/5 in bone and cartilage Proteins are present in every cells and are essential component of enzymes, hormones, body secretion and blood
- 9. A diet that does not provide sufficient calories from carbohydrates will lead to metabolism of valuable proteins to provide the needed energy. Protein Deficiency Early signs are fatigue and weakness, Severe protein malnutrition results in stunted growth and lack of muscled development in children while in adults it leads to a decrease in muscle protein as tissue protein is broken down to provide necessary proteins for amino acids for body metabolism. - Kwashiorkor; a protein deficiency occurs in small or just weaned children due to inadequate supply of proteins. A condition characterized by: - o Swelling on the ankles, wrist, face and loss of hair color o Retardation of growth o Weight loss o Enlargement of the liver and stomach - Marasmus occurs in children primarily fed on starchy foods . It is a condition characterized by: - o Muscle waste o Swollen limbs Fats Like carbohydrates, fats contain only carbon, hydrogen and oxygen in different proportions. Fats differ from carbohydrates in that they contain fatty acids i.e. butyric acid in butter, stearic acid in beef suet, oleic acids inn most oils. The food value of the various kinds of fat is similar although some animal fats contain Vitamin A and D Fats have many functions in the body and are naturally present in many of the foods we eat. Fats come from animals, fish, vegetables, cereals, nuts and seeds and may be referred to as saturated or unsaturated. Saturated fats are usually
- 10. found in animal products whereas unsaturated fats are usually associated with oily fish, vegetables, seeds and nuts Two main groups of fats include animal and vegetable fats Fats can also be divided into - Solid Fat and Fats can be obtained from the following foods (fats - butter, margarine, oil; meat; cheese, milk, flour, cereals, eggs, fish - Oils (fat which is liquid at room temperature) Types of Solid Fat Description Butter An important source of energy and contains water soluble vitamins A & D. It gives a delicious flavor in cakes and sauces although if overheated when fried, it burns and turns brown Margarine Made from either animal fat or vegetable fat and contains vitamins A & D which are added during the manufacturing process Margarine is cheaper than butter and often can be substituted for it Lard Is fat made directly from pork; It is expensive but is often preferred to other fats for cooking Leaf lard has a mild flavor and is of the highest grade of pork fat and so more expensive than lover grades Bladder lard is another grade of pig fat. It is the dripping from bacon and other cuts of pork and is excellent for seasoning. Sometimes it is used as shortening Suet Is harder than lard and is made from the fat ox or sheep. Deer suet is a little harder than mutton suet and has
- 11. a delicious flavor Suet may be used in both puddings and pastries to give extra flavor Cooking Fat Are made from oils which have hydrogen added to them to give the desired texture and flavor These fats are sometimes known as hydrogenated fats Dripping Comes from roast meat. The fat drips off into the cooking and hardens as it cools however it should be strained before use Drippings varies in taste according to the meat from which it comes Poultry Fat Are rendered (melted down) and strained before using in soups, sauces and baking. They have a strong flavor Vegetarian Fats Are made from vegetable oils, some are purified and hydrogenated to give a white, solid fat The air which is incorporated in them gives a creamy texture The fat can be used for pastry or cake making Some margarine is made entirely from vegetable oils and is good for vegetarians Types of Oils Description Cotton Seed Obtained from pressing cotton seeds and refining the extracted oil The dark color and disagreeable odour and flavor of the curds are removed during the refining process The refined oil is used in salad dressings and for cooking Corn Oil Is produced when corn starch and corn syrup are
- 12. manufactured; the germ of the corn kernel is ground and pressed to produce oil The oil is refined to improve the colour and flavor It is used for salad dressings and for cooking Palm Oil Is extracted from the fruit of the oil palm. It is dark reddish oil and is excellent for frying Olive Oil Is extracted from ripe olives then filtered Olive oil is expensive but it has excellent flavor for both cooking and salad dressings Groundnut (peanut) Oil is pressed from groundnuts and the oil is allowed to settle, filtered and then refined Used for both salads and cooking oil Functions of Fat in the Body The body can produce energy from fats in greater quantities than carbohydrates (sugars and starches) (Is a concentrated source of energy) Fat under the skin acts as an insulin layer and prevents heat loss from the body (They help keep our body temperature stable) Certain fats also provide minerals Provides protection for the vital organs of the body found mostly in the chest and stomach area. Some organs i.e. kidneys have a thick layer of fat surrounding them to protect them from impact and other potential damage (Fats around organs like kidney and heart helps to protect them from physical injury) Fats accommodate the absorption of the fat soluble vitamins (A,D, E, K) Essential fatty acids (linoleic acid (n-6) and alphalinoleic acid (n-3) are important for maintaining the function and integrity of cell membranes The n-3 series of PUFA are needed for the development and function of the brain and retina of the eye
- 13. The n-3 PUFA may also be involved in preventing blood clots while increased intake have been shown to reduce the risk of heart attack. Uses of Fats in Food Production Flavoring Greasing cooking vessels Pastries cakes and biscuits In emulsions Frying Metabolism of Fat To be absorbed in the body, fats have to be broken down into fatty acids so they can be absorbed in the body. In excess, they are stored into the body as adipose tissues for later use. Fat Spoilage Fat which has spoilt is said to be rancid. Some fats are more susceptible than others i.e. butter and margarine should be covered and stored under refrigeration. Liquid cooking fats do not need refrigeration Vitamins The word ‘vitamin’ comes from the Latin word meaning life. They are found in all living tissues and are essential substances for maintaining life Vitamins are chemical substances which are vital for life and if a diet is deficient in them, ill health results. The body requires approximately 13 vitamins to function properly. In comparison to carbohydrates, fats, proteins; vitamins forms a much smaller structural part within the foods we eat. They are a group of complex organic compounds required by the body for the maintenance of health. They are not usually synthesized in the body and are therefore essential in the diet and are present in foods in small amounts Functions of Vitamins
- 14. Vitamins are essential for the human body and performs the following functions: - - They assist in the regulation of body processes i.e. control the functions of body cells - They promote growth and repair of damaged body tissues - Protect the body against diseases and resist infection - Assist in the formation of healthy offspring - Assist in curing certain diseases Major Groupings of Vitamins Fat soluble vitamins comprises of; A, D, E and K Will dissolve in fats and oils but not in water Vitamin A and D can be stored in the body, in the liver In extreme circumstances it is possible to have an excessive intake of these vitamins leading to high levels in the body and a condition known as ‘hypervitaminosis’ Quantities of vitamins A and D are measured in micrograms (µg) Water soluble vitamins includes; B1 (thiamin), riboflavin, niacin and Vitamin C (Ascobic Acid) The vitamins of the B group and vitamin C will dissolve in water but not in fats. Since they are water soluble, they are not stored in the body, any excess is excreted in the urine The quantities of the three main B vitamins (thiamine, riboflavin and niacin) and vitamin C are measured in milligrams (mg) Other vitamins that plays an important part in the diet includes; B6, B12 Cyanocobalamin Pantothenic Acid Folic Acid Biotin Choline
- 15. Inositol Vitamins A and D are stored in the body if they are not needed immediately however water soluble vitamins are not stored so they must be supplied daily Functions of Vitamin A To keep the skin and mucous membranes healthy and resistant to infection They protect against night blindness Vitamins their Uses and Deficiency Vitamin Uses Deficiency Sources Vitamin A (Retinol) Essential for: Growth and metabolism of all body cells Adequate vision in reduced light Formation of teeth and bones, Important for the health of the outer skin tissues and mucous membranes of the body Appreciable amounts are found in the blood Serious deficiency of Vitamin A is first indicated by an inflammation of the membranes of the eye Night blindness ( a condition in which eyes fail to adjust properly when going from light to dark (an indication of lack of vitamin A in the diet) Reduces the rate of growth in children Affects health of the Supplied in two different substances Animal source which is practically colorless; fish liver oils, whole milk, butter, eggs, liver Carotene from plants and has an intense orange, yellow, red, dark green colour
- 16. Acts as an antioxidant in body tissues removing free radicals skin and resistance to infection lowered due to the poor condition of the mucus lining of the respiratory tract Vitamin D Help the body absorb calcium Help build strong bones and teeth Essential for the absorption and utilization of calcium by the body resulting into strong bones and teeth Causes poor bone structure and may result to a condition known as rickets Need for vitamins is greatest during childhood Found in fish liver oils especially in cod- liver oil Small amounts in milk, cream, eggs, butter and liver Develops best when the body is exposed to the direct rays of the sun (sometimes called sunshine vitamins) Vitamin E (Tocopherols) Little is known about vitamin E however it is believed to have some influence on reproduction Is a natural antioxidant In vegetable oils it helps to reduce Deficiency does not normally occur in human though it has occurred in premature babies fed on an infant formulae deficient in vitamin E It has occurred in some people unable Richest source is wheat germ, vegetable oils, nuts, margarine and egg yolk Meat (liver), egg york Butter, nuts, leafy vegetables All sorts of grain,
- 17. rancidity by preventing the oxidation of unsaturated fatty acids May also play a part in protecting ascorbic acid against oxidation in fruits and vegetables They protect lipids especially polyunsaturated fats (PUFA) against free radical damage to absorb and utilize vitamin adequately. These people develop nervous system problems which improved when they were given suitable vitamin E treatment vegetables oils and fruits Vitamin K (also known as Anti- haemorrhagi c vitamin) Helps to control the clotting of blood Aids normal liver functioning Must be provided regularly in the diet Rarely seen because the vitamin is synthesized by bacteria present in the intestines as well as presence in a normal diet Babies particularly if they are premature have low levels in their bodies Found in different kinds of green leafy vegetables and a variety of foods Vitamin B1 (Thiamin / Aneurine) It main function is its role in the digestion and use of carbohydrates by Deficiency leads to partial oxidation of glucose leading to production of pyruvic Lean meat, eggs, whole grain Enriched brown bread and cereals
- 18. the body It encourages and promotes growth in children It stimulate appetite and aid digestion It prevents neuritis (an illness of the nerves) It helps prevent tiredness and keeps nerves healthy Help maintain the nervous tissue Involved in the oxidation of nutrients and the release of energy in the body acid in blood causing muscular weakness, palpitations of the heart and degeneration of the nerves; main symptoms of beriberi Green leafy vegetables, millet and sorghum Nuts, legumes oatmeal and Some fruits B2 (Riboflavin) Allows the body to obtain energy from fats and amino acids Promote growth at all ages Prevent cracks and sores in the skin i.e. corners of the mouth, Prevent the tongue from becoming sore Persistent cracks at the corners of the mouth and lips Lack of B2 over a long period of time results into loss of weight Premature aging May cause dim vision and even cataracts Mainly offal, milk and cheese Eggs, lean meat, whole grain Green leafy vegetables Cereals, fish, rice, Some fruits Yeast extracts or tablets
- 19. Speeds the oxidation of foods and is an important factor in maintaining general good health B2 in conjunction with protein and phosphoric acid forms enzymes which are important to all body tissues Niacin Help maintain the health of the skin, digestive tract and nervous system Promote growth in children Niacin and nicotinic acid is necessary for effective metabolism of carbohydrates Rough skin and reddish rash (dermatitis) Abnormal functioning both of nerve tissues of the gastro intestinal tract (diarrhea) and of the general nerve tissue (depression) – all of which are symptoms of the disease pallegra Palellegra is common in areas where corn or cereals are the major food and where very little if any milk and vegetables are eaten Fish, liver, kidneys and brains Citrus fruits, milk Whole grain cereals, Millet, sorghum Lean meat, Yeast extracts, tablets
- 20. Vitamin C (Ascobic acid) Encourage growth in children Protect mouth and gums from infection Aids in the healing of wounds and severe burns Prevents bleeding gums and slight haemorrhages beneath the skin Help the body to resist infection It maintains capillary strength Causes scurvy (an illness which affects the skin, gums and cause general weakness) Severe deficiency or prolonged absence, teeth becomes loose, joints stiffen and pains occur in the arms and legs Raw fruits and vegetables better sources than cooked or processed ones though modern processing techniques retain a fairly high percentage Excellent sources are all citrus fruits, tomatoes, dark green leaves (broccoli, raw cabbage, parsley lettuce), fruit juices Strawberries, green paper Potatoes, black currants Melons, pumpkins Water Effects of Heat on Vitamins Vitamin A
- 21. Stable under ordinary cooking and food preservation processes. It is not destroyed by light or heat and remains unharmed during storage periods of moderate lengths. Dried foods however may lose considerable amounts of Vitamins A when the food is oxidized. Frozen foods retain most of their vitamin A Vitamin D Resistant to the effect of heat and oxidation and is not always destroyed by ordinary methods of cooking Vitamin C Easily destroyed by oxidation and cooking unless green vegetables are fresh or cooked for a very short time as possible and eaten immediately, most of the vitamin will be lost In order to retain as much of vitamin C as possible while cooking, the conservative method of cooking (using a little water as possible) is best Vitamin E It is destroyed if the fat associated with it becomes rancid Water Water is essential for life. It is a necessity in the body for survival and only second to oxygen. All living organisms contain water; the human body is about 65%water. The body of an adult man contains about 40litres of water. About 15litres are present in the extracellular fluid (3litres in the blood plasma and 12litres in the fluid tissue). The remaining 25litresmake up the intracellular fluids i.e. the fluid found within the cells. Therefore a person can survive without food for several weeks but can live without water for only a few days. Water is essential since it provides a medium in which nutrients, enzymes and other chemical substances can be dispersed and in which the chemical reactions necessary for maintaining life can take place. Nutrients are carried to cells and waste products are transported from the cells by blood plasma which is 90% water.
- 22. Waste products are removed from the blood by the kidneys and excreted in the urine. Water Balance The normal functioning of the body involves a continuous loss of water. Water cannot be stored in the body and therefore a regular intake is essential. Water is taken into the body in foods and drinks mostly absorbed into the body from the large intestines. Some absorption also take place in the stomach and small intestines. Water is formed within the body by chemical reactions when nutrients are oxidized in the cells in order to release energy, carbon dioxide and water are formed i.e. oxidation of 100g glucose produces 60ml of water. The body inevitably loses about 1.5litres of water daily while the kidneys must form at least 600ml of urine in order to get rid of toxic waste products Water is also lost by evaporation from the surface of the body and as water vapour in expired air and a small quantity through faeces. Amount of water taken into the body is determined mainly by habit and custom, it is also regulated by thirst (a sensation that arises as a result of the concentration of sodium in the blood caused by a depletion of water. The kidneys control the output of water from the body, the body cannot store water and any excess passes into the urine. Not only is water a component of all foods, but it contributes significantly to the physical differences among foods and to the changes that foods undergo Sources of Water - Drinks of all kinds - Foods such as fruits and vegetables, meat, eggs
- 23. - Combustion or oxidation: When fats, carbohydrates and proteins are used for energy, a certain amount of water (metabolic water) is produced within the body Functions of Water in the Body Water is required for: - - Regulation of body temperatures by evaporation of perspiration - All body fluids - Digestion - Absorption - Metabolism - Excretion - Secretion - Assist the body in removing waste products; it is important that waste products are removed from the body otherwise it could lead to release of toxins (poison) which could lead to organ damage and or sickness - Control body temperatures; Water helps control body temperatures through sweating, when our bodies get hot or overheated, water is released through our pores thus bringing body temperatures down to a more comfortable level - Transport oxygen and nutrients around the body; nutrients, enzymes and hormones are dissolved in water allowing nutrients to be transported to the many cells around the body A means of transport in the body for example materials are carried to cells and waste products are carried away in blood plasma - Supply minerals directly to the body; water contains minerals naturally although the amounts of minerals can differ according to the origin of the water - Acts as a lubricant; water helps lubricate certain areas of the body particularly the eyes and eyelids, internal organs i.e. small intestines have
- 24. fluids around them allowing them to glide over each other easily without harm. Water also ensures that our joints are flexible allowing for free and easy movement and keeps all air passages moist - A suitable medium in which substances i.e. enzymes and nutrients can be dispersed - A suitable medium for the chemical reactions needed to maintain life Mineral Elements Minerals unlike proteins, carbohydrates and fats are inorganic substances which are present in many foods although they do not provide energy. There are 19 mineral elements, most of which are required by the body in diet through in very small quantities to enable the body function properly. The body has at certain times at greater demand for certain mineral elements and there is a danger then of a deficiency in the diet. The most important minerals needed by the body are; calcium, iron, phosphorous, sodium, iodine, potassium, and trace elements include fluorine, sulpher, zinc, magnesium, copper, aluminium, cobolt and manganese. Calcium, iron, and iodine are those most likely to be deficient while Potassium, magnesium, sulfur and copper Minerals are present in a vast range of foods and forms a tiny structural part within the foods we eat. They have many functions in the body. Functions of Minerals in the Body - Minerals and bones and teeth; minerals found in our bones and teeth includes calcium, magnesium, phosphorous and fluorine - Minerals and bodily function; we need minerals to help control actions like energy release, digestion, excretion and circulation in the body - Minerals and the levels of fluids held in the body; the body is approximately 60-65% water. Minerals are very important for controlling the level of fluids in the body - To build and regulate the body processes
- 25. - They carry impulses along the nerves and are important in the construction of muscles, digestion of food and natural elimination of waste materials - To maintain good health - To heal and protect against diseases Minerals, their Uses and Deficiency Apart from carbon, hydrogen, and oxygen (the main elements that make up proteins, fats and carbohydrates) the body requires at least 20 other elements for a variety of reasons. These are called mineral elements and they are required for: - Body building Control of body processes e.g. transmission of nerve impulses They form an essential part of body fluids Some mineral elements are required in relatively large amounts and they include; calcium, iron, phosphorous, potassium, sulpher, chlorine, sodium, magnesium Others are required in minute amounts and are known as trace elements and they include; iodine, copper, manganese, fluorine, combalt, nickel, zinc, chromium, selenium NB: Most trace elements are supplied by a wide variety of foods and the body is unlikely to be deficient in them thus the discuss below are of mineral elements of greatest importance Mineral s Elemen ts Functions Deficiency Sources Calciu m With phosphorous, it combines to make calcium phosphate which is the chief If the diet lacks calcium, the body makes an effort to maintain the calcium Milk is the best source Cheese, bread eggs
- 26. material that gives hardness to bones and teeth during childhood, adolescences and even in old age Required for part of the complex mechanism which helps in the clotting of blood after injury Required for maintenance of bones and teeth once formed Required for the correct functioning of muscles and nerves to react normally The absorption of calcium and phosphorous and the mineralization of bones and teeth is dependent on vitamin D content in the blood plasma by robbing bones and teeth Continual loss of bone mass can lead to osteoporosis (means the bones becomes, weak, brittle and break easily) Children bones and teeth are not mineralized properly and are improperly formed. The leg bone may bend under the weight of the body (rickets) In adults strength of bones and teeth is not maintained result in osteomalacia (adult rickes) Muscles and nerves do not function correctly leading to a condition known as tetany (the muscles contract rigidly and the patient has convulsions) NB: too much calcium in the body can be dangerous All green vegetables, nuts cereals, whole grain cereals Meat - It is found in green leafy vegetables but may be unavailable to the body because cellulose (which the body cannot digest) affect calcium absorption - It is found in whole grain cereals however it may combine with phytic acid which makes it unavailable to the body, fish
- 27. and fatal when stored in organs i.e. kidney Excess intake of vitamin D absorbs calcium in excessive amounts can result in deaths Iron Unlike many other minerals, it is stored in small amounts in the liver, spleen and bone marrow which is used during periods of illness or haemorrhage but should not be relied upon to replace the daily supply It is a component of haemoglobin, the substance which gives red blood cells their colour thus vital for the development and functioning of haemoglobin (red matter of the blood) Haemoglobin is required to transport oxygen around the body to every cell for the production of energy and the maintenance of all cell Reduces the ability of haemoglobin to carry oxygen to the blood cells causing shortness of breath, lack of appetite, fatigue and slowing of body functions Serious deficiency results in anaemia Haemoglobin is not made properly thus insufficient oxygen is carried around the body leading to fatigue, weakness and a pale complexion In severe cases can lead to a condition known as iron deficiency anaemia General health is affected as cells cannot function properly Liver is the best source Meat and offal, eggs Green vegetables (water cress and parsley) Pulses, raisins, almonds, Oatmeal, millet, sorghum, whole meal flour, bread, Cocoa, chocolate, black treacle, prunes, carrots, peanuts, butter NB: iron in ferrous form is easier to absorb than in ferric form - Iron from plant
- 28. functions Particularly important for lactating, expectant and adolescent girls foods (grains, leafy vegetables and soya protein) may not be absorbed in the body due to the presence of phytic acids - Vitamin C increases iron absorption especially from plant foods (it changes iron from the ferric to ferrous form - Eggs is a good source of iron but the iron is poorly absorbed by humans thus presence of Vitamin C rich foods should be eaten with eggs whenever possible Phosph orous Build and strengthen bones and teeth (in Deficiency is not known to occur in Liver, kidney, eggs, cheese,
- 29. conjunction with calcium and vitamin D Controls the structure of the brain cells and nerves It is essential for the production of energy in the body Forms part of many proteins and is often used as an additive in manufactured foods Essential for every living cells (both plants and animals) Important in certain metabolic processes i.e. chemical reactions with proteins fats and carbohydrates in providing energy and in releasing necessary nutrients for growth and repair of the body With calcium (as calcium phosphate) phosphorous is necessary for normal nerve responses, the construction of muscles, humans Bread, milk, fish, wholemeal flour Cereals (corn, sorghum, millet and rice, legumes All dairy products are good sources NB: Vegetables are not good sources
- 30. the maintenance of blood neutrality and Combined with potassium, phosphorous helps to develop soft tissue and nervous tissue Sodium Helps body fluids do their functions To stimulate the nerves and activate the muscles There is seldom lack of sodium in normal diet as it is used in the preparation of food and is added to cooked food Sodium is lost by the body through perspiration thus a shortage may occur when taking strenuous exercise in excessive heat Results in listlessness and cramp Can cause poor appetite and loss of weight Too much sodium in the body may be harmful to those with high blood pressure Ordinary table salt (common source) Sea foods Salted meat and fish Bread, butter, margarine Sodium , chloride and potassi um Are required to main the correct concentration of the body fluids Chloride is also required for the production of hydrochloric acid in the gastric juice of the Salt tables are issued to some workers in hot climates if they are unused to long periods in heat Sodium and chloride are necessary in hot Usually eaten as sodium chloride or potassium chloride in food Are also added as salts to foods e.g. bacon,
- 31. stomach In food production Sodium chloride is added to many manufactured foods (savoury snacks) Forms part of monosodium glutamate (MSG) and is used as flavor enhancer Sodium bicarbonate and sodium nitrite are also used as food additives climates where they are lost in sweat yeast extracts, fish, cheese Meat, fish Iodine Regulates the thyroid gland (in the neck) which controls the development of the body Regulate body processes Needed for the production of triiodothyronine (T3) and thyroxine (T4) hormones necessary for the maintenance of metabolic rate, cellular metabolism and the integrity of the connective tissue It is an essential component of the Those lacking iodine in the diet are likely to develop goiter (swelling on the front of the neck due to enlargement of the thyroid gland (goiter) Enlargement of the thyroid glands results into lowered metabolism NB: Due to the addition of potassium iodine to table salt, incidences of goiter has declined Sea foods Vegetables (spinach) grown near salt water Iodized table salt Sea salts, water, salmon, ocean fish, butter, milk Foods grown in iodine-rich soil
- 32. thyroid hormone (thyroxine) In the featus, iodine is needed for the development of the nervous system during the first trimester of pregnancy Fluorin e Helps in the formation of strong bones and teeth Helps in strengthening teeth against decay (prevents dental decay or caries) It is thought to combine with the protective enamel coating of the teeth making them more resistant to attack by the acid produced by bacteria in the mouth NB: Fluorine is widely, but unevenly distributed among foods Excess intake can be harmful; it causes mottling of teeth (dark brown spots appearing on the teeth) Sometimes added to water lacking natural fluorine (fluoridicated water) or Added to toothpaste to prevent dental decay Tea Sea water fish Magnes ium Others are required in minute amounts and are known as trace elements and they include; iodine, copper, manganese, fluorine, combalt, nickel, zinc, chromium, selenium Zinc Seleniu m Chromi
- 33. um NB: Most trace elements are supplied by a wide variety of foods and the body is unlikely to be deficient in them thus the discuss below are of mineral elements of greatest importance Nickel Combal t Copper Mangan ese Dietary Fibre These are unavailable carbohydrates; we cannot digest dietary fibre directly like other foods although it will soften through cooking. It is found in plants, vegetables, whole grains, nuts, seeds and legumes. There are two types of fibre which are classified as - Soluble fibre - Insoluble fibre Soluble fibre swells in water to form a gel like substance that slows digestion and helps to control the release the release of glucose into the blood stream. It also binds with cholesterol in the gastrointestinal tract so reducing cholesterol levels They are mainly found in fruits and vegetables and grains i.e. oats Insoluble fibre is the most tough, indigestible fibre such as the skin of fruits and vegetables and the outer parts of seeds, wheat bran and brown rice. Insoluble fire increases faecal weight, so assist in the travel of waste which prevents constipation When eaten, dietary fibre is broken down mechanically by our teeth and swallowed but it is not broken down any further beyond this stage. They promote the removal of wastes from the body and
- 34. Gives a feeling of being ‘full’. It satisfies our hunger and Reduces the likelihood of overeating. Many recent findings recommend that we should reduce the amount of sugar, fat and salt in our diets and increase the quantities of dietary fibre. All dietary fibre comes from vegetables, fruits and cereals. Animal products contain no dietary fibre thus amounts can be increased in our diets through: - - Eating whole meal or granary bread - Use whole meal flour in place of white flour - Eat whole grain cereal products or bran enriched cereals - Eat whole meal pasta and whole grain rice - Eat plenty of fruit and vegetables - Eat plenty of pulses and lentils Portion Sizes Over the last 20 years, led by a global food market from the USA, portion sizes have increased steadily. Research indicate that the more food people have in front of them, the more they will eat; especially those with weight problems It is especially hard to understand why people with weight problems choose larger portions (is it because of memories to do with food shortage or mere greed?) Large portion sizes needs to be overcome in order to maintain energy balance; this is achieved through; - Behaviour training and - Use of smaller plates Portion size is an important concept for anyone involved in preparing, serving and consuming foods.
- 35. Portion size in the food pyramid do not always match the serving sizes found on food labels since the purpose of the food pyramid is not the same as the purpose of nutrition labeling In many cases portion sizes are similar on labels and in the food guide, especially when expressed as household measures What is Portion Size? Portion Size - is the amount of food placed on ones plate or the amount of food you put on your plate. It also means controlling the size or quantity of food to be served to each customer Serving – it a specific amount of food defined by common measurements such as cups or table spoons The amount of food allowed depends on the following three considerations: - The type of customer or establishment (size of portion served for those working in heavy industry will different from that of females undertaking clerical duties while a restaurant offering a three course table d’hote menu for £25 including a salmon, the size of the portion will naturally be smaller than in a luxury restaurant charging £17.50 for the salmon on an a la carte menu The quality of the food (better quality food usually yields a greater number of portions than poor quality foods as it is difficult to get the required number of portions and also leads to time and labour wastage as well as loss of money The buying price of the food (should correspond to the quality of food meaning a good price should mean good quality thus a good yield and therefore help to establish a sound portion control. On the other hand inefficient buying by paying higher price for food of indifferent quality will
- 36. make it difficult to get a fair number of portions thus the selling price necessary to make the required profit will be too high and customer satisfaction can be affected. Why do we over eat? There are two brain systems that govern our food choices; these are: - Limbic System - It is concerned with our subconscious and emotional state - It only takes into consideration what is happening now and does not weigh future consequences - It outweighs analytic system Analytic System - It is the conscious awareness and rational thought - It considers future implications - Rational thoughts is typically overruled by the limbic system Internal Cues - Satiety - Emotional hunger External Cues - Food advertised everywhere in the media - Hidden cues - Good selling tactics Tactics for Healthy Eating Food placements (keep foods in high sugar and fat out of sight, fruits and vegetables in sight and healthy food items at eye level) Plate size (use smaller eating utensils i.e. plates, bowls and cups, use smaller serving utensils when dishing out food, use restaurant meal on a separate plate than the one the food is served on
- 37. Food storage (store leftovers in individually-sized containers, buy snack foods in single serving sizes) Pre-meals (eat a light salad or drink a glass of water before eating meals as this will help to give a sense of satiety sooner) The key to health eating - Variety (dairy products, fruits, vegetables, meat and poultry, fish, legumes, oils and nuts, starch, cereals) - Moderation (today we eat 2-4 times the portion our parents and ancestors ate) - Energy balance (consider energy in and energy out) Why do we gain weight? Energy balance vs - Physical activity - Genetics - Psychology Food and Behavior - Portion distortion - Value for money food packages (bigger portions at home (we eat 2-4 times more – 200 calories more / day – 10kg / year - Increase of size in restaurant and fast food portions (2-3 times) 49-133 extra calories from each food portion - How fast do we eat Portion Sizes - Have also increased Physical Activity - Reduced hours of physical activity (walking, use of cars and motorbikes, elevators) Positive energy balance can lead to obesity Health risks - CVD - Type 2 (diabetes) - Hypertension
- 38. - Gastro intestinal diseases - Some forms of cancers - Respiratory problems - Eating disorders - Myoskeletal diseases Food Labels – the amount of information on food labels varies but all food labels must contain at least o The name of the food o A list of ingredients o The net contents or net weight (the quantity of the food without packaging in English and metric units o The name and place of business of the manufacturer, packer or distributor o Nutrition information is also required for most foods o All ingredients must be listed on the label and identified by their common names so that consumers can identify the presence of 8 major food allergens (eggs, fish, milk, peanuts, shellfish, soybeans, tree nuts and wheat o The ingredient that is present in the largest amount, by weight must be listed first. Other ingredients follow in descending order of weight Nutrition facts – Designed to reflect the amounts people actually eat provided in familiar units Kilocalories – kcal per serving lists the total kcal in one serving as well as kcal from fat Nutrients – information about some nutrients is required; total fat, sat fat, trans fat, cholesterol, sodium, CHO, dietary fibre, sugars, CHON, Vit A, Vit C, Ca and Fe Recommended Dietary Allowance (RDA)
- 39. The Recommended Dietary Allowance or RDA (sometimes referred to as the "Recommended Daily Intake") is defined as "the average daily dietary intake level that is sufficient to meet the nutrient requirements of nearly all (approximately 98%) healthy individuals". Is the average daily amount of nutrients considered adequate to meet the known nutrient needs of practically all healthy people; a goal for dietary intake by individuals The average amount of nutrients which should be provided per head in a group of people if the needs of practically all members of the group are to be met RDAs provide guidelines for recommended nutritional intakes for various groups within the population Present average nutritional requirements only; not everyone within a specific population group needs an identical nutritional intake RDAs are estimates of the nutrients that healthy people should consume RDAs only provides estimates of nutritional requirement for selected nutrients and not all nutrients RDAs should be met by consuming a variety of foods Knowledge about nutrition is constantly evolving thus RDAs are periodically revised RDAs are recommendations for each nutrient taken into consideration however this does not take into consideration the variation that occurs between healthy individuals Uses of RDAs It has been used to assess the diets of groups; Individuals use them to judge the adequacy of their own diets Agencies use them to set dietary goals for communities and the nation Can be used as a reference point in food labeling i.e. nutritional food labeling
- 40. Manufacturers use RDAs as a basis for determining the percentage of daily allowances being provided in specified portion sizes by their products Food Composition Tables Adequate nutrition is one of the pillars of public health. Before developing and implementing effective intervention programmes to improve nutrition at the population level, it is important to know the nutritional situation of the target group. Food composition tables contain more complete values for several nutrients; they include: - Dietary fibre Saturated, monounsaturated fat and polyunsaturated fat Vitamin B6 Vitamin E, Folate Magnesium and zinc Food composition tables include a wide variety of foods from all food groups; it is updated yearly to reflect the current food patterns. The nutritional content of food varies depending on: - - Origin - Climate / season - Soil - The grind or cut size - Method - Duration of preparation - Amounts of food served Food Triangles / Pyramid Has been around since 1992 It’s a hierarchy of food groups in a person’s diet that helps put the dietary guidelines into action It’s not a rigid prescription but simply a general guide that lets people choose the right food with the right amount
- 41. It ranks the food groups according to the amounts to be consumed from the most, which is situated at the base of the pyramid to the least which is located at the apex of the pyramid The Food Pyramid was designed to convey the principles of; Variety – The pyramid is divided into 4 levels and presents 5 food groups Proportionality and Balance – The differences in the areas allotted for the food groups and their location in the pyramid indicate the relative proportions that must be eaten Moderation – Also conveyed by the areas and location of the food group; the recommendation is to ‘just eat enough’ rather than restrict it Indicates the relationship between good nutrition and health and a guide to a well balanced diet A food pyramid is a pyramid shaped guide of health foods divided into sections to show the recommended intake for each food group Types of Food Pyramids/ Food Triangles and MyPlate GO, Glow and Grow Foods Fats, Oils and Sweets (Use Sparingly Are the go foods, contains food with sugar and fat Milk, Yogurt and Cheese Group (2-3) Servings Meat, Poultry, Fish, Dry Beans, Eggs and Nuts Group (2- 3) servings They build and repair the body. They belong to the grow foods Vegetable Group (3-5 Serving) Fruit Group (2-4) Serving Are the vitamin and mineral rich foods i.e. green leafy vegetables. They belong to the grow foods Are the fruits and are rich in minerals
- 42. and vitamins They belong to the grow foods Bread, Cereals, Rice and Pasta Groups, Root crops, Noodles (6-11 Serving) Contains energy and heat giving foods They are composed of grow foods that are rich in carbohydrates and that are starchy The Food Pyramid The Orange Food Group This represents Grains (any food made from wheat, rice, oats, cornmeal, barley or another cereal grain is a grain product The Green Food Group This represents Vegetables (Any vegetable or 100% vegetable juices counts as a member of the vegetable group; Broccoli, carrots, corn, tomatoes The Red Food Group This represents fruits (Any fruit of 100% fruit juice counts as part of the fruit group; Apples, blueberries, grapes, oranges The Blue Group This represents Milk. All fluid milk products and many foods made from milk are a part of this food group; White milk, chocolate milk, chedder cheese, cottage cheese The Purple Food Group This represents Meat and Beans. All foods made from meat, poultry, fish, dry beans, or peas, eggs, nuts, and seeds are considered part of this group
- 43. The Food Plate (MyPlate) MyPlate illustrates the five food groups that are the building blocks for a healthy diet using a familiar image – a place setting for a meal. Before you eat, think about what goes on your plate or in your cup or bowl
- 44. The Food Guide Pyramid was the model for healthy eating in the United States. However, the USDA, the agency in charge of nutrition, has switched to a new symbol: a colorful plate — called MyPlate — with some of the same messages and aims to promote the following nutritional practices for a healthy living; Eating a variety of foods. Eating less of some foods and more of others. The difference and similarity between a Food Pyramid and Myplate The pyramid has six vertical stripes to represent the five food groups plus oils while the plate features four sections (vegetables, fruits, grains, and protein) plus a side order of dairy in blue. The big message is that fruits and vegetables take up half the plate, with the vegetable portion being a little bigger than the fruit section. And just like the pyramid where stripes were different in widths, the plate has been divided so that the grain section is bigger than the protein section. Why? Because nutrition experts recommend you eat more vegetables than fruit and more grains than protein foods. The divided plate also aims to discourage super-big portions, which can cause weight gain. Myplate design incorporates seven key dietary messages; Enjoy your food, but eat less Avoid oversized portions Make half your plate fruits and vegetables Drink water instead of sugary drinks Make at least half your grains whole grains Switch to fat-free or low-fat (1 percent) milk Compare sodium in foods like soup, bread, and frozen meals - and choose the foods with lower numbers.
- 45. Experts argued the now-defunct pyramid lumped all types of foods in its design - including unhealthy ones at the top of the pyramid; This made it hard to tell which foods were better choices.