This project will benefit a student in understanding the concept of a balanced diet. After completion of the project the student must be able to: Explain why diet, especially energy intake, should be related to age, sex, and activity of an individual.
List the principal sources of, and describe the dietary importance of carbohydrates, fats, proteins, vitamins (C and D only), mineral salts (calcium and iron only), fiber (roughage) and water Name the diseases and describe the symptoms resulting from eficiencies of vitamin C (scurvy), vitamin D (rickets), mineral salts calcium (rickets), iron (aneamia). State the effects of malnutrition in relation to starvation, heart diseases, constipation and obesity. A diet which contains all the basic classes of food in the correct amount and proportion is called a balanced diet.
A balanced diet for any individual person depends on their age, sex and life style, activity. Age: Babies and young children have basal metabolic rate and require more energy for growth. So they require more carbohydrates for energy, enough protein for their growth nd sufficient calcium for the proper development of bones and teeth. Sex: Women need less energy than men. The average mass of a woman is smaller than man and men have less fatty tissue in the body. The basal metabolic rate of man is higher than woman. If a man and a woman are involved in identical activities, the man will therefore require more energy from his diet.
So a man needs to include enough carbohydrates in their diet. A pregnant woman requires more iron salts for the formation of haemoglobin in red blood cells sufficient amount of calcium for the growth of babys bones, and more rotein for the formation of babys cells. A pregnant woman has a higher basal metabolic rate than a non-pregnant woman. So they require more carbohydrates. Activity: If a lot of work is to be done, more energy is required. The energy requirement of a manual worker is higher compared to an office worker with a desk bound job.
So a heavy worker requires enough carbohydrates for energy and protein to build up muscles. FOOD GROUPS CARBOHYDRATES Carbohydrates are made up of chemical elements carbon (C), hydrogen (H) and oxygen (O). The ratio of hydrogen atoms to oxygen atoms in a arbohydrate molecule is always 2:1 . Carbohydrates are the cheapest and most readily available source of energy. Carbohydrates can be divided into three classes: 1 . Monosaccharides: simple carbohydrates that are sweet, soluble in water and can be made into crystals. They have simple sugars with the formula C6H1206. Examples of monosaccharides are glucose and fructose. . Disaccharids: double sugars which are sweet, soluble and can be made into crystals with the formula Cl 2H2201 1 . Examples of disaccharides include sucrose (cane sugar), lactose (milk sugar) and maltose (malt sugar of barley). A disaccharide is made by the combination of two monosaccharides with the elimination of one molecule of water. Polysaccharides: are not sweet, not soluble and cannot be made into crystals. Polysaccharides are multiple sugars with the formula (C6H1005) n. It is formed by the combination of many monosaccharides eliminating many molecules of water. E. g. .CeIluIose, starch and glycogen.
MAIN SOURCES Potato cereals rice bread sugar cane yam FUNCTIONS Main source of energy in diet. When glucose is broken down during respiration, energy is released. ENERGY SUPPLY lg carbohydrates release 17kj Of energy. Immediate source Of energy. PROTEINS Proteins contain the elements carbon, hydrogen, oxygen and nitrogen. Often protein contains other elements such as sulfur and phosphorus. Proteins are large, usually insoluble molecules which are built up from simple soluble units known as AMINO ACIDS. Amino acids link together by peptide bonds to form a polypeptide. Polypeptides link together from a protein.
Proteins are large biological molecules, or macromolecules, consisting of one or more long chains of amino acid residues. Proteins perform a vast array of functions within living organisms, including catalyzing metabolic reactions, replicating DNA, responding to stimuli, and transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the nucleotide sequence of their genes, and which usually results in folding of the protein into a specific three- dimensional structure that determines its activity.
MAIN SOURCES Meat fish milk cheese egg wh ite soya beans DIETARY IMPORTANCE (FUNCTIONS) serve as enzymatic catalysts used as transport molecules (hemoglobin transports oxygen) storage molecules (iron is stored in the liver as a complex with the protein erritin) used in movement (proteins are the major component of muscles) needed for mechanical support (skin and bone contain collagen-a fibrous protein) mediate cell responses (rhodopsin is a protein in the eye which is used for vision) antibody proteins are needed for immune protection control of growth and cell differentiation uses proteins (hormones) ENERGY SUPPLY lg protein release 1 7kj of energy. Used when carbohydrates and fats have been used up. LIPIDS Lipids contain the elements carbon, hydrogen and oxygen. However the ratio of hydrogen to oxygen in the lipid molecule is very much higher than 2:1 . Fats are formed by joining of glycerol molecule with 3 fatty acid molecules. They are insoluble in water.
Lipids are a group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E, and K), monoglycerides, diglycerides, triglycerides, phospholipids, and Others. The main biological functions of lipids include storing energy, signaling, and acting as structural components of cell membranes. Lipids have applications in the cosmetic and food industries as well as in nanotechnology. PRINCIPAL SOURCES Butter Margarine Cheese Corn oil Coconut oil palm oil Store energy (for longer usage as compared to carbohydrates) Shock absorber (Protect vital organs in case of shock) Cell membrane structural components Precursors of hormones Insulation – prevent heat loss Aid Vitamin (A, D, E, K) absorption Components of cell membrane, hormones. Myline sheath surrounding nerve fibers.
Stored in adipose tissue beneath the skin and around the kidneys as insulator. ENERGY SUPPLY lg of lipids releases 38 kJ of energy. LJsed after carbohydrate energy store is used up. VITAMINS Vitamins are organic substances needed for chemical reaction in the cells, working in association with enzymes. Vitamins are required by body in small amounts to maintain health. They are not digested or broken down for energy. Apart from vitamin D which is formed by the skin using sun light, vitamins required by the body has to be consumed regularly. Lack of vitamin can cause deficiency diseases. A vitamin is an organic compound and a vital nutrient that an organism requires in limited amounts.
An organic chemical compound (or related set of compounds) is called a vitamin when the organism cannot synthesize the compound in sufficient quantities, and must be obtained through the diet; thus, the term “vitamin” is conditional upon the ircumstances and the particular organism. For example, ascorbic acid (vitamin C) is a vitamin for humans, but not for most other animal organisms. Supplementation is important for the treatment of certain health problems, but there is little evidence of nutritional benefit when used by otherwise healthy people. Name Source Function Deficiency symptoms Vitamin C (Ascorbic acid) Citrus fruits (lemon, orange, green vegetables) For healthy growth and developments of gums and skin repair For formation and maintenance of connective tissues Promote tissue healing Scurvy (bleeding gums, loose teeth, easily bruised)
In extreme cases cause aneamia (lack of blood) and heart failure Vitamin D (Calciferol) Fish liver oil, dairy products (milk, cheese) egg yolk, the action of sun on the skin Helps in absorption of calcium and Phosphorus into the body Important for bone and teeth formation Rickets in children (faulty growth of bones like bowlegs or knock knees) and osteomalcia in adults (easily fractured) MINERALS A mineral salt like calcium is a component of bone tissue and iron as enzymes activators and help in the formation of haemoglobin. Mineral are not organic. Lack of minerals also causes deficiency diseases. A mineral is a naturally occurring substance that is solid and stable at room temperature, representable by a chemical formula, usually a biogenic, and has an ordered atomic structure. It is different from a rock, which can be an aggregate of minerals or non-minerals and does not have a specific chemical composition.
The exact definition Of a mineral is under debate, especially with respect to the requirement a valid species is a biogenic, and to a lesser extent With regard to it having an ordered atomic structure. The study of minerals is called mineralogy. Name Functions Deficiency diseases Calcium (Ca) Milk Soya beans Cereals Sardines For blood clotting Muscle contraption For proper bone and teeth formation Stunted growth Bones become brittle Rickets Osteoporosis in women Iron (Fe) Liver Egg Red meat Spinach Sea food Green leaves For the formation of haemoglobin in the red blood cells Aneamia- deficient quantity of haemoglobin and reduces the oxygen carrying capacity. in severe cases it may lead to coma and death WATER Water makes up about 70% of mammals body weight it is an essential part of the living cytoplasm. eople living in hot climate should drink more water to compensate the loss of water in sweat. We lose water by sweating, urinating and breathing. We have to drink about 6-8 glass of water per day. Although often taken for granted, water is truly an indispensable resource for your body, accounting for roughly 50 to 60 percent of your body weight. If this percentage of water is decreased by 1 percent, your thirst instinct triggers. A 5-percent reduction leads to decreased muscle strength and endurance, and a 20-percent reduction causes death. Many of the processes within your body rely heavily on water, so important that you get enough Of this essential nutrient in your diet.
FUNCTIONS – For transport: it is the main constituent of blood and body fluids and acts as the medium for transport. Nutrients, waste substances, hormones etc. are transported in solution. 2- For chemical reactions: Water serves as a solvent for many chemical reactions of the body. 3- For temperature regulation: Evaporation of water in sweating causes the removal of heat from the body. This prevents overheating of the body. Insufficient water leads to dehydration and death can occur if dehydration is severe. DIETARY FIBER ‘ROUGHAGE Dietary fibers can act by changing the nature of the contents of the astrointestinal tract and by changing how other nutrients and chemicals are absorbed.
Some types of soluble fiber absorb water to become a gelatinous, viscous substance which is fermented by bacteria in the digestive tract. Some types of insoluble fiber have bulking action and are not fermented. Lignin, a major dietary insoluble fiber source, may alter the rate and metabolism of soluble fibers. Other types of insoluble fiber, notably resistant starch, are fully fermented. Some fiber FUNCTIONS Add bulk to the contents of food in the intestine. This helps muscles for peristalsis preventing constipation. Help to retain water, absorb poisons from the gut and soften faeces. Reduces the amount of fat absorption and prevents bowl cancer. Some sources of fiber are in fruit, green vegetables, bread, cereals, and barley.
Lack of fiber causes constipation PROBLEMS OF AN UNBALANCED DIET A person’s diet may be unsuitable for healthy growth for two main reasons: The balance of constitutes is incorrect – leading to malnutrition There is insufficient quantity – leading to starvation MALNUTRITION Malnutrition arises when an organism has an excess of one or more essential utrients or lacks one or more nutrients in the diet. So an unbalanced diet might lead to malnutrition. EFFECTS OF MALNUTRITION constipation heart diseases obesity These are the three most important effects of malnutrition. CONSTIPATION Constipation refers to bowel movements that are infrequent or hard to pass. Constipation is a common cause of painful defecation. Severe constipation includes obstipation (failure to pass stools or gas) and fecal impaction, which can progress to bowel obstruction and become life-threatening. Constipation is a result of insufficient fiber in the diet. Fiber adds bulk to the contents of the intestine and assists in peristaltic movement.
Fiber deficient food move very slowly and as result more water is absorbed from it forming dry hard lumps which get stuck causing constipation. A diet lacking in fiber may, over several years, lead to bowl cancer. HEART DISEASE This can occur when animal fats and cholesterol from deposits called ATHEROMA on the walls of the CORONARY ARTERY, the vessels that carries blood to heart muscle. Atheroma forms a blockage (occlusion) in the artery and restricts blood flow, decreasing oxygen supply to the heart muscle. In evere cases, the artery may become blocked, leading to cardiac arrest (heart attack). Atheroma decreases the bore (diameter) of the arteries and thus can lead to high blood pressure, which increases the risk of heart disease.
OBESITY When a person consumes more food than the body requires for its energy needs, excess food is stored under the skin and around the belly as fat leading to obesity (overt,/eight) Fats provide the greatest amount of energy per units mass-just over twice as much as carbohydrate and proteins. For this reason an individual who eats a diet rich in fats is likely to become obese overweight). The amount of energy contained within the foods they consume is much larger than the energy use up. Obesity is associated with high blood pressure and heart disease. It is often the result of eating too much animal fat, and the heart has to work harder to move the bodys excess weight.
Obesity may also lead to diabetes, stress on joints, and social rejection. STARVATION Starvation is a severe deficiency in caloric energy intake. It is the most extreme form of malnutrition. In humans, prolonged starvation can cause permanent organ damage and eventually, death. The term inanition refers to he symptoms and effects of starvation. According to the World Health Organization, hunger is the single gravest threat to the world’s public health. The WHO also states that malnutrition is by far the biggest contributor to child mortality, present in half of all cases. Under nutrition is a contributory factor in the death of 3. 1 million children under five every year.
Figures on actual starvation are difficult to come by, but according to the Food and Agriculture Organization, the less severe condition of undernourishment currently affects about 842 million people, or about one in eight (12. 5%) eople in the world population. Poverty Poverty is general scarcity or dearth, or the state of one who lacks a certain amount of material possessions or money. Absolute poverty or destitution refers to the deprivation of basic human needs, which commonly includes food, water, sanitation, clothing shelter, health care and education. Relative poverty is defined contextually as economic inequality in the location or society in which people live.
Over population Overpopulation occurs when a population of a species exceeds the carrying capacity of its ecological niche. Overpopulation is a function of the number of ndividuals compared to the relevant resources, such as the water and essential nutrients they need to survive. It can result from an increase in births, a decline in mortality rates, an increase in immigration, or an unsustainable biome and depletion of resources. Drought Drought is an extended period when a region receives a deficiency in its water supply, whether atmospheric, surface or ground water. A drought can last for months or years, or may be declared after as few as 15 days.
Generally, this occurs when a region receives consistently below average precipitation. It can have a substantial impact on the ecosystem and agriculture of the affected region. Although droughts can persist for several years, even a short, intense drought can cause significant damage and harm to the local economy. Prolonged droughts have caused mass migrations and humanitarian crises. The world produces enough food to sustain the current population. However some areas over produce, while other do not produce enough.