How important is a balanced diet in maintaining good health?
How important is a balanced diet in maintaining good health?
A healthy and well balanced diet is the body's main energy source. In adults, it encourages regeneration and self-healing within the body. In children, it constitutes the building blocks for future health as well as producing energy. A well balanced diet will provide the body with all the essential nutrients it needs. This will be achieved by eating a variety of foods from each food group. A pyramid of food groups is shown in appendix A. There are many different nutrients in each food group; about 50 are known to be essential to human life. Carbohydrates, proteins, minerals, fats and vitamins are the five types of food nutrients. Water can also be classed as a nutrient as it is essential to life. The following assignment aims to describe the functions of the major food nutrients above. The recommended daily allowance (RDA) of nutrients needed for healthy living depends on age, sex, and degree of activity. Larger amounts of certain nutrients are needed throughout life. These are called macronutrients.
Fats are one of the three macronutrients and can be divided into two categories, saturated and unsaturated. Fats are an important part of the diet as they provide a source of energy. It is stored under the skin where it acts as an insulator and also stores certain vitamins. The building blocks of fat are fatty acids and glycerol. The chemical structure of fat is shown in the form of a diagram in appendix B. One glycerol molecule and either one, two or three fatty acid molecules form fat molecules. When glycerol is joined by one fatty acid molecule it is called monoglyceride. Two fatty acid molecules are called diglyceride and three fatty molecules are called triglyceride. The fat is then bonded either as a single or double bond. When a fat has single bonds present, it is said to be saturated. This type of fat is a solid substance at room temperature and the main source is from animals. An example of food that contains saturated fat would be milk, cheese, margarines and man made products like pies, cake and biscuits. The second type of fat is unsaturated. This type of fats is divided into two categories both are liquid at room temperature and are a product of plants with the exception of coconut oil which is a white solid substance and comes under the saturated category. The two unsaturated fatty acids are polyunsaturated and monounsaturated and primarily come from nuts, vegetables and seed sources. Polyunsaturated fats exist when two or more double bonds occur in the fat molecules. These oils would include soybean, corn, sesame, safflower, sunflower and omega oils. Monounsaturated oils include peanut, olive, rapeseed and avocado. This is when one double bond is present and unlike saturated fats are thought to be beneficial to cholesterol levels. Any excess fats in the diet are stored under the skin. Too much saturated fat can lead not only to obesity but heart disease. (Reader's digest, 1991).
Proteins are the second macronutrient needed in the diet. The function of protein is to form building material within the body. There is more protein in the body than any other substance except for water. It is required for the growth and development of every organ in the body. Blood, muscles, heart, brain, skin, hair and nails all depend on protein for good growth. All proteins are built from amino acid molecules, which contain oxygen, hydrogen, carbon and nitrogen atoms. The nitrogen in protein is the body's only source, therefore it is very important. Protein is described as ...
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Proteins are the second macronutrient needed in the diet. The function of protein is to form building material within the body. There is more protein in the body than any other substance except for water. It is required for the growth and development of every organ in the body. Blood, muscles, heart, brain, skin, hair and nails all depend on protein for good growth. All proteins are built from amino acid molecules, which contain oxygen, hydrogen, carbon and nitrogen atoms. The nitrogen in protein is the body's only source, therefore it is very important. Protein is described as either essential or non-essential. Essential amino acids are required for bodily growth but do not occur naturally. Such essential amino acids include: Leucine, Phenylalanine, Isoleucine, Threonine, Lysine, Tryptophon and Methoionine. A healthy diet will provide the body with amino acids. The body will produce these if required and therefore are called non-essential amino acids. Examples of non-essential acids are Alanine, Glycine, Aspartic acid, Serine, Glutamic acid and Tyrosine. Proteins can also be referred to as first and second class. First class contain an adequate amount of all the essential amino acids e.g. meat, fish, eggs, and dairy product and have a high biological value. While second-class protein contain some of the essential amino acids but not enough on their own to promote good health, these have a low biological value. Second class proteins are obtained from vegetables. The RDA for protein will vary from person to person depending on age, activity levels and body size. Protein deficiency can lead to abnormalities in growth and tissue development. Hair, nails and skin will especially be affected and muscle tone will be poor. In adults protein deficiency could result in stamina, mental depression, weakness, poor resistance to infection and slow recovery from illness and disease. In children, severe deficiency can lead to Kwashior, a disease characterised by stunted mental and physical development, loss of hair pigment and a swelling of the joints. (Media company, 2001)
Carbohydrates are the third macronutrient that is needed in a larger quantity. They are important to supply energy for all activities and maintain body temperature. Additionally, they supply indigestible fibrous material to aid digestion and are important in the structure of cells. Carbohydrates are compounds of carbon, hydrogen and oxygen. Most food starts off in the green leaves of plants, where the sun's energy is trapped. This energy is then used to join a molecule of water to a molecule of carbon dioxide to form a simple sugar. Sugar is a simple carbohydrate or monosaccharide. Glucose, fructose, glactose are examples of simple sugars. The reason it is called a simple carbohydrate is because it doesn't take very long for the body to digest it. Starches are complex carbohydrates. They are called this because it takes the body quite a long time to digest them. Two monosaccharides can join to form a disaccharide. Sucrose, maltose and lactose are examples of double sugars. Many monosaccharide units form polysaccharides. See appendix C.
Vitamins are required in smaller amounts than macronutrients, consequently are called micronutrients. They are essential for efficient running of the body. They promote health, have an effect on the ageing process and help prevent disease. They also regulate the building and repairing of cells within the body. Finally, they help to regulate the chemical reactions, which release energy into the cells of the body. Vitamins are divided into two main classes, water soluble and fat-soluble. Vitamins B and C are water-soluble which means that they are dissolvable in fluids within the body. Excess water-soluble vitamins are not stored in the body but are excreted in the urine. Vitamin C is hailed as a miracle cure for everything from depression to the common cold. (Hatfield, 1987). It is needed for the production of collagen, which is the main body protein, maintenance of connective tissues, including tendons, ligaments and cartilage and production of hormones in adrenalin glands. This vitamin can be found in citrus fruits, potatoes and green vegetables. In some cases, deficiency of vitamin C can be the cause of scurvy but only in severe cases. Vitamins that are fat-soluble are A, D, E and K. These are absorbed along with other dietary fats in the small intestine. Fat-soluble vitamins can be stored in bodily cells. Vitamin E is needed to protect cell membrane from damage. It is also needed for the protection of vitamin A and C and for skin repairs. It can be found in vegetable oil, egg yolk, nuts, seeds, peanuts, polyunsaturated margarines, wholegrain and green vegetables. Normally, a good balanced diet will contain all the vitamins you need but some foods do not contain adequate amounts. A table has been produced to show some essential vitamins needed for efficient body function, this is shown in appendix D. Minerals can be found in a wide range of plants and animal foods as well as in water. Serious deficiencies, especially in iron and calcium are more common amongst women than men. Mineral elements are so interrelated that it is difficult to identify their individual task. There are nineteen different mineral elements essential to the body. A table in appendix E shows the function and source of some minerals needed in human development. Others minerals are potassium, sulphur, chlorine, zinc, manganese, copper, iodine and chromium. Minerals are found widely in all foods. There are also smaller amounts of minerals that are essential to the body these are called trace elements and include molybdenum, cobalt, silicon, tin, fluorine, and selenium.
A good diet is central to good health. Many of us are aware of the need to eat a healthy diet for general good health. However, taking steps to improve diet at any time can make significant changes to your long-term health. The word diet really means a combination of several different food types. These food types include grains and pulses, fresh fruit and vegetables, meat, dairy products, fats and oils.
Appendix D.
This table has been produced to show some essential vitamins and their functions.
Vitamin
Function
Source
Deficiency
B1
Nerve cells need it to function normally,
Bran, sunflower seeds, wheat germ
Found in alcoholics, causes depression, fatigue, forgetfulness,
Beriberi
B2
Important for metabolism of protein, fat & carbohydrates
Meat, yeast extracts, milk, eggs, some green vegetables
Found in alcoholics, Poor growth rate, eye problems, sore lips,
B3
Releases energy from carbohydrates, forms fat from carbohydrates
Nuts, yeast, fish, meat
Pellagra is rare in Britain,
B6
Processes amino acids, building blocks of proteins & hormones
Potatoes, bananas, raisin, bran cereals, lentils, liver, turkey & tuna
Rare epilepsy in infants
B12
Nerve cell activity, DNA replication, formation of RBC.
Found in most foods of animal origin, milk, eggs, meat, poultry
C,
ascorbic acid
Formation of connective tissue, heals wounds, keeps skin & bones strong
Soft summer fruits, citrus fruits, vegetables
Fatigue, easy bruising, bleeding gums
Scurvy & rickets
A
Retinol
Beta-carotenes
Good for eyes
Antioxidant
Whole milk, fatty fish, meat, meat products, liver
Apricots, carrots, tomatoes, green vegetables
Dry skin, slow reaction time in retina, dry sore eyes, bacterial conjunctivitis or even death in small children.
D
Developing strong bones & teeth, accelerated healing time for fractures, absorption of calcium in intestine
Fish, liver oils, egg yolks, fortified milk
E
Formation of DNA, RNA & RBC. Acts as antioxidant to inactive free radicals
Fresh nuts, wheat germ, seed oils, liver, eggs, green vegetables
Oxidation of monounsaturated fats resulting in abnormalities in mitochondria
K
Blood clotting
Spinach, cauliflower, cabbage, eggs, milk, liver
Delayed blood clotting time.
Source: class handouts
Appendix E
This table has been produced to show some of the minerals essential for life and their functions.
Mineral
Function
Source
Deficiency
Calcium
Blood clotting. Muscle contraction
Milk, cheese, salad greens, many fortified processed foods
Rickets, weak bones
Magnesium
Helps muscles to relax. Digest meats
Whole grain, nuts, seeds, apples, corn
Fatigue, spasms, muscular weakness.
Phosphorus
Builds bones and teeth. Metabolic processes.
Milk, cheese, nuts, meat, fish and eggs.
Anaemia
Sodium
Transmits nerve pulses. Transports carbon dioxide.
Bananas, citrus and dried fruit. Most food.
][High blood pressure
Iron
Formation of red blood cells
Liver, kidney, heart, eggs, bread, potatoes, green vegetables
Anaemia
Source: class handouts.
References
www.ifst.org/ifstfaq.htm
www.nutrition.org.uk
www.raisingkids.co.uk
www.mrc-hnr.cam.ac.uk
www.poohbah.ndo.co.uk
Class handouts.
The foundry creative media company, 2001.
Frederick C Hatfield, 1987, Ultimate sports nutrition,
Reader's digest, 1991, Eat better live better, Readers digest association Ltd.
Tortora and Grabowski, 2003, Principles of anatomy and physiology, Wiley and sons Inc.
.
Appendix C
This is a diagram to show the structure of carbohydrates
MONOSACCHARIDE one molecule of sugar
DISACCHARIDE two molecules of sugar
POLYSACCARIDE
Many sugars
Julie Barnard Digestive System
Biology
