Food & diet - IGCSE


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Food & diet - IGCSE

  1. 1. FOOD AND DIET B M Subramanya Swamy M.Sc. B.Ed. CIE Co ordinator & Examination Officer Kanaan Global School Jakarta Indonesia
  2. 2. FOOD AND DIET B M S Swamy Universal School Jakarta
  3. 3. FOOD Source of fuel for the body Eaten in the right amount and types, it leads to good health It serves to : - supply energy - promote body growth and repair of tissues - regulate body functions Carbohydrates, fats and proteins are nutrients that provide energy Vitamins, mineral salts and water are not digested. It is used to regulate body functions Dietary fibre is important in preventing constipation
  4. 4. Carbohydrate Carbohydrates contain compounds of carbon, hydrogen and oxygen in the ratio of 1 : 2 : 1 Carbohydrates Types Sources Function • Provide energy • Converted to glycogen for storage Sugar cane, Excess is stored as fats beetroot, milk Monosaccharide (single/simple sugar) Glucose Fruits and Fructose vegetables Galactose Disaccharide (double/complex sugar) Sucrose Maltose Lactose Polysaccharide Starch Rice, cereal, Used in synthesis of DNA Cellulose bread Glycogen
  5. 5. Fats_________________________ 1. Composed of carbon, hydrogen and oxygen 2. Oils (fatty acids and glycerol) are liquid at room temperature. They have a low melting point. 3. Waxes are solid at room temperature. 4. Fats provide twice as much energy as carbohydrates. They are stored in the body as fats. 5. There are saturated and unsaturated fats.
  6. 6. Fats Saturated Sources Butter Animal fats Unsaturated Fish oil Vegetable oil Function Provide energy Medium for intake of vitamin A, D, E and K Synthesis of cell membrane Insulation layer under skin Protects organs from physical injury
  7. 7. Proteins___________________ ☺ Composed of carbon, hydrogen, oxygen and ☺ ☺ ☺ ☺ nitrogen. May contain sulphur or phosphorus. Protein molecules are composed of large numbers of amino acids linked together by peptide links. Lack of proteins lead to kwashiorkor. Complete proteins come from animal sources. Incomplete proteins come from plant sources.
  8. 8. Proteins Animal/plant Sources Lean meat Fish Human (9 essential Liver and 11 non-essential Milk protein) Cheese Soya beans Cereals Function  Growth of new tissue  Replacement of cell component  Build up body structure like hair and nails  Function of muscles, tendons and ligaments  Formation of enzymes and hormones  Components of antibodies
  9. 9. Fibre______________________ Fibre in the diet consist of carbohydrates, mainly cellulose and lignin They are not digested by the human body Sources Function Fruits, vegetables,  Stimulates peristalsis, whole meal bread moves waste along and cereals intestines  Absorbs water, making wastes softer. Thus preventing constipation
  10. 10. Minerals___________________ ۩ ۩ ۩ ۩ ۩ Inorganic, chemical elements Regulate body processes Not stored in the body (except for iron) Is quickly used or lost Body requires calcium, phosphorous and magnesium more than iodine, iron and zinc
  11. 11. Mineral Sources Function Deficiency Symptoms Calcium Cheese, • Development of milk, oyster, strong bones and green teeth vegetables • Blood clotting • Muscle contraction • Nerve/heart activity • Soft bones • Osteoporosis (adults) • Rickets (children) • Slow blood clotting • Weakness • Wounds heal slowly Iron Egg, lean meat, legume, green leafy vegetables • Anaemia • Paleness of skin • Fatigue • Forms haemoglobin in RBC • Transport oxygen as oxyhaemoglobin
  12. 12. Vitamins_____________________ ♣ Organic compounds, required on small quantities ♣ Water-soluble vitamins (B and C) are not stored in the body. Excess of these vitamins are excreted ♣ Fat-soluble vitamins (ADEK) need not be consumed everyday, it is absorbed by the body and stored in the liver
  13. 13. Vitamins Sources A Fish liver oil, dairy products, green vegetables B1 Function • Healthy growth • Maintenance of skin tissue • Formation of visual pigment in the retina • Promote cell Whole grains, egg, respiration meat • Normal growth Deficiency Symptoms • Poor skin • Night blindness • Lethargy • Retarded growth • Degeneration of nerves and muscles (beri – beri)
  14. 14. • Healthy epithelia • Strong gums • Helps heal wounds • Aids in iron absorption C Fruits (esp. citrus), potatoes, green vegetables (scurvy) • Bleeding gums • Loose teeth • Bleeding under the skin • Slow healing of wounds D Fish liver oil, • Absorption of (rickets) dairy phosphorous and • Mainly in products calcium children • Builds and maintains • Leads to bones and teeth bowlegs and beaded ribs
  15. 15. Water________________________ 1. 2. 3. 4. Makes up about 60 – 70 % of body weight Lost in urine, perspiration and breathing If not replaced, the body gets dehydrated This leads to muscles cramps and weakness in the body
  16. 16. Function of water in the human body Function Transport Mode of action • Main constituent of blood and body fluid • Medium for transport of nutrients, water, hormones, etc • Solvent for chemical reactions Reactions • Hydrolytic reactions during digestion • Constituent of synovial fluids in Lubricants joints and mucus in alimentary canal Homeostasis • Evaporation of water from sweating cools the body. Thus preventing overheating.
  17. 17. World Food Supply There has been a dramatic increase in world population There has not been an increase in natural resources to feed the increasing population Malnutrition is a world wide problem. It takes many forms.
  18. 18. Types of Malnutrition Malnutrition Form Starvation • Insufficient food to supply daily requirements of the individual Eating disorder  Anorexia nervosa • May be genetic or environmental • Constant dieting with rapid weight loss • Psychological condition influenced by fashion trends  Bulimia  Eating too much food, and then getting rid of food by vomiting or use of laxatives Marasmus • General starvation • Both energy and protein are insufficient • Affects children less than 1 year old who have been weaned too early or given poor substitutes for mother’s milk
  19. 19. Kwashiorkor • Children displaced from breast feeding after arrival of new baby • Develops protein deficiency diseases • Body is dwarfed Obesity • Being 20% above ideal weight • May be caused by thyroid problems, or low metabolic rate Overeating saturated • Increases level of cholesterol in the blood • Is deposited on walls of arteries where they harden fats Constipation • May cause clots to form, leading to heart attack and high blood pressure • Difficult bowel movement • Could be caused by lack of exercise, emotional stress, misuse of laxatives, diet low in dietary fibre • May cause vessels in rectum to produce haemorrhoids, resulting piles • Can cause pain and bleeding
  20. 20. Causes of food supply shortage Causes Form Population explosion • World population on the rise • Poverty, starvation and depletion of natural resources also on the rise Famine • Extreme shortage of food • Industrial nations have food surplus • Under-develop nations with no means to pay for the expensive food Drought • Severe climatic change • Extreme crop damage • Destruction of farm animals • Rivers overflow their banks, monsoon rains, tidal waves etc. • Destruction of agricultural lands and crops • Lands destroyed by tidal waves not suitable for farming anymore Flood
  21. 21. Solution to world food supply shortage Solution Form Green revolution New strain of crops to enhance food yields Farming the sea Culturing fish, lobsters, prawn and crabs, and plants like seaweed and algae Genetically modified food Genes altered to improve quality of food Increase shelf life, size, nutrient content Distribution of food World Red Cross organizations supply food surplus to over populated third world countries Farming technique Improve output of farms Use machinery and fertilizers Enriched foods Basic foods with increase in nutrients to improve quality of food Addition of vitamins and minerals Pest control Reduce quantity of food lost during storage or growth Increase land under cultivation Increase food production Use of arid, semi – arid and desert areas with irrigation methods for farming
  22. 22. Diet Balanced diet ♦ Food intake and energy required varies with sex, age and occupation ♦ Good nutrition involves selecting food from the various food groups ♦ Eat grain, vegetables, fruits, dairy protein-rich food, fatty food
  23. 23. Basic food group Food group Grain Sources Whole grain, enriched flour Fruits and vegetables Dark green vegetable, deep yellow vegetable Dairy Milk and milk products Protein-rich Poultry, eggs, red meat, legumes Fats and sweets Candy, pastry, oil, coffee Nutrients Carbohydrates, fibre, vitamin B, iron and protein Carbohydrates, fibre, various vitamins and minerals Main source of calcium, protein, vitamin A, B and B2 Rich in protein, vitamin B, magnesium and zinc Low in nutrient value
  24. 24. Energy A balanced diet supplies all the essential nutrients in the correct proportions Basal metabolic rate (BMR) and physical activity determines the energy to maintain BMR to sustain activities BMR varies by sex, age and state of health of the individual
  25. 25. Energy supplied by the various food types 1 g of food type Energy (kj) Carbohydrate 2.2 Fat 8.5 Protein 7.2
  26. 26. Food Additives Additives  substances added to foods in small quantities for a variety of reasons. Function Flavorings Examples Advantages Disadvantages • Monosodium Glutamate (MSG) (an amino acid) • Salt Improves taste High doses can cause sweating and hyperactivity. • Chocolate flavour Improves taste The sugar in chocolate provides an excellent substrate for growing bacteria which produce acids which can cause tooth decay, also fattening. • Sugar Improves taste Contributes to high blood pressure.
  27. 27. Function Examples Advantages Disadvantages To improve nutritional quality • Lysine is added Enriches poor to flours in places diet where diet is poor. • Vitamin D is added to white flours Colouring Annatto Improves appearance, by replacing colour lost in processing Some people are allergic to annatto Sweeteners Nutrasweet Food can taste sweet without being so fattening Unsuitable for some people. Gives a bitter aftertaste.
  28. 28. Function Examples Advantages Disadvantages Preservatives Vinegar, salt, sugar Reduces bacterial spoilage on ready – made meals. E.g. salad Vitamin content of food declines with storage. Anti-oxidant Sodium ascorbat Stops fat spoiling and becoming rancid in pre – cooked meats Stabilisers Carragheen Stops food texture separating Thickeners Guar gum Gives a thicken consistency and better sensation in the mouth.