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Learning Objective

Learning Objective. To understand the functions of Vitamins in the body. Starter – Fats and oils. Name two dairy products that are available in reduced fat versions . (2 ) Margarine/butter, milk, cheese. Describe visible and invisible fats, and give examples of each. (4)

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Learning Objective

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  1. Learning Objective To understand the functions of Vitamins in the body

  2. Starter – Fats and oils Name two dairy products that are available in reduced fat versions. (2) Margarine/butter, milk, cheese. Describe visible and invisible fats, and give examples of each. (4) Visible fat is when the fat is visible to the eye (easy to detect) e.g. fat on meat, cooking fats such as lard, oil, butter etc. Invisible fats are part of food or when mixed with other ingredients and difficult to detect. This includes products like cakes, pastry and biscuits, also eggs yolks, nuts, seeds etc.

  3. Starter – Fats and oils What is the difference between fats and oils? (2) Fats are solid at room temperature and oils are liquid at room temperature. Should we be eating more saturated or unsaturated fats in our diet? Why? (2) We should be eating more unsaturated fats. Saturated fats come from animals sources and if eaten in excess can cause many illnesses. Unsaturated fats come from plant sources.

  4. Starter – Fats and oils In detail, explain two dangers of eating a diet high in fats & oils(6) Dangers of eating a diet high in fats and oils are people can become overweight (obese), high levels of cholesterol, coronary artery disease, heart disease etc. In detail, explain two dangers of eating a diet low in fats & oils(6) Dangers of eating too little fats and oils in the diet are low body weight (anorexia/bulimia) dry, scaly skin, hair loss, cold intolerance etc.

  5. Vitamins Vitamins are a group of different chemical substances. Vitamins are identified by a letter and also a name. The body requires only small amounts of each vitamin. In general vitamins are needed to regulate maintenance and growth of the body.

  6. Vitamins Vitamins can be classified according to the substances in which they dissolve. There are two groups. Fat-soluble vitamins Vitamins A, D, E and K Water-soluble vitamins Vitamins C and the vitamin-B complex

  7. Fat soluble VitaminsVitamin A (Retinol) Functions of vitamin A (Retinol) • To make a substance called visual purple, which is formed in the retina of the eye to enable it to see in dim light • Keep the mucous membranes in the throat and the digestive, bronchial, and excretory systems moist and free from infection • Maintenance and health of skin • Normal growth of children, particularly the bones and teeth.

  8. Fat soluble VitaminsVitamin A (Retinol) Functions of vitamin A (Retinol) Animal sources RETINOL Plant sources CAROTENE Converted Digestive system RETINOL absorbed Stored in liver

  9. Fat soluble VitaminsVitamin A (Retinol) Sources of vitamin A (Retinol) Vitamin A is found as retinol in animal foods: • Milk, cheese, egg (yolk), butter • Oily fish e.g. Herring, pilchard, sardine • Liver, kidney, cod & halibut-liver oil

  10. Fat soluble VitaminsVitamin A (Retinol) Sources of vitamin A (Retinol) Vitamin A is found as carotene in plant foods: • Carrots, spinach, watercress, parsley, cabbage, prunes, apricots, tomatoes.

  11. Fat soluble VitaminsVitamin A (Retinol) Sources of vitamin A (Retinol) Vitamin A is found as carotene in plant foods: • Carrots, spinach, watercress, parsley, cabbage, prunes, apricots, tomatoes. During digestion, carotene is converted into retinol. Two parts carotene are required to form one part of retinol. Vitamin A is added by law to margarine to ensure people obtain enough.

  12. Fat soluble Vitamins Vitamin A (Retinol) Special requirements • Children need plenty of Vitamin A for growth and development • Expectant and nursing mothers need extra vitamin A for development of the baby and the maintenance of the mother • People who cannot digest and absorb fat well may need to have a vitamin A injection to overcome this.

  13. Fat soluble VitaminsVitamin A (Retinol) Effects of Vitamin A (Retinol) deficiency • The retina does not make the substance visual purple and vision in dim light is impaired=night blindness • In severe cases the structure of the eye deteriorates and can lead to total blindness • The skin becomes dry and infected • Growth of children is effected • Pregnant women can develop a deficiency as the growing baby is provided with any vitamin A that is available in the diet

  14. Fat soluble VitaminsVitamin A (Retinol) Effects of Vitamin A (Retinol) excess Too much vitamin A in the diet is poisonous to the body as it is stored. This can affect the skin and joints, especially in children.

  15. Fat soluble VitaminsVitamin A (Retinol) Effects of heat/cooking/destruction Retinol and carotene are both insoluble in water, and are unaffected by normal temperatures and methods of food preparation.

  16. Fat soluble VitaminsVitamin D (Cholecalciferol) Functions • Formation of bones and teeth • Helps the body absorb the minerals calcium and phosphorus

  17. Fat soluble VitaminsVitamin D (Cholecalciferol) Sources Vitamin D is found in good supplies in the following foods: • Liver • Fish-live oils • Oily fish e.g. Herring, pilchard, sardine It is also found in smaller amounts in the following foods: • Egg yolk • Margarine (added by law) • Milk and dairy products • Sunlight is also an important source of vitamin D. The amount of vitamin D in dairy food products are higher in the summer due to more exposure to the sun. When the body is exposed to UV rays, a substance under the skin (dehydrocholesterol) is converted to cholecalciferol, which is sent for storage in the liver, to be used as required.

  18. Fat soluble VitaminsVitamin D (Cholecalciferol) Ultra Violet light Animal sources (Cholecalciferol) Skin Dehydrocholesterol coverted to Cholecalciferol Digestive system Cholecalciferol Absorbed Calcium Phosphorus Bones Teeth

  19. Fat soluble VitaminsVitamin D (Cholecalciferol) Effects of deficiency • Absorption of calcium and phosphorus is reduced –reduces strength of teeth and bones • Rickets – legs become weak and bend (this mainly affects children) • Osteoporosis – weak and brittle bones • Growth of children can be affected

  20. Fat soluble VitaminsVitamin D (Cholecalciferol) Effects of excess Too much vitamin D in the diet can be dangerous as it results in an excess absorption of calcium into the blood. The extra calcium is deposited in the lungs and kidneys and can cause death.

  21. Fat soluble VitaminsVitamin D (Cholecalciferol) Effects of heat/cooking/food preparation Vitamin D is unaffected by normal cooking temperatures and processes and does not dissolve in water.

  22. Questions • List the functions if vitamins A & D. • List the sources of retinol. • List the sources of carotene. • Why is milk produced in the summer richer in vitamins A & D than winter milk? • Why is margarine a good source of vitamins A & D? • How does ultra violet light help the body to make vitamin D? • Why is too much vitamin D dangerous?

  23. Water soluble vitaminsVitamin B complex • It is called vitamin-B complex due to at least 13 substances exist in this group of vitamins. • The main vitamins in the complex that we will be looking at are: • Thiamin (Vitamin B1) • Riboflavin (Vitamin B2) • Nicotinic acid • Cobalamin (Vitamin B12)

  24. Water soluble vitaminsVitamin B complex The main sources of vitamin-B complex are: • Cereals – especially wholegrain cereal products • Bread, flour, yeast and yeast extracts, beer, wheat germ • All meat – especially pork, ham, bacon, liver, kidney, heart • Eggs • Fish roe • Milk

  25. Water soluble vitaminsVitamin B complex Thiamin (Vitamin B1) Functions • Involved in the metabolic reactions which release energy from carbohydrate • Required for the normal growth of children and the maintenance of general health • Required for the function and maintenance of the nerves

  26. Water soluble vitaminsVitamin B complex Thiamin (Vitamin B1) Requirements • Thiamin cannot be stored in the body, so a daily supply is necessary for all age groups. • Requirements are increased during pregnancy and lactation, and also people who live a very active lifestyle.

  27. Water soluble vitaminsVitamin B complex Thiamin (Vitamin B1) Deficiency A deficiency of thiamin may occur for several reasons, including alcoholism, some digestive disorders and pregnancy (loss of appetite, vomiting) A deficiency may result in the following symptoms: • Depression, irritability, difficulty in concentration, anxiety • Growth issues in children • Nerves become inflamed and painful • Severe deficiency leads to the disease beri-beri-this is when someone becomes so exhausted and loses weight, muscles become weak especially in the legs, ankles and wrists drop.

  28. Water soluble vitaminsVitamin B complex Thiamin (Vitamin B1) Stability in food preparation Thiamin is very soluble in water, and some is destroyed by high temperatures used in cooking.

  29. Water soluble vitaminsVitamin B complex Riboflavin (Vitamin B2) Functions • Essential for normal growth • Required for the release of energy from food, especially amino acids and fat.

  30. Water soluble vitaminsVitamin B complex Riboflavin (Vitamin B2) Requirements Riboflavin can be stored in small amounts in the liver, spleen and kidneys, but a daily supply is required by all ages. Bacteria normally present in the intestine can produce some riboflavin, but not enough to meet all the body’s needs.

  31. Water soluble vitaminsVitamin B complex Riboflavin (Vitamin B2) Deficiency • Failure to grow • Skin condition – dermatitis, and conjunctivitis (disorder of the outer membrane of the eye) • Tongue may swell, mouth and lips becomes sore.

  32. Water soluble vitaminsVitamin B complex Riboflavin (Vitamin B2) Stability Riboflavin is soluble in water, and is destroyed if heated in the presence of an alkali e.g. Bicarbonate of soda. Exposure to light also destroys the vitamin. This is why foods such as milk should be stored in the dark.

  33. Water soluble vitaminsVitamin B complex Nicotinic acid (Vitamin B3) Functions Release of energy from food, especially carbohydrate Requirements A supply of nicotinic acid is required every day and more is needed during pregnancy and lactation.

  34. Water soluble vitaminsVitamin B complex Nicotinic acid (Vitamin B3) Deficiency A deficiency can result in the disease pellagra, which is characterised by the following symptoms: • Dermatitis • Dementia • Diarrhoea

  35. Water soluble vitaminsVitamin B complex Nicotinic acid (Vitamin B3) Stability in food preparation Nicotinic acid is readily soluble in water, but resistant to heat, oxidation and alkali. It is the most stable vitamin in the B complex, in normal cooking processes.

  36. Water soluble vitaminsVitamin B complex Cobalamin (Vitamin B12) Functions It is required for the metabolism of amino-acids as well as other enzyme systems throughout the body.

  37. Water soluble vitaminsVitamin B complex Cobalamin (Vitamin B12) Requirements • Vitamin B12 is produced in the intestines by bacteria, and is only found in useful amounts in animal foods. • Vegans may have an insufficient intake. • More is needed when pregnant and during lactation.

  38. Water soluble vitaminsVitamin B complex Cobalamin (Vitamin B12) Deficiency It can lead to anaemia, in which the red blood cells become enlarged.

  39. Questions • How many vitamins are there in the B complex? • Why do people who live a very active lifestyle require plenty of thiamin? • What are the symptoms of beri-beri and how is it caused? • What effects do cooking processes have on the B vitamins?

  40. Water soluble vitaminsVitamin C (Ascorbic acid) Functions • Required to make connective tissue which binds the body cells together • Assists the absorption of the mineral iron from the small intestine during digestion. • Assists in building of strong teeth and bones • Required for the production of blood and the walls of blood vessels • Required for the building and maintenance of the skin and linings of the digestive system.

  41. Water soluble vitaminsVitamin C (Ascorbic acid) Sources Vitamin C is found mainly in fresh fruits and vegetables. Rich sources Blackcurrants and green peppers Good sources Citrus fruits – oranges, grapefruits, lemons Strawberries Cabbage, spinach Brussels sprouts, broccoli Reasonable sources Bean sprouts, peas Potatoes The amount of vitamin C present in food varies according to the time if year, stage and place of growth, variety of plant and degree of ripeness.

  42. Water soluble vitaminsVitamin C (Ascorbic acid) Requirements A daily amount of vitamin C is required to keep the bodies store ‘topped up’ but it is not a vital requirement every day. Ascorbic acid is stored in the body, mainly in the liver and adrenal glands. As a nation we eat potatoes in large quantities. These make a real contribution to our supplies of vitamin C.

  43. Water soluble vitaminsVitamin C (Ascorbic acid) Deficiency Prolonged deficiency may lead to: • Connective tissue not made or maintenance correctly • Walls of blood vessels weaken and break in places. Blood escapes and appears as small red spots (haemorrhages) under the skin. • General weakness, irritability, pain in muscles and joints. • Gums bleed, teeth loosen.

  44. Water soluble vitaminsVitamin C (Ascorbic acid) Deficiency A severe deficiency leads to a disease called scurvy. Other deficiency symptoms include: • Cuts and wounds fail to heal properly • Scar tissue may weaken and break open • Anaemia because iron is not absorbed properly without vitamin c. It is rare to see cases of scurvy in the UK but some elderly people on low income can show some symptoms –swollen gums and loose teeth.

  45. Water soluble vitaminsVitamin C (Ascorbic acid) Stability in food preparation Heat 50% of vitamin C is lost during cooking of green vegetables. • Avoid peeling vegetables such as potatoes before cooking • Cook as quickly as possible, with the lid on to reduce oxidation • Serve quickly • Over-cooking, reheating and keeping meals warm are all inadvisable

  46. Water soluble vitaminsVitamin C (Ascorbic acid) Stability in food preparation Oxidation Once vegetables and fruit are harvested, the vitamin C content is reduced through oxidation. • Fruits and vegetables should be stored in a cool, dark, dry, ventilated place as warmth speeds up oxidation. • Bad storage results in a 90% loss of vitamin C.

  47. Water soluble vitaminsVitamin C (Ascorbic acid) Stability in food preparation Water Ascorbic acid is highly water-soluble. • Vegetables should not be soaked in water • Cook vegetables in very little water • Use up the cooking water for sauces/soups

  48. Water soluble vitaminsVitamin C (Ascorbic acid) Stability in food preparation Chopping An oxidising enzyme (oxidase) which is present in the cell walls of plants destroys vitamin C. If fruits and vegetables are chopped, grated or bruised, the oxidase is activated. • Chopped foods such as coleslaw should be eaten soon after preparation • Oxidase is destroyed at 85oc, blanching vegetables before freezing them will conserve the ascorbic acid.

  49. Questions • What are the functions of vitamin C? • What is the connection between vitamin C and iron? • How is the amount of vitamin C present in food affected? • What is the effect of cooking processes on vitamin C?

  50. Water soluble vitaminsVitamin C (Ascorbic acid) The effect of heat on Vitamin C experiment. We will all use 50g white cabbage and look at how much vitamin C is lost through a variety of cooking methods. We will investigate: • Uncooked cabbage • Cabbage cooked for 2 minutes in 300ml water • Cabbage cooked for 4 minutes in 300ml water • Cabbage cooked for 6 minutes in 300ml water • Cabbage cooked for 8 minutes in 300ml water • Cabbage steamed for 2 minutes over 300ml water • Cabbage steamed for 4 minutes over 300ml water • Cabbage steamed for 6 minutes over 300ml water • Cabbage steamed for 8 minutes over 300ml water

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