NUTRITION The study of food, its composition, the amounts needed by the body and its effects on the body © PDST Home Economics DEFINITIONS Food: any substance, solid or liquid, that contains nutrients. Nutrients: substances that can be digested and used by the body. Elements: All nutrients are made up of elements. They are simple substances that cannot be broken down into anything simpler. Diet: the selection of food each person eats Balanced diet: contains all the nutrients in the correct amount for the needs of the body. RDA: Recommended dietary allowance GDA: Guideline daily amount Nutrients There are 6 nutrients Proteins Fats / Lipids Carbohydrates Mineral elements Vitamins Water Nutrients Macronutrients: needed in large amounts by the body i.e. protein, fat and carbohydrate. Micronutrients: Needed in small amounts by the body i.e. vitamins, minerals Nutrients Composition: the elements that make up the nutrients. Classification: dividing things into groups or classes. Sources: foods that supply a large amount of a nutrient. Functions: Uses of nutrients in the body Protein - Composition Made up of the elements: Carbon Hydrogen Oxygen Nitrogen Protein is the only nutrient with nitrogen which is needed for growth The elements join to form Amino Acids The amino acids link together in long chains called Proteins Protein - Composition Protein - Classification There are 2 classes of protein 1. HBV protein (High Biological Value)/ First class protein / Animal protein. 2. LBV protein (Low Biological Value ) / Second class protein / Plant protein. Both classes of protein are needed in the diet Protein - Sources Animal protein: meat, poultry, fish, eggs, cheese, yoghurt, milk. Plant protein: Lentils, Beans, Peas, nuts, cereals Plant protein foods contain: Less saturated fat More fibre Cheaper to produce Protein - Sources Protein - Functions The growth of all body cells For repair of worn or damaged cells To make hormones, enzymes and antibodies in the body Protein - functions Protein – RDA and Energy value RDA for protein is 1g per day per Kg of body weight. 1 gram of protein can release 4 kilocalories or 17 kilojoules of energy Test on Protein 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Atoms of which elements make up protein? What’s special about Nitrogen? Name the small units that form proteins Name the 2 classes of protein List 5 food sources for each class Give 2 functions for protein What are the effects of protein deficiency Are proteins micro or macro nutrients? How much protein do we need per day? What is the energy value of 1 gram of protein? Lipids (fats & oils)- Composition Lipids are called fats when solid at room temperature and oils when they are liquid at room temperature. Made of 3 elements: Carbon Hydrogen Oxygen The elements make units called glycerol and fatty acids Each glycerol joins to 3 fatty acids to form a lipid Lipids - structure Lipids - Classification There are 2 classes of lipids 1. Saturated lipids: animal fats, solid at room temperature. 2.Unsaturated lipids: plant and fish oils, liquid at room temperature Lipids - Sources 1. Saturated fats are found in: butter, suet, lard, meat, cheese, eggs, milk, yoghurt. 2. Unsaturated fats are found in: fish, nuts, seeds, cereals, soya beans, olives, avocado pears, some margarines, cooking oils. Saturated fat sources Unsaturated fat sources Lipids - Function Releases heat and energy for the body Insulates the body Protects delicate organs e.g. kidneys Source of fat soluble vitamins A, D, E, K Delays hunger Adds flavour to foods Functions of fat Overeating Lipids Overweight or obesity Saturated fats raise blood cholesterol. This causes high blood pressure, strokes and heart disease Benefits of saturated lipids Help reduce cholesterol Omega 3 and omega 6 fatty acids reduce risk of heart disease and improve brain function. They are found in oily fish, seeds and nuts Carbohydrates - Composition Made of 3 elements: Carbon Hydrogen Oxygen The elements form single sugar units e.g. glucose The sugar units link up to form other carbohydrates Carbohydrates-Classification There are 3 classes of carbohydrates Sugars Starches Cellulose (fibre, roughage) Carbohydrates - Sources 1. Sugars are found in: fruit, honey, table sugar, cakes, biscuits, sweets, fizzy drinks, jam 2. Starches are found in: bread, potato, pasta, rice 3. Cellulose is found in: Fruit, vegetables, wholecereals, seeds, nuts, beans, brown bread, brown rice, high fibre breakfast cereals Carbohydrate sources Carbohydrate - functions To supply the body with energy Extra carbohydrate is changed to body fat and stored Cellulose is needed to keep the digestive system healthy and lower cholesterol Cellulose Not digested, just passes through our digestive system unchanged Helps to push food through the intestine and prevent constipation, diverticulosis and cancer of the colon We need to eat 30g of fibre a day to be healthy most people only eat 15g Sugar Sugar is a food we need to eat less of Too much sugar is causing obesity, tooth decay and diabetes A lot of sugar is hidden in foods that don’t really taste sweet especially convenience foods e.g. spaghetti hoops, check label for ingredients Reducing Sugar in your Diet. Replace sugary snacks with healthy fruit , nuts, yoghurt etc. Drink water instead of fizzy drinks Sweeten breakfast cereals with fresh or dried fruit e.g. raisins, banana Check sugar content on food labels and choose low sugar foods Vitamins – (micronutrients) Essential for good health Each vitamin has its own job to do in the body If a vitamin is missing from the diet a deficiency disease can occur Vitamins - Classification 1. Fat –Soluble (dissolve in fat) Vitamins: A,D,E,K. 2. Water – Soluble (dissolve in water) Vitamins:B, C If more of the fat soluble vitamins is eaten than the body needs it is stored in the liver. If an overdose of these vitamins is eaten it causes hypervitaminosis which is harmful to the body. Water soluble vitamins are not stored in the body, if too much is eaten they are removed in the urine. It is therefore important to eat water soluble vitamins every day Fat soluble vitamins Vitamin Sources A Oily fish, cod liver oils Carotene liver/kidney (changed to vitamin A eggs, margarine in the body) e.g. cabbage, spinach D Sunlight oily fish, cod liver oil, tinned salmon/sardines, margarine, butter eggs, Functions Deficiency Eyesight Growth Retarded growth Membranes/linings Night blindness of the body Unhealthy membranes /linings Rickets Healthy bones and teeth Tooth decay Osteoporosis Water Soluble Vitamins Vitamin Sources Function B group Deficiencies Retarded Meat, fish, eggs, cereals, flour, yeast, nuts, pulses, Brown bread, supplements Controls For release of energy from food. a healthy nervous system For growth of healthy foetus during pregnancy Tiredness Beriberi Pellagra Neural Folic acid growth tube diseases Healthy skin & gum C Fruit, esp. blackcurrants, citrus fruit Antioxidant e.g. oranges, strawberries. Veg. esp. Fights infection tomatoes, greens Strengthens blood vessels Aids healing Scurvy Delayed healing Test on Vitamins 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Are vitamins micro or macro nutrients? What are the two classes of vitamins and name the vitamins in each class List (a) 3 sources of vitamin A (b) 2 sources of carotene What is the functions of vitamin D? What happens if you are deficient in Vitamin B? List 4 functions for vitamin C What vitamin can be got from sunshine? Which vitamin prevents scurvy? What is hyper-vitaminosis? Which vitamin works with calcium in the body?