Home economics

Lifewise Home Economics for Junior Certificate © Edco 2011 Lifewise Chapter FOOD AND NUTRITION © Edco 2011 Lifewise Functions of food • Food helps the body to grow • Food provides the body with energy and warmth • Food protects the body against disease © Edco 2011 Lifewise Nutrition: important terms • Nutrient – a chemical in food that nourishes • • • • • © Edco 2011 the body, e.g protein Composition – what the nutrient is made of Source – a food that contains the nutrient Function – what the nutrient does in the body Recommended dietary allowance (RDA) – the amount of the nutrient we should eat each day Deficiency disease – ill effects that are caused by lack of the nutrient Lifewise Nutrients • A nutrient is a chemical in food that nourishes the body • Although water is not regarded as a nutrient, it is essential for life © Edco 2011 • There are six types of nutrient: – – – – – – proteins vitamins fats minerals carbohydrates water Lifewise Macronutrients and micronutrients • Proteins, fats and carbohydrates are macronutrients: they are needed in large amounts • Vitamins and minerals are micronutrients: they are needed in small amounts © Edco 2011 Lifewise Proteins • Proteins are made up of amino acids • Amino acids are made up of carbon, oxygen, hydrogen and nitrogen © Edco 2011 Lifewise Classification of proteins Foods containing high biological value protein Foods containing low biological value protein • • • • • • • • • • • • Meat Fish Eggs Milk and dairy produce Soya beans Quorn © Edco 2011 Peas Beans Lentils Nuts Whole cereals Muesli Lifewise Functions of protein • • • • Helps body cells to grow Helps the body repair damaged cells Forms hormones and enzymes Used for heat and energy when there are not enough energy foods in the diet © Edco 2011 Lifewise Fats • Fats are made from fatty acids and glycerol • Each molecule of glycerol is attached to three fatty acids • Glycerol and fatty acids contain carbon, hydrogen, oxygen © Edco 2011 Composition of fats Lifewise Sources of fats Saturated fats Unsaturated fats Mainly from animal sources From plant and marine sources • • • • • • • • • • • • • Butter Meat Milk and cream Cheese Eggs Suet © Edco 2011 Sunflower oil Olive oil Nuts Seeds Polyunsaturated margarine Fish oils Oily fish Lifewise Functions of fats • Provide heat and energy • Contain vitamins A, D, E, K • A layer of fat under the skin insulates the body • Protect delicate organs • Delay the feeling of hunger © Edco 2011 Lifewise Carbohydrates • Made up of simple sugars • Simple sugars join to form starch • Carbohydrates contain carbon, hydrogen and oxygen © Edco 2011 • Composition of carbohydrates Lifewise Sources of carbohydrates Sugars Starches Dietary fibre • • • • • • • • • • • • • • • • Fruit (fresh and dried) Milk Cakes, biscuits Soft drinks Jam Ice cream Honey Sugar © Edco 2011 Cereals Potatoes Root vegetables Pulse vegetables Vegetables Fruit Brown rice Brown bread Lifewise Fibre • Fibre absorbs water and becomes bulky in the intestine • This prevents constipation and other bowel diseases • RDA for fibre: 30g for an average person © Edco 2011 Lifewise Vitamins • Vitamins are needed in small amounts • They are divided into two groups: – Water-soluble: vitamin B group and vitamin C – Fat-soluble: vitamins A, D, E and K © Edco 2011 Lifewise Minerals © Edco 2011 Lifewise Water Sources of water • Tap or bottled water • Drinks such as milk, tea, coffee • Most foods contain water © Edco 2011 Functions of water • Satisfies thirst • Helps digestion • Helps remove waste from the body • Source of fluoride and calcium • Part of all body fluids Lifewise Energy Energy from food • The body’s cells burn food and produce energy This is called oxidation • Energy in food is measured in kilocalories or kilojoules • kcal = 4.2 kJ © Edco 2011 Energy requirements depend on: • • • • • • Size Age Activity levels Climate Gender Pregnancy Lifewise Energy balance • Energy input should be equal to energy output • Extra energy is stored in the body as fat • Too little energy can lead to a person being underweight © Edco 2011 Lifewise