© Edco 2011 Lifewise Home Economics for Junior Certificate

© Edco 2011 Lifewise FOOD AND NUTRITION Chapter 1

© 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 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

© Edco 2011 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 There are six types of nutrient: –proteins –vitamins –fats –minerals –carbohydrates –water

© Edco 2011 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 Peas Beans Lentils Nuts Whole cereals Muesli

© Edco 2011 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 Composition of fats

© Edco 2011 Lifewise Sources of fats Saturated fatsUnsaturated fats Mainly from animal sourcesFrom plant and marine sources Butter Meat Milk and cream Cheese Eggs Suet Sunflower oil Olive oil Nuts Seeds Polyunsaturated margarine Fish oils Oily fish

© Edco 2011 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 Composition of carbohydrates

© Edco 2011 Lifewise Sources of carbohydrates SugarsStarchesDietary fibre Fruit (fresh and dried) Milk Cakes, biscuits Soft drinks Jam Ice cream Honey Sugar Cereals Potatoes Root vegetables Pulse vegetables Vegetables Fruit Brown rice Brown bread

© Edco 2011 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 Minerals are essential for a healthy body Minerals that are needed in small amounts are called trace minerals Some important minerals: –Calcium –Iron –Sodium –Phosphorous –Fluorine –Iodine

© Edco 2011 Lifewise Water Sources of water Tap or bottled water Drinks such as milk, tea, coffee Most foods contain water Functions of water Satisfies thirst Helps digestion Helps remove waste from the body Source of fluoride and calcium Part of all body fluids

© Edco 2011 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 1 kcal = 4.2 kJ Energy requirements depend on: Size Age Activity levels Climate Gender Pregnancy

© Edco 2011 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