Unit 3 Nutrients in food: Food groups

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2 Unit 3 Nutrients in food: Food groups The main food groups and their function Lesson 6 Living organisms need food to grow and stay healthy. There are 7 life processes that every living thing needs: energy to feed, breathe, move, grow, excrete, sense things and to reproduce. People and animals get their energy from the food they eat. Everything you eat contains nutrients. Nutrients are substances in food that keep your body healthy. Foods can be grouped according to their functions in your body and the main nutrients they supply. Most natural foods contain a mixture of more than one nutrient group. The four main food groups are: Carbohydrates for energy Proteins for growth and repair Fats and oils for storing energy and insulation Vitamins and minerals for building bones and teeth and maintaining a healthy immune system. Carbohydrates Carbohydrates give living organisms energy. Carbohydrates are used by the body to keep it warm and to provide all the energy it needs for growth and movement. Without carbohydrates you will be too tired to walk, run, and dance or even to think. Carbohydrate foods contain sugars and starch. We find sugary carbohydrates in fruits, honey, dried fruits, cold drinks, etc. Sugar gives our body s quick energy. Sugary foods do not have all the important nutrients in them that our bodies need.

3 We find starch in foods such as maize meal, potatoes, rice, bread, pasta and some fruits. Starch releases energy more slowly into our bodies so the energy lasts longer. Starch is the most common form of carbohydrate in our diet. Activity 6 1. Why is it useful to know which foods contain starch? 2. Name one advantage of eating foods that contain starch? 3. Does bread contain starch? Give a reason to support your answer. 4. What substance is used to test for starch? 5. Why is this substance used for a starch investigation? Lesson 7 Proteins Living organisms need proteins to build and repair their bodies and for growth. Proteins also help living things fight sicknesses and they help your immune system fight of infections. Proteins also make up part of your red blood cells, which are responsible for carrying oxygen from the lungs to the rest of your body. Muscles and organs are mostly made up of proteins. Proteins are part of everything in our bodies, such as bones, hair, skin and nails. It is important to get proteins from a variety of foods such as: meat, fish, eggs, nuts, and beans. Eating the right amount of proteins is important to help repair any tissues that are damaged through normal use over the years. Proteins give the body strength and are very important for muscle growth.

4 Activity 7 Draw a table with two columns, in your workbooks. Carbohydrates Proteins Sort the following foods into carbohydrates or proteins: eggs, beans, bread, meat, cool drinks, maize meal, potatoes, nuts, lentils, chicken, fish, pasta, honey, dried fruit, sugar, etc. You can draw examples of the different foods or use pictures from magazines. Lesson 8 Oils and fats Oils and fats give energy to living organisms. Oils and fats give more energy than any other food type. They store energy in the form of body fat. These body fats form protective layers inside the body, to protect the organs and to keep some animals warm. Foods such as nuts, avocado pears and sardines contain healthy oils and fats. Oils are liquid fats made from plants and fish and they provide important nutrients. Eating too much red meat, chocolates, cakes and cooking fat is not healthy as they contain saturated fat which is not a healthy fat. Activity 8 Practical investigation: To test if oils and fats are present. Materials required: brown paper Peanut butter, fried chips, yellow cheese, chocolate, a hamburger patty, an avocado pear Discuss, with your partners, whether you think the following foods contain fat or not. Will these foods leave a fatty stain on the brown paper? Investigation Results record your results

5 Lesson 9 Vitamins and minerals Vitamins and minerals work together with carbohydrates, proteins and fats to help our bodies grow and develop normally. Our bodies need vitamins and minerals to help us build strong teeth and bones, have good eyesight and a healthy immune system. The immune system fights germs and stops us from getting sick. Activity 9 Look at the following tables on vitamins and minerals Important vitamins Vitamin Function Foods that contain the vitamin A Helps you see at night Helps your body fight infection Carrots, pumpkin, butter, liver B Helps make energy, proteins and red Cereals, brown rice, meat, vegetables blood cells, plus many other functions C Helps fight infections Green vegetables, oranges, guavas D Helps makes strong bones Margarine, eggs, our bodies make vitamin D when we are exposed to sunlight. E Protects the skin Spinach and other green leafy vegetables, carrots, avocado pears, butter K Helps to stop bleeding Spinach, broccoli and other dark green vegetables

6 Important minerals Mineral Function Foods that contain the vitamin Calcium Makes teeth and bones strong Dairy foods such as milk, yoghurt, cheese and green leafy vegetables Iron Helps make red blood cell which carry Red meat, green leafy vegetables, oxygen around your body and gives beans you energy. Zinc Helps you grow Meat, fish and poultry REMINDER Bring into class a variety of food labels or packaging (can foods, cereals, pasta, etc.) for lesson 10 and lesson 11 Lesson 10 Food additives Most food that comes in a package such as a tin, bottle, box or sealed plastic packet, is processed food. Most processed or manufactured foods have added salt (sodium) and sugar as well as other food additives such as preservatives, flavourants and colourants. Flavourants and MSG (flavour enhancer) which improve the taste Preservatives (sodium nitrite and sodium nitrate) makes food last longer Colourants makes food look appetising or good enough to eat. Look at the different food packaging labels that were brought into class. Activity 10 What are E numbers? E numbers are codes for chemicals that can be used as food additives. Many food additives have E numbers.

7 E are colourants E are preservatives E are flavourants Tartrazine, a yellow colourant, is also called E102. Look for E numbers on packets of jelly, puddings, sweets and chips. Sulphur dioxide is also called E220. It is a common preservative in fruit juices and dried fruit. Monosodium glutamate (MSG) is a savoury flavourant also known as E621 Lesson 11 Labels on food packaging Activity 11 Labels on food packaging (Choose three different food labels) Aim To read the nutritional information on food labels and to identify the nutrients. Materials You will need (a variety of food labels) packets, tinned food, cereals, pasta, etc. Read the list of ingredients on the food labels for the additives. Questions Look at the labels on the packaged items of food: 1. List the three main food groups of your 3 items that you have selected 2. List the nutrients that are listed for your products. 3. List the food additives for your products.