1Seven nutrients
Food gives your body nutrients: substances it needs to work, grow and stay healthy. A balanced diet has the right amount of each of the seven.
nutrientsbalanced diet
Lesson 4.1 notes
What is in food?
Food contains seven kinds of nutrient. Find out what each one does, which foods are rich in it, and how to test a food for it.
2Carbohydrates
Carbohydrates are your main source of energy. Starch, in bread, pasta, rice and potatoes, is a long chain of sugar units. Digestion breaks it into sugar.
carbohydratesstarchsugar
3Lipids
Lipids are fats and oils, found in butter, oil, cheese and nuts. They store energy, keep you warm as a layer under your skin, and cushion your organs.
lipids
4Proteins
Proteins are needed for growth and repair: building new cells and mending damaged ones. Meat, fish, eggs, beans and lentils are rich in protein.
proteinsgrowth and repair
5Vitamins and minerals
You need only tiny amounts of vitamins and minerals. Vitamin C keeps gums and skin healthy, calcium and vitamin D build strong bones and teeth, and iron is needed for red blood cells.
vitaminsminerals
6Fibre and water
Your body can't digest fibre, but it keeps food moving through your gut. Water is needed for every reaction in your cells: about 60% of your body is water.
fibrewater
7Testing foods
Food tests show what a food contains. Iodine turns blue-black with starch, Benedict's turns brick-red with sugar when heated, biuret turns purple with protein, and Sudan III stains fat red.
food tests
Explore: Food test lab
Pick a food and a test, add the reagent, and heat it if the test needs it. Work out which nutrients each food contains.
Common mistake: Your body needs some fat
Fats aren't simply bad for you. They store energy, keep you warm and cushion your organs. Problems come from taking in far more energy than the body uses, for a long time.
Remember
- A balanced diet has the right amounts of seven nutrients: carbohydrates, lipids, proteins, vitamins, minerals, fibre and water.
- Carbohydrates are the main source of energy. Lipids store energy. Proteins are for growth and repair.
- Iodine turns blue-black with starch, Benedict's turns brick-red with sugar when heated, biuret turns purple with protein, and Sudan III stains fat red.
Going further at GCSE