Healthy diet.ppt. for year 8 science or grade 7

year 8 science

1. HEALTHY DIET LIFE PROCESSES

2. LEARNING OBJECTIVE Identify the constituents of a balanced diet for humans as including protein, carbohydrates, fats and oils, water, minerals (limited to calcium and iron) and vitamins (limited to A, C and D), and describe the functions of these nutrients.

3. KEY WORDS Protein, carbohydrate, sugar, fats, oils, minerals, calcium, iron, vitamin, nutrient, constituents, function, balanced diet

4. KEY POINTS A balanced diet contains the correct amount of all food groups. The food groups are: carbohydrates, lipids, proteins, vitamins, minerals, dietary fibre and water. Each food group has its own role to play within a healthy diet.

5. BALANCED DIET To keep healthy, it is vital to eat a balanced diet. This means eating the right amount from different food groups. Too much may cause obesity and too little may cause malnutrition. The World Health Organisation recommends getting at least half of your energy intake from carbohydrates and no more than 30% from fats. The organisation also recommends 400 grams of fruit and vegetables daily.

6. NUTRIENTS Nutrients are essential substances that the body needs. There are different types of nutrient, each with its own purpose:

7. CARBOHYDRATES Carbohydrates provide energy. They are found in bread, potatoes, rice and pasta.

8. FATS AND OILS Lipids (fats and oils) provide energy. Lipid-rich foods include butter and cheese.

9. PROTEINS Proteins provide materials to make new cells and to repair damaged tissues, such as muscles. Beans, eggs, fish, meat and milk are high in protein.

10. VITAMINS Vitamins are vital in many processes. For example, vitamin K helps blood to clot and vitamin C prevents illness. Fruit and vegetables are vitamin-rich.

11. VITAMINS VITAMIN FOODS FUNCTION(S) Vitamin A Cheese, eggs, oily fish Fighting infection, better vision, keeping skin healthy Vitamin C Citrus fruits Healthy skin, blood vessels, bones and cartilage Vitamin D Our body creates this from direct sunlight but it is in oily fish, red meat and egg yolk Helps keep bones, teeth and muscles healthy

12. MINERALS There are 16 essential minerals . These include iron, used to transport oxygen in the blood, and calcium, used in making bones and teeth.

13. WATER Around 70% of human body mass is water. Chemical reactions in cells take place in water and the blood transports substances dissolved in water. Drinking water frequently replaces the water lost in urine, sweat and breathing out.

14. LEARNING OBJECTIVE Understand that carbohydrates and fats can be used as a store of energy in animals, and animals consume food to obtain energy and nutrients.

15. KEY WORDS Carbohydrate Fat Nutrient Energy Store

16. KEY POINTS Carbohydrates are an important source of energy in a healthy diet. Starchy and sugary foods are high in carbohydrates. Athletes eat different types of carbohydrate at different times in their training schedules.

17. How does your body use carbohydrates? Carbohydrates are an important source of energy. They fuel the processes in your body. Carbohydrates are broken down by the body into glucose, which can be absorbed into the bloodstream. Once absorbed, glucose molecules travel in the blood to the body's cells where they are used for respiration. The glucose reacts with oxygen, releasing energy .

18. How does your body use carbohydrates? Starch and sugars are digested differently by the body: Sugary foods and drinks can be quickly broken down to make glucose. This can be quickly absorbed into the bloodstream to provide a short-lasting energy boost. Starch is a long, complex molecule which is harder to break down into glucose. This means that it releases energy more slowly. As such, it is known as a slow-release carbohydrate .

19. Who needs to know about carbohydrates? Athletes need different types of carbohydrate for different situations. Before a short race, an athlete might eat a sweet banana for an ‘energy boost’. Before a long training session, an athlete might eat plenty of starchy pasta for a steady supply of energy .

20. FATS Key points Lipids include fats (solid at room temperature) and oils (liquid at room temperature). Lipids are an important part of a healthy diet. The body uses lipids as an energy store, as insulation and to make cell membranes.

21. FATS Fats - These are solid at room temperature. Butter and cheese are high in fat. Fat is also an important energy store for the body. In addition, the layer of fat under your skin provides insulation and thin layers of fat protect vital organs.

22. FATS I t is important not to each too much fatty or oily food. This is because small amounts of lipid-rich foods can store large amounts of energy. Eating too much fatty or oily food, whilst not getting enough exercise, may cause obesity. Adults and teenagers are advised to eat no more than 70 g of fat per day.