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July 02, 2012

A Healthy DietTopics covered:

• Nutrients needed by the body• How the body uses different nutrients• The nutrient content of different foods• A balanced diet• Malnutrition• A plan for a healthy diet

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Starter:

• No breakfast• Eat sweets on the way to school• Eat chocolate and Inca cola at break• Have fries and hamburger for lunch• Eat more sweets in afternoon• Avoid green vegetables in evening meal• Drink mainly pop such as cola

Diet 1

• Eat cereal or toast for breakfast• Eat fruit at break• Have a variety of foods for lunch, such as vegetables, rice or pasta.• Eat more fruit in the afternoon• Eat green vegetables in evening meal• Drink juices or water

Diet 2

• Write a description of what you eat during a typical day• Compare your pattern with the two diets below• Which diet does yours match more closely?• From what you already know, try to explain which diet shown is

healthier

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Nutrients - a review

Are chemicals needed by the body to keep it in good shape

• Carbohydrates• Fats• Proteins• Vitamins• Minerals

(also, the body needs about 70% water, and fibre is also needed)

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Carbohydrates

Made from the following elements; carbon, hydrogen, oxygen

= a sugar molecule, containing C, H and O

The most common sugar is glucoseGlucose will form long chains such as starch

Glucose in plants forms chains called cellulose

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Fats (lipids)

Made from lots of carbon and hydrogen Has some oxygen

There are two basic types; solid fats in animals, and liquid oils in plants

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Proteins

Made from carbon, hydrogen, oxygen and nitrogen

C, H, O and N form amino acidsSometimes, sulphur is present

= amino acid

Amino acids join together to form protein molecules

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Vitamins

Needed in small amountsAt first they were given alphabetical names, later chemical names

Minerals

We need 20 different minerals, some in large amounts such as calcium. some are needed in small amounts and are called trace elements

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What does our body do with these nutrients?

Read the descriptions for each type of nutrient and then match the description to the word

Fibre ProteinsMinerals

I contain cellulose from plant cell walls. I am undigestible and allow the food to be pushed through the intestines.

I am used for building structures inside cells. I am needed for growth and repair. Some of us that speed up reactions are called enzymes

We make bones and teeth strong. Others help blood to take up oxygen properly.

Fats Carbohydrates

Water Vitamins

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I help cell membranes to form properly. I also provide energy and also insulate, keeping the body warm.

We help in many tasks, such as helping the eyes to work better or stopping scurvy or allowing bones to take up calcium.

I provide energy for the body and can be released quickly.

I am something very important. You could only live a few days without me! I also help you cool down!

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Malnutrition

If certain nutrients are missing from the diet then malnutrition will occur.

1. A person can be well fed but lack a certain nutrient2. The person may be starving

This falls into two broad catergories:

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A healthy diet

What things are needed for a diet to be considered 'healthy'?

A healthy, balanced diet will contain the right amounts of nutrients and energy to sustain healthy growth and repair.

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Fats

Carbohydrates

Proteins

Fibre, Vitamins and minerals

A Healthy diet

More

Less

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Foods and their nutrient content

Objectives:

• Know what nutrients foods contain• Know how to test for nutrients

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Group the following foods for the nutrient contained

Foods and their nutrient content

Protein Carbohydrate

Fat

Starter

7­up

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How do we know what nutrients are in food?

We know what to eat, but how do we know?

Food testing

Nutrient Test

Protein Biuret's reagent

Carbohydrate (starch) Iodine solution

Carbohydrate (glucose) Benedict's solution

Fat Ethanol

In the last activity, you were asked to place the foods into groups for just one nutrient. Foods contain more than one type of nutrient.

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July 02, 2012

Protein - Biuret's reagent

Blue solution Lilac solution

If protein is present, Biuret's reagent will turn lilac

- ve +ve

Carbohydrate (starch) - iodine solution

If starch is present, Iodine will turn Dark blue/purple

Orange solution Dark blue/ purple

+ve- ve

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July 02, 2012

Carbohydrate (Glucose) - Benedict's solution

If reducing sugar is present, Benedict's solution will change colour

0 1 2 3 4least most

Fat (lipid) - Ethanol

If fat is present, ethanol will form a cloudy solution

Clear ethanol Cloudy ethanol

ethanol and fat ethanol and fat

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July 02, 2012

Food testing

You are going to carry out a series of tests on food to find out what nutrients they contain.Follow the instructions and record your data in a suitable table.

Method:

• Take a sample of food • Test the food for protein, starch, sugar and fat• Record the results in the table• Repeat for the other foods available

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Food Test Observation Meaning

Fish

Protein

Starch

Glucose

Fat

Results:

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Plenary:

The following diagram is called a Venn diagram. Use this to group the food into three main food groups, placing sugar and starch together.

Protein Fat

Carbohydrate

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Food Protein Starch Glucose Fat

Fish

Cheese

Milk

Egg

Butter

Cracker

Bread

Fruit

Ham

7 up

Results: Overview sheet

Homework:

Use the information from this lesson to revise for a test on food tests. You will need to be able to explain the test and what the results mean.

e.g. 1. What is the test for starch?2. a food was tested for starch and the iodine solution

turned black. What does this result mean?

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Look at the following people and decide what types of food they will need to eat in their diet:

Extension activity

Eskimo Athlete

BabyOld age pensioner

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Teenager

Body builder

Officeworker

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Homework

You are a chef who is going to make a menu for a 4- day school field trip for students. The trip will involve a lot of walking and sports activities.

The menu will need to have • breakfast • lunch • dinner

It will need to be balanced and contain all the nutrients needed.

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