English Afrikaans

Nutrients in food

Why do I have to eat so many different things - why can't I just eat what I like?
I have heard that people say: 'You are what you eat...' - what does that mean?
What is so bad about sugary sweets - why shouldn't I eat lots of them?
What is the difference between a fat and an oil?

Food groups

Learners must collect the wrappers and packaging material of the food they eat for the activity that follows. Advise them to wash all tins or plastic that still contains food particles to avoid nasty odours and insect infestations in your class!

All living plants and animals need to feed or eat to give them energy to carry out the life processes. Plants make their own food from sunlight, water and carbon dioxide through the process of photosynthesis. Animals cannot make their own food and need to eat plants or other animals to get energy. People also have to eat plant or animal products to get energy to grow and develop.

Classification of food groups

The food we eat can be grouped or classified into different types or groups. We call these food groups. There are a four main food groups and each food group does a different job in the body:

carbohydrates
proteins
fats and oils
vitamins and minerals

Examples of the foods in the food groups; carbohydrates, proteins and fats and oils.

We classify food according to these food groups, although most foods contain a mixture of more than one nutrient group.

Let's look at each food group separately and see why each one is important:

Carbohydrates:
- They are the most important source of energy for the body.
- They store energy for the body.
- Carbohydrates are an important part of the body structure.
- Foods that contain carbohydrates are: pasta, samp, potatoes, cereal, mealie meal, porridge and bread.

Proteins:
- Proteins are the building blocks for our body - they build the body's muscles.
- They also help to repair hurt or broken tissue.
- Proteins can be used as reserve energy if there is a shortage of carbohydrates.
- Some foods that contain proteins are: meat, fish, chicken, eggs, beans, milk and cheese.
- Protein is also found in many plant products: chickpeas, beans, lentils, nuts and soya.

Lipids - fats and oils:
- Fat is stored around organs like the kidneys to protect them from injury.
- Fat is also stored under the skin to insulate us (keep us warm).
- Fat can be used as reserve energy if there is a shortage of carbohydrates.
- Foods that contain fats include: butter, margarine, sardines, cooking oils, nuts, peanut butter and avocado pears.

Vitamins and minerals:
- Vitamins and minerals are essential to the human body and yet we produce very few of them ourselves.
- Many important minerals are contained in the food we eat. Two of the most important are:
  - Sodium that helps to keep the correct balance of water in the body and is found in most food.
  - Calcium that is important for strengthening of bones and teeth. Calcium can be found in fish, green vegetables, milk and cheese.
- Most vitamins are manufactured by plants, so we get vitamins from the food we eat or from vitamin supplements.
- There are specific foods that contain specific vitamins. The table below shows some important vitamins, their natural sources and/or the food that contains them and some of their functions in the human body.

Name of vitamin	Sources	Function
Vitamin A	Egg yolk, liver, deep-yellow and deep-green fruits and vegetables, fish liver oils	Enables the eye to produce a pigment that helps us to see in dim light.
Vitamin B	Brown rice, whole-wheat bread	There are several types of vitamin B and they have many functions, e.g. they are important in the chemical reactions of breathing.
Vitamin C	Citrus fruit, strawberries, tomatoes, peppers	Strengthens the body's immune system by increasing its ability to fight infections.
Vitamin D	Egg yolk, fish liver oils, can be made in the skin when the ultra-violet rays from the sun convert cholesterol in the skin to vitamin D	Helps the absorption of calcium and phosphate. These nutrients are used for the making of strong bones and teeth.

Fruit and vegetables are sources of vitamins.

Classifying food into the different food groups

MATERIALS:

Collect wrappers and packaging material, like boxes and tins, of the foods you eat and bring these to school.

INSTRUCTIONS:

Work in groups of 2 or 3.
Choose the 3 foods that you think are the most healthy to eat from the different wrappers and boxes that you have in your group. Write a reason next to each of these 3 choices why you think they are really healthy.
Locate the LIST OF INGREDIENTS on each food container. You should have at least 10 different containers. (If you have too few, swap with another group when they are finished with theirs.)
Sort the different foods into the major food groups.
Record your work in the table below.

Carbohydrates	Proteins	Lipids	Vitamins and Minerals

Very often food manufacturers add different preservatives, flavourings and colourings, as well as salt and sugar, to make the food look or taste more attractive to their customers. These are called additives.

Read the ingredients on your 10 packaging labels again.
In the first column, write the name of your product.
Tick (✔) under each column if your product has any of these items added to it.
The first one is done as an example.

	Food	Additives
		Salt	Sugar	Others
EXAMPLE	Bread	✔	✔	✔
1
2
3
4
5
6
7
8
9
10

Make a list of the main flavourings that were used in your products.
What preservatives are used most often by the food manufacturers?
Look at the 3 foods you said were the most healthy at the beginning of this activity and why you said they were healthy options.
1. Read their packaging details - which additives do they contain?
2. Do you think these additives make these products healthier or less healthy to eat?
3. After reading the labels do you still think these are the 3 most healthy foods? Explain your answer.
4. Compare the other labels and decide if there are perhaps other healthier foods on your list.

After doing this activity, did you notice a difference between foods which are naturally occurring (such as meat and vegetables) and foods which have been processed?

The natural foods contained a mixture of more than one nutrient group. For example, nuts are a source of protein and fat. Milk is a source of calcium and protein. Vegetables contain many nutrient groups.

The foods which have been processed, or manufactured, often contained additives, such as salt, sugar, preservatives and flavourings.

SUGGESTED PROJECT - If required, teachers can use this opportunity for a small research project on additives and the pros and cons of eating foods with additives.

Let's have a look at some different meals to see if we have all the food groups.

Sorting foods in a meal into the food groups

INSTRUCTIONS:

Below are pictures of five different meals.
Study each meal and classify each food on the plate into one of the food groups (protein, carbohydrates, fats and oils, vitamins and minerals).
Remember, some foods may contain more than one food group.
In the table, write out each food in the meal, and next to it, write the food group it belongs to.

Meal	Food groups

QUESTION:

Which meal do you think is the healthiest? Explain your answer.

In the next chapter we will look more at what makes up a balanced meal.

Food groups:
- foods for energy - carbohydrates
- foods for growth and repair - proteins
- foods for storing energy (in the form of body fats) and providing insulation and protection for nerves and organs - fats and oils
- foods for maintaining a healthy body and immune system - vitamins and minerals
Most natural foods contain a mixture of more than one foor group.
Most processed (manufactured) foods have added salt, sugar, preservatives, flavourings and colourings.

Write the sentence out in full below and fill in the missing words.

Foods are classified into the following food types, carbohydrates ,_____, proteins and _____.

Name 3 reasons why lipids are important in our diet.

Fat is stored around organs for protection. Fat is stored under the skin to insulate us. Fat can be used as reserve energy if there is a shortage of carbohydrates.

List 3 sources of proteins.

Meat, fish, chicken, eggs, beans, milk, cheese (accept any 3 sources of protein).

Why is it necessary to supplement our diets with vitamins?

Allow learners to give their own reasons.

Complete the table below which shows some important vitamins, their natural sources and functions.

Name of vitamin	Sources	Function
Vitamin A		Enables the eye to produce a pigment that helps us to see in dim light
	Brown Rice, whole-wheat bread	There are several types of this vitamin and they have many functions in the chemical reactions of cellular respiration
Vitamin C		Strengthens the body's immune system by increasing its ability to fight infections
Vitamin D	Egg yolks, fish liver oils, can be made in the skin when the ultra-violet rays from the sun convert cholesterol in the skin to vitamin D

Name of vitamin	Sources	Function
Vitamin A	Egg yolk, liver, deep-yellow and deep-green fruits and vegetables, fish liver oils	Enables the eye to produce a pigment that helps us to see in dim light
Vitamin B	Brown Rice, whole-wheat bread	There are several types of this vitamin and they have many functions in the chemical reactions of cellular respiration
Vitamin C	Citrus fruit, strawberries, tomatoes, peppers	Strengthens the body's immune system by increasing its ability to fight infections
Vitamin D	Egg yolks, fish liver oils, can be made in the skin when the ultra-violet rays from the sun convert cholesterol in the skin to vitamin D	Used for the making of strong bones and teeth

What are some of the additives that processed foods contain?

Salt, sugar, preservatives, flavourings, colourings

A vegetarian is someone who does not eat meat. What other foods, besides meat, should they be eating and why?

A vegetarian might not get enough protein. They should eat other sources of proteins such as eggs, beans, cheese and other dairy products and nuts.