Nutrition: Food & Classes of Food – JSS1 Basic Science Lesson Note (First Term)

Nutrition is the process of taking in food to get energy and maintain life. Food is any substance that, when eaten, is used to maintain life and growth. Food is grouped into seven classes according to the nutrients it contains and the functions it performs: carbohydrates, proteins, fats and oils, vitamins, mineral salts, water and roughages.

Behavioural objectives

By the end of the lesson, students should be able to:

1. define nutrition, food, meal and diet;
2. state the importance of food;
3. name the plant and animal sources of food, with examples;
4. list the classes of food, with their sources and functions;
5. define a balanced diet and state why it is important.

What is nutrition?

Nutrition is the process of taking in food to get energy and maintain life. It is also called feeding in living organisms.

What is food?

Food is any substance that, when eaten, is used to maintain life and growth.

Importance of food

1. To give energy
2. To maintain life
3. It makes us grow
4. To make one stay healthy
5. It helps to build the body and repair worn-out tissues
6. It enables the body to fight diseases

Food items, meal and diet

Food items or foodstuffs are the things that we eat. Examples are rice, beans, yam, garri and groundnut.

Meal: a combination of two or more food items eaten together.

Diet: the meals that we eat every day.

What are the sources of food?

Food items come from two sources:

1. Plants
2. Animals

Plant sources

1. Roots: cassava, carrot, etc.
2. Underground stems: Irish potato, yam, onion, etc.
3. Fruits: palm oil, tomato, guinea corn, maize, etc.
4. Seeds: beans, groundnut, rice, etc.

Animal sources

These include meat, cheese, chicken, eggs, etc.

What are the classes of food?

Food can be grouped according to the nutrients it contains and the functions it performs.

1. Carbohydrates

Sources: rice, cassava, wheat, maize, millet, potato, etc.

Function: It gives us energy.

2. Proteins

Sources: meat, fish, beans, groundnut, milk, egg, melon, etc.

Functions:

1. Repairs worn-out tissues
2. Promotes growth
3. Gives us energy when carbohydrates are lacking in the body

3. Fats and oils

Sources: palm oil, groundnut oil, margarine, butter.

Functions:

1. Act as an insulator and prevent heat loss
2. Provide much energy
3. Form part of the cell membrane
4. Cushion body organs

4. Vitamins

Sources: leafy vegetables, fruits (such as oranges and pawpaw), egg, liver, palm oil.

Functions:

1. Promote a healthy body and growth in children
2. Prevent diseases

5. Mineral salts

Sources: fruit, eggs, milk, dried fish, vegetables.

Function: They aid the formation of good bones, teeth, blood, meat and liver.

6. Water

Sources: rain, spring, river, well.

Functions:

1. It is a component of the blood and flesh
2. It aids digestion

7. Roughages

Source: vegetables.

Function: They make food pass through the digestive system easily.

What are nutrients?

A nutrient is a chemical or food that provides what living things need to live a healthy life and grow well. The different classes of food can also be called nutrients.

What is a balanced diet?

A balanced diet is a diet that contains the correct combination of all the classes of food in the required amounts or proportions.

Importance of a balanced diet

1. It makes us stay healthy
2. It helps to prevent malnutrition
3. It helps to protect the body from diseases

Evaluation

1. What is food?
2. State four reasons why food is important.
3. Mention three sources of carbohydrate.

Assignment

1. List the seven classes of food and give two sources of each class.
2. What is a balanced diet? State two reasons why it is important.