SAINS

BAB 2: CLASSES OF FOOD

Our body depends on food for energy to do work and stay healthy. We also need food to grow. Food can be divided into seven classes.

CLASSES OF FOOD

1- Carbohydrates

2- Proteins

3- Fats

4- Vitamins

5- Minerals

6- Fibre

7- Water

Carbohydrates, proteins, fats, vitamins and minerals are also called nutrients because they contain useful substances required by our body. The process of obtaining and using nutrients from food is called nutrition.

CARBOHYDRATES

Carbohydrates are organic compounds made up of the elements carbon, hydrogen and oxygen. Carbohydrates supply most of energy our body needs. An example of foods that rich in carbohydrates:

- sugar ( found in honey, sugar cane and fruits )

- starches ( rice, bread and potatoes )

- cellulose ( occur in plant cell walls )

Carbohydrate foods

PROTEINS

Proteins are organic compounds containing carbon, hydrogen, oxygen and nitrogen. Sometimes sulphur and phosphorus are also present. A molecule of protein is made up of a large number of subunits called amino acids. Some of these amino acids can be made by our body cells while others must be supplied through the food that we eat.

Proteins are needed for growth and the repair of body tissues. Proteins are required for the formation of enzymes, hormones, haemoglobin and antibodies in our body.

Protein foods

FATS

Fats are compounds of carbon, hydrogen and oxygen. Fats is stored under the skin or around organs in our body. Fat helps to keep us warm and protects organs from damage. Fat helps to transport vitamins A, B, E and K. Fat can store a lot of energy.
Fats consists of smaller units of fatty acids combined with glycerol. Fats are solid while oils are liquid at room temperature. Fats include oil, peanuts, butter and cheese.

VITAMINS

Vitamins are organic compounds needed in small amounts by our body for health and growth. Vitamins are divided into two group: the water-soluble vitamins and the fat-soluble vitamins. The water-soluble vitamins are vitamins B and C. The fats-soluble vitamins are vitamins A, D, E and K. There are types of vitamins:

a) Vitamin A

Source: Carrot, liver, fish liver oil and green vegetables.

Function: For night vision, healthy skin.

b) Vitamin B

Sources: Eggs, milk, meat, yeast and cereals.

Function: Releases energy from carbohydrates, healthy nervous systems, healthy skin and formation of

red blood cells.

c) Vitamin C

Sources: Fresh fruits and vegetables.

Function: Healing of wounds and resistance to diseases.

d) Vitamin D

Sources: Made by our body in sunlight, also found in milk, eggs, fish liver oil.

Function: Strong bones and teeth.

e) Vitamin E

Sources: Vegetable oil, whole grains, nuts and wheatgerm.

Function: May be needed for reproduction, helps to fight against diseases.

f) Vitamin K

Sources: made in the human intestines, also found in egg yolk and green vegetables.

Function: Clotting of blood.

MINERALS

Minerals are inorganic substances needed by our body in small amounts for healthy growth and development. Like vitamins, lack of minerals can cause diseases too. Minerals include prawns, vegetables, cheese, milk and salt. Types of mineral shows below: