Food enters the body at the mouth (See ORGANS)

The food that we eat contains lots of good things called nutrients.
Nutrients are useful chemicals needed by our body.

In order to release the nutrients from the food the food needs to be broken down into smaller pieces.
This breaking down of food is called digestion. Digestion is helped by special chemicals called enzymes.

After the food is digested the nutrients are absorbed into the blood

Most digestion takes place in the small intestine.

Unwanted food is removed from the body through the anus.


Summary showing the order of events:


  1. Food is eaten. Food enters the body at the mouth
  2. Food is digested. This is when it gets turned into simple chemicals. Digestion happens mostly in thestomach and intestine
  3. The good things in food (nutrients) are enter the blood.
  4. Any left over solids leave the body through the anus

A diet is the type food we eat.

A balanced diet is selecting sensible foods so we have the right proportion of all the nutrients we need.

A balance diet should contain some of each of the following nutrients

Carbohydrates, Fats, Protein, Vitamins and minerals, Fibre, Water

The table below shows the nutrients that need to be present in a balanced diet

Nutrient Why the nutrient is needed Example foods
Carbohydrate The main source of ENERGY for movement, warmth, cell repair, growth Sugar and starch eg potato, bread,
Fat Energy. Easier for our body to store than carbohydrate. Helps insulate the body from cold. Dairy food (milk, cheese), oils
Protein Body building. eg muscle growth, Repairing and building cells. Meat, soya, cheese
Vitamins Needed in small amounts to keep our body healthyeg Carrot (vit A) Marmite, bread (vit .B), Fresh fruit (vit C) Liver (vit D), Green veg. (vit.E).

Vitamin. C helps stop a disease called scurvy

Fresh fruit and vegetables.
Minerals Needed to keep us healthy eg calcium (strong bones): a lack of calcium can cause rickets.

iron (making blood): a lack of iron can cause anaemia

Milk and cheese (calcium); vegetables (eg spinach is rich in iron)
Dietary fibre* Helps digestion. Helps reduce the risk of heart disease by lowering cholesterol. Brown bread, vegetables, cereal
Water* Water is the main part of all living cells. Our body is 75% water. drinks , fruit

* strictly speaking water and fibre are NOT nutrients.

Fibre helps us to digest food .

We lose water all the time (eg by sweating and breathing out water vapour) and it needs to be replaced. A lack of water will make us ill far quicker than lack of food.

Milk is an important food as it contains most nutrients. It is rich in calcium so is an important food for growing children, however it does not provide a balanced diet. Other foods are needed to provide those nutrients not in milk.


What happens when we run

Our muscles move more and so need more food and oxygen from the blood.

This causes the following changes in our body:

  • Our heart pumps quicker to get the blood to the muscles quicker.
  • We breath faster to transfer more oxygen to the blood
  • We sweat more. As the sweat evaporates it helps cool the body and remove excess heat.