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Red blood cells

8-minute read

Key facts

  • Red blood cells make up just under half of your blood cells.
  • Your red blood cells carry oxygen around your body and take carbon dioxide to your lungs to be exhaled.
  • Your red blood cells are made up of haemoglobin which help it to function.
  • Iron is an important part of haemoglobin that helps to bind oxygen.
  • It's important to get enough iron and other nutrients in your diet to keep your red blood cells healthy.

What are red blood cells?

The red blood cells are also called erythrocytes. They are an important part of your blood, along with other cells, including:

Red blood cells make up just under half of your blood cells. Individual red blood cells are disc shaped.

What are red blood cells made of?

Red blood cells contain a protein called haemoglobin. Haemoglobin carries oxygen in the blood to tissues in your body. Haemoglobin is made of iron. The iron in haemoglobin is what makes your blood red.

What do red blood cells do?

Red blood cells play an important role in your body by carrying oxygen from your lungs to other parts of your body.

Red blood cells help remove waste products from your body, such as carbon dioxide. Red blood cells carry carbon dioxide to your lungs, where it's breathed out.

How are red blood cells made?

Red blood cells are made in your bone marrow, which is the inside of your bones. This is where all your blood cells are made.

How do I keep my red blood cells healthy?

A healthy diet containing essential vitamins and minerals will help your body produce enough red blood cells and help them function normally.

To make red blood cells, your body needs nutrients such as vitamin B12, folate and iron.

Vitamin B12 is only found in meat, eggs and dairy. It is often added to bread and cereals. Some people may need to take supplements, such as:

  • those on a vegetarian or vegan diet
  • people who are pregnant or breastfeeding

People who drink too much alcohol are also often low in B vitamins.

You can read more about foods that are high in vitamin B.

Iron is important to help your red blood cells carry oxygen around your body. Iron is an essential mineral that you get from some foods that are high in iron, such as:

  • red meat
  • eggs
  • green leavy vegetables
  • whole grains

If you are a vegetarian or a vegan, you need to be careful you have enough iron in your diet, and you may need supplementation.

What are problems involving red blood cells?

Not having the right amount of red blood cells may indicate an underlying problem.

Not enough red blood cells

It's quite common for people to develop anaemia. This happens when you do not have enough red blood cells. Anaemia can be caused by:

  • lack of iron or vitamins in your diet
  • side effects of medicine
  • certain inherited diseases
  • bone marrow disease
  • cancer and treatments, such as chemotherapy
  • some chronic diseases – such as kidney failure

It can also be caused by blood loss, such as from:

  • bleeding from your colon
  • heavy periods
  • childbirth

If you have severe anaemia, you may need a blood transfusion. In some cases, you can avoid a blood transfusion through 'patient blood management', a process that boosts and conserves your own blood. Discuss this with your doctor.

Too many red blood cells

There can be problems with having too many red blood cells, too, although this is not as common. This is called polycythaemia or erythrocytosis.

There are several different causes of polycythaemia.

The shape of your red blood cells

Some diseases affect the formation of red blood cells. These can result in abnormally shaped red blood cells which don't function properly.

People with thalassaemia do not produce enough healthy haemoglobin. This makes your blood cells small and pale. People with thalassaemia aren't always able to move oxygen around the body properly. There are several different types of thalassaemia. Some are so mild that you may not know that you have it. Other types can be so bad that they can cause very severe illness or death shortly after birth.

Sickle cell disease is an inherited condition which causes your red blood cells to form a crescent shape. People with sickle cell anaemia are often tired and have pale skin.

If you have any concerns, talk to your doctor.

Resources and support

For more information on the blood and red blood cells, you can visit:

You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available to speak with 24 hours a day, 7 days a week.

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: October 2023

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