Ageing of the immune system (Immunosenescence)

As we age our immune system becomes less effective and we are more likely to fall ill. Can we do anything about this, so that we stay healthier for longer? 

What is our immune system? 

This is our body’s defence system. Cells, tissues and organs work together to protect us against bacteria, viruses, parasites and cancer. 

We are born with an innate immune system. This is our first line of defence, providing a barrier against infection. As we grow, a parallel (adaptive or acquired) immune system evolves. This works out how to respond to new threats and ‘remembers’ threats it has faced, so it can stop them next time. 

What happens to our immune system as we get older? 

Our immune system tends to become less efficient and less reliable as we get older. This decline is known as immunosenescence ie ageing of our immune system. It has a number of different causes, including shrinking of the thymus gland.

What are the health implications?

  • Vaccinations for the elderly become less effective
  • Autoimmune disorders can develop, like MS or rheumatoid arthritis. The immune system no longer distinguishes between healthy body tissue and harmful substances such as cancer cells, viruses and toxins - and begins to destroy the healthy tissue.
  • The ability to detect and correct cell defects reduces. This can result in an increase in the risk of cancer.
  • Areas such as the brain depend on the immune system for maintenance. If there are not enough immune cells to cope with degeneration in the brain, complications can begin to occur, including Alzheimer's.

Can we do anything to maintain our immune system? 

Yes. The good news is that a healthy lifestyle helps maintain our immune system. 

  • Regular exercise has been shown to have a positive effect on the immune system of older people. 
  • Vitamin D (available through the sun on our skin and, in smaller amounts, from oily fish, eggs and fortified breakfast cereals). A deficiency of vitamin D can affect the immune system and increase susceptibility to illness 
  • Meditation and breathing exercises may help strengthen the immune system.  
  • Maintaining and building positive relationships and social networks also seem to be good for our immune system. In contrast loneliness seems to have an adverse effect.  
  • Even sex may help. That’s according to Dr Carl Charnetski. His research showed that people who reported having sex once or twice a week enjoyed higher levels of Immunoglobulin A. This is an antibody that helps fight disease. 

Might some answers be found in space? 

Since April 2014, researchers at the International Space Station have been working with NASA and the National Institute of Ageing. They are hoping to find new ideas on how to keep the immune system functioning better for longer.  It seems that microgravity causes the same level of immune system dysfunction during spaceflight, as immune system deterioration during ageing.

What are other causes and effects of ageing? 

See Ageing - How and Why?


The body’s immune system tends to decline with age. However there are ways we can increase the chances of our immune system functioning longer, in particular 

  • Exercise regularly and eat nutritious food
  • Manage stress – through relaxation, meditation or breathing exercises
  • Get a good night’s sleep
  • 10–15 minutes of sun on your skin per day, to boost your Vitamin D
  • Maintain and build relationships with family and friends

Emma Juhasz 

Reviewed 16/07/14, next review date February 2017