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How your immune system changes as you get older

Siski Green / 21 January 2015

As you age your immune system doesn’t work so well, find out why with our guide to the ageing immune system.

Echinacea flowers
How does age affect your immune system and what can you do about it

Why your immune systems stops recognising intruders

Your body when young is efficient at recognising harmful viruses or bacteria in the body and, as a result, reacts appropriately. As you age, this ability decreases. This means that even when you don’t have a foreign or harmful substance in your body, your body may respond as though it does – resulting in autoimmune disorders, which can be extremely harmful.

How your body's ability to fight infection is reduced

It’s not just remembering where you put your car keys that becomes more difficult as you age, your T cells are also less effective at remembering antigens and responding quickly – and this means that your body’s ability to fight infection is impeded. 

How age affects your immune system's response

Where your body once attacked foreign bodies or substances in your bloodstream quickly and efficiently, it’s now slower to respond and slower to produce the macrophages – a type of white blood cell which destroys harmful foreign cells or bacteria – necessary for fighting an infection. Researchers theorise that this is why older people are at higher risk of cancer. 

Why fewer useful cells and antibodies weaken your immune system

The amount of white blood cells your body produces decreases as you age, putting you at risk of infection too. Similarly, if you are hit with an infection, the body produces less proteins in response, which are needed to fight it. The body produces fewer antibodies in response to an immune attack too. This, say researchers, is probably why older people don’t experience the same protection from vaccines as younger people. 

How reduced circulation affects your immune system

As you age your heart isn’t as strong as it used to be and you may find yourself with a less effective circulation. Swollen ankles, pins and needles, numb body parts – all of these can be a result of less effective circulatory system. But this also means that your body can’t get white blood cells around the body as quickly or effectively and that in turn means it’s less effective at fighting an infection. The virus or bacteria will have more time and space to grow and flourish.


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The opinions expressed are those of the author and are not held by Saga unless specifically stated. The material is for general information only and does not constitute investment, tax, legal, medical or other form of advice. You should not rely on this information to make (or refrain from making) any decisions. Always obtain independent, professional advice for your own particular situation.