our immune responses, through supplements or superfoods.

But is it even possible to alter how the body responds to disease

through an immune-boosting pill or by eating blueberries?

And what about the people who take it even further?

The biohackers experimenting with procedures such as

faecal transplants -

basically taking someone else's poo as a medicine

in an attempt to cure a range of ills.

Dangerous experimentation or smart science?

The immune system is part of an interconnected system,

running all the way through our body.

Involving all our tissues, from our skin,

all the way through to our toes.

And in fact, the gut has one

of the largest resident populations

of immune cells in our body.

Most of the body's immune cells are found in the lining of the intestine,

and the microbes in our gut play a crucial role

in keeping those immune cells of our body healthy.

And they do that by providing the key chemical signals

that they get once they digest

the good foods that we eat.

So a healthy gut microbiome

is absolutely critical to a healthy immune system.

The immune system is considered to be an organ.

But unlike ever other organ in your body,

it's one where components

of the system

can migrate around the body.

You don't expect that with cells from your lungs,

from your spleen, or any other solid organ.

But the beauty of the immune system

is it has a property of immuno-surveillance.

Immunological surveillance is when the cells of the immune system

come together to coordinate a response to an external threat

such as disease.

For example, your lymph nodes,

the glands that swell up when you are sick,

are a sign of your immune system at work.

We often hear messages encouraging us to boost our immune system.

So, could we just take a pill to do that?

When you do meet an infectious threat,

our immune response has to react quickly -

to contain the threat and eradicate it.

And you don't want it to stay on, because if it says on, it's damaging.

And that is what happens in allergy and autoimmune disease,

which are over-reactivity of the immune response.

So there is no wonder pill that is going to restore and boost one part

of the immune response to help us be super-powered,

because it's all so interconnected,

and the risks of getting it wrong are really quite dramatic.

So, instead of boosting our immune system,

we should focus on supporting it.

Everything that we know already which is good for our health

will also benefit our immune system.

More exercise, taken at regular intervals,

has been shown to boost your immune function.

That's been shown, and that's published data.

Unfortunately, the modern lifestyle

is not very good for our immune system.

Our diets of convenience foods

and fatty foods that are low in fibre

alongside sedentary lifestyles with little exercise,

high stress and not too much sleep - too much screen time.

All of these combine to make our immune response

not work as it should.

Getting enough sleep and reducing stress

can help our immune system operate at an optimal level.

And even though one blueberry won't work miracles,

getting a variety of the right foods, is very important.

To help your immunity you need to be feeding up your gut microbes,

and the best way to do this is to make them more diverse -

give them more species.

And I recommend 30 different types of plant a week,

which gives you all the fibre you should need.

Secondly, you should pick plants to eat that are high in polyphenols.

These are the chemicals that are naturally found in plants

that are actually rocket fuel for your gut microbes.

So things like brightly coloured berries,

strong flavours like coffee beans,

dark chocolate and even red wine contain polyphenols.

So, if what you eat and your gut is so important for your immune system,

why are some people transplanting other people's poo

into their own stomachs?

Faecal microbial transplant or, colloquially, a poo transplant,

is taking a sample of a stool from a normal person

and putting it into someone who is unwell.

This has been done for several decades

for very bad infections of the bowel, like Clostridium difficile,

and it cures 90% of people.

And it's been since started to be used in a number of other conditions.

This is a fascinating area of research,

but definitely not to be tried at home, says Tim.

I think this is an exciting new form of therapy,

but it's always best to do this within the confines

of a medical clinic,

where things can be supervised and the risk of side effects

or infection is extremely low.

There are some people who take risks and do do it at home,

and those risks will be multiplied considerably.

There's a lot of hype about faecal transplants,

and you mustn't believe people who say that it works with everything,

in everybody, it certainly doesn't,

and there are many failures in clinical trials.

One of the ways we can effectively and safely manipulate

our immune responses is through vaccination.

What a vaccine is doing is essentially giving you

the parts of the germ that will stimulate the immune response,

without actually getting the full blown infection.

Another thing that we can do,

is actually try to switch the immune response off.

For some diseases we don't want a powerful immune response,

because that's what's causing the damage.

This is exactly what's done in diseases like rheumatoid arthritis,

multiple sclerosis,

or is also being investigated in infections like Covid.

The good news is, whilst there's no one magic pill we can take

to boost our immune response, the more scientists learn about

how our immune system works, the more they can develop

new drug treatments and therapies to combat a wide range of diseases.

The knowledge of science is actually leading to all sorts of wonderful

new possibilities to help treat us and win the war against infection.