0:00:02 > 0:00:04CHILD COUGHS
0:00:06 > 0:00:08We are in the middle of an allergy epidemic.
0:00:08 > 0:00:09- MAN:- Look up, lift your chin.
0:00:10 > 0:00:13One in three of us suffer from allergies like eczema,
0:00:13 > 0:00:15asthma or hay fever...
0:00:15 > 0:00:18- CHILD COUGHS - Just going to do the last bit on your face.
0:00:18 > 0:00:22..and they send more than 20,000 of us to hospital every year.
0:00:27 > 0:00:29To find out why,
0:00:29 > 0:00:32Horizon has pushed the very latest science to the limits...
0:00:34 > 0:00:37..with an extraordinary experiment.
0:00:39 > 0:00:42Every aspect of the lives of two allergic families
0:00:42 > 0:00:44have been put under the microscope...
0:00:44 > 0:00:46- BOY:- Jasper!
0:00:48 > 0:00:49- MAN:- Aah! No!
0:00:49 > 0:00:54..in order to find out why so many of us are becoming allergic.
0:01:09 > 0:01:11- MAN:- And jump! Yeah, good boy.
0:01:13 > 0:01:16We've rigged our two families' homes, and everyone in them,
0:01:16 > 0:01:18with mini cameras.
0:01:20 > 0:01:22And we've tracked their movements with GPS.
0:01:22 > 0:01:24Morning!
0:01:24 > 0:01:25- CHILD:- Morning.
0:01:28 > 0:01:33We're going to follow Caroline, Freya, Joe and Danny.
0:01:34 > 0:01:36JOE: This is me doing my medicines.
0:01:38 > 0:01:43And Dana, Paul, Morgan and his baby brother, Jenson.
0:01:45 > 0:01:47You can have some Piriton.
0:01:48 > 0:01:52Between them, they have an impressive array of allergies.
0:01:56 > 0:01:58I've got nuts...
0:01:58 > 0:02:02I've got cats and dogs, and dust mites.
0:02:04 > 0:02:05Eggs...
0:02:06 > 0:02:07The...kiwi...
0:02:09 > 0:02:10Avocado...
0:02:11 > 0:02:12Banana.
0:02:14 > 0:02:18Can you eat dairy? What about nuts and soya?
0:02:18 > 0:02:19Is that everything?
0:02:19 > 0:02:21- More.- More?- Is there anything else?
0:02:21 > 0:02:23- Lots more.- Lots more.
0:02:23 > 0:02:25MORGAN SQUEAKS
0:02:25 > 0:02:30Latex, dust, cats, dogs, pollen and horses?
0:02:30 > 0:02:34- Yes...I think that's it. - So quite an extensive list!
0:02:34 > 0:02:37Boo! Boo! JENSON GURGLES
0:02:37 > 0:02:41Extensive it may be, but it's the impact it has on their daily lives
0:02:41 > 0:02:44that's both surprising and shocking.
0:02:49 > 0:02:54I wash and clean and Hoover twice a day, and sweep as much as I can.
0:02:55 > 0:02:58Well, literally, all of his clothing are 100% cotton
0:02:58 > 0:03:02and he's got this all-in-one eczema top that covers his hands.
0:03:02 > 0:03:05We had this bed built so it was much higher up,
0:03:05 > 0:03:08so he wasn't at dust level.
0:03:08 > 0:03:10He's also got all-in-one sort of leggings.
0:03:10 > 0:03:15They even do a balaclava, but he wouldn't wear that now at his age.
0:03:15 > 0:03:17As soon as he's up, out of bed in the mornings,
0:03:17 > 0:03:20I have to take all the bedding off, give it a Hoover.
0:03:20 > 0:03:24And he has to soak in the bath for about ten to 15 minutes.
0:03:24 > 0:03:26And all his soft toys we have to wash as well,
0:03:26 > 0:03:28just to make sure that there's no dust on them.
0:03:28 > 0:03:30And then go in the living room and do his creams.
0:03:35 > 0:03:38It is hard to fit it all in, but I think it does become
0:03:38 > 0:03:41a way of life that, you know, we just get used to doing it.
0:03:44 > 0:03:47Because we're following our families 24 hours a day,
0:03:47 > 0:03:50we'll know where they go and what they do...
0:03:51 > 0:03:55..allowing us to try and shed light on why they may be allergic.
0:03:56 > 0:03:58- SHOUTS:- Coming, ready or not!
0:03:58 > 0:04:00JOE EXHALES DEEPLY
0:04:02 > 0:04:06- DANNY:- 'Yeah, I've never heard of this like this, years and years ago,
0:04:06 > 0:04:08'so why is it all happening now?'
0:04:08 > 0:04:11- DANA:- Ready...jump! Oh!
0:04:11 > 0:04:14And it makes you wonder is there something that we're doing or
0:04:14 > 0:04:20is it something that we're putting on our kids without us even knowing?
0:04:24 > 0:04:26CAROLINE: 'I kind of think to myself,
0:04:26 > 0:04:29' "Was it the births that could have caused his problems?"
0:04:29 > 0:04:31'because his birth was quite traumatic.'
0:04:32 > 0:04:34I'm convinced it might have something to do with it
0:04:34 > 0:04:37cos that's the only thing I can think that I've done differently.
0:04:37 > 0:04:40- CHILD PANTS - Might be a good time to... - Do you need your pump?
0:04:40 > 0:04:44- Do you need your pump? - I'll get his pump.
0:04:44 > 0:04:46As our families search for answers,
0:04:46 > 0:04:50so too are scientists around the world.
0:04:50 > 0:04:52SEAGULLS SQUAWK
0:05:02 > 0:05:06Scientists like Professor Syed Hasan Arshad
0:05:06 > 0:05:08from the University of Southampton.
0:05:12 > 0:05:15He has studied the allergic health of people across Britain
0:05:15 > 0:05:18for the past 20 years.
0:05:27 > 0:05:31So allergic diseases have gone up significantly
0:05:31 > 0:05:33in the last three decades.
0:05:33 > 0:05:38Asthma, for example, was 1% or less in the 1950s.
0:05:39 > 0:05:44In the 1980s, most studies show that asthma prevalence has gone up to 10%
0:05:44 > 0:05:50or, even 12% to 13% in children and about 7% to 8% in adults.
0:05:50 > 0:05:55There has been a tenfold increase over a 30-year period.
0:05:56 > 0:06:01Today, between 25% and 30% of people in the UK
0:06:01 > 0:06:03suffer from one or more allergies,
0:06:03 > 0:06:07from hay fever to asthma, eczema to food allergies.
0:06:09 > 0:06:13'Allergies which used to be rare are now part and parcel
0:06:13 > 0:06:15'of our daily life.'
0:06:15 > 0:06:21Now, that increase cannot be assigned to genetics
0:06:21 > 0:06:25because our genetics doesn't change over three decades.
0:06:25 > 0:06:28It takes thousands of years to change,
0:06:28 > 0:06:32so something must have changed in our environment
0:06:32 > 0:06:35that influenced our genetics in such a way
0:06:35 > 0:06:38that the allergic diseases developed.
0:06:45 > 0:06:46But that environmental change
0:06:46 > 0:06:50is specific only to Westernised countries like the UK.
0:06:52 > 0:06:55The studies have shown very intriguing findings.
0:06:55 > 0:06:59If a family moves from a developing world to a developed country,
0:06:59 > 0:07:03the risk of allergy generally goes up.
0:07:10 > 0:07:13This pattern is seen across the Western world,
0:07:13 > 0:07:16from America to Italy, Australia to the UK.
0:07:18 > 0:07:22One study found that immigrants' risk of developing allergies
0:07:22 > 0:07:25rocketed more than threefold after living in a developed country
0:07:25 > 0:07:27for ten years.
0:07:32 > 0:07:36So there is something with the urbanisation,
0:07:36 > 0:07:39something with the Western lifestyle
0:07:39 > 0:07:42that tends to influence the risk of allergy.
0:07:44 > 0:07:49In the last few years, a new theory has emerged that could help explain
0:07:49 > 0:07:52why not just our families, but one in three of all of us
0:07:52 > 0:07:53are becoming allergic.
0:07:54 > 0:07:55Where was it?
0:07:55 > 0:07:57There's got to be some deer poo here somewhere.
0:07:59 > 0:08:01I can't find any now.
0:08:03 > 0:08:04There's some poo of some sort there.
0:08:09 > 0:08:11This is immunologist, Professor Graham Rook.
0:08:15 > 0:08:18And he believes that the most prolific organisms on the planet
0:08:18 > 0:08:21are behind the allergy epidemic.
0:08:21 > 0:08:22Deer poo!
0:08:23 > 0:08:28Micro-organisms, like bacteria and fungi.
0:08:29 > 0:08:34It is calculated that the animal kingdom deposits on this planet
0:08:34 > 0:08:38something like 14 billion tonnes of faeces per year.
0:08:38 > 0:08:41Now, faeces contain an enormous number of bacteria
0:08:41 > 0:08:43and also an enormous number of bacterial spores.
0:08:45 > 0:08:48But these bacteria aren't just found in faeces.
0:08:48 > 0:08:52Well, of course, the micro-organisms in bacteria in particular
0:08:52 > 0:08:53are absolutely everywhere.
0:08:53 > 0:08:55Even the air is full of bacteria.
0:09:05 > 0:09:07I mean, there are at least, on a day like this, in this park,
0:09:07 > 0:09:09I don't know...
0:09:09 > 0:09:12100,000, or maybe even a million per cubic metre of air.
0:09:13 > 0:09:15And if you're in the vicinity of animals,
0:09:15 > 0:09:17if one were in amongst the herd of deer over there,
0:09:17 > 0:09:19there would probably be... ten million.
0:09:26 > 0:09:30The problem is, modern living is separating us from microbiota,
0:09:30 > 0:09:32like these.
0:09:34 > 0:09:37Nowadays we live in a world where those organisms
0:09:37 > 0:09:40from the natural environment are almost completely absent.
0:09:40 > 0:09:43You eat your squeaky-clean apple from the supermarket
0:09:43 > 0:09:47and you live in a steel and glass enclosure with air-conditioning,
0:09:47 > 0:09:51and you're just not encountering the right microbiota.
0:09:55 > 0:09:59It's this reduced exposure to microbes that Rook believes
0:09:59 > 0:10:02is impacting our immune systems and making us more allergic.
0:10:03 > 0:10:07Now Horizon is seeing if the theory plays out in the real world.
0:10:09 > 0:10:13CAROLINE: Right now, take it out. Do it slowly.
0:10:13 > 0:10:16Then concentrate on putting it back in.
0:10:17 > 0:10:21As part of our experiment, we're not only tracking our families...
0:10:21 > 0:10:23CAROLINE: Very quick at that.
0:10:23 > 0:10:26..we've also asked them to swab the bacteria on their bodies
0:10:26 > 0:10:27and throughout their homes.
0:10:37 > 0:10:39Over the coming weeks,
0:10:39 > 0:10:44microbiologist Dr Lindsay Hall is going to examine the results.
0:10:44 > 0:10:47What happens is that we basically take these samples,
0:10:47 > 0:10:51we mash them all up and then we extract the microbial DNA.
0:10:51 > 0:10:54We then put this DNA into a sequencing machine
0:10:54 > 0:10:57that's able to tell us what the DNA sequence is.
0:10:57 > 0:11:00We can then do some very fancy analysis on this
0:11:00 > 0:11:03that then will be able to tell us exactly what bacterial species
0:11:03 > 0:11:06are present in each of our family members.
0:11:06 > 0:11:11So I'll know then, we'll know their bacterial communities before I actually meet them face-to-face,
0:11:11 > 0:11:13so I'm really looking forward to that.
0:11:14 > 0:11:16Lindsay is hoping that these bacterial communities
0:11:16 > 0:11:21will give our families some answers as to why they may be allergic.
0:11:27 > 0:11:28To understand this,
0:11:28 > 0:11:32we need to understand what happens during an allergic reaction.
0:11:34 > 0:11:36Whatever it is that triggers the response,
0:11:36 > 0:11:39whether it's eggs, nuts or dust mites,
0:11:39 > 0:11:42the reaction in the body is very similar.
0:11:43 > 0:11:47So, first of all, I'm just going to write some marks on here.
0:11:47 > 0:11:54One, two, three, ten, 11, 12...
0:11:57 > 0:12:01This is consultant paediatric allergist, Dr Adam Fox.
0:12:03 > 0:12:07This first one, we're actually going to use fresh milk
0:12:07 > 0:12:10and also some fresh raw egg.
0:12:12 > 0:12:14Today, he is using a skin prick test
0:12:14 > 0:12:17to initiate a very small allergic reaction in his patient
0:12:17 > 0:12:19to find out exactly what she's allergic to.
0:12:21 > 0:12:25Next, we've got some tahini, which is a pure form of sesame,
0:12:25 > 0:12:26all crushed up.
0:12:26 > 0:12:28So, I'm just going to put a little bit of that there.
0:12:28 > 0:12:32'An allergy is an inappropriate response by our immune system -
0:12:32 > 0:12:34'which is really designed to protect us
0:12:34 > 0:12:36'from things such as germs and viruses,'
0:12:36 > 0:12:38to something that's supposed to be harmless.
0:12:38 > 0:12:41For example, pollen or foods like peanut or milk,
0:12:41 > 0:12:44and this can cause a whole variety of different symptoms,
0:12:44 > 0:12:46some of which can be potentially life-threatening.
0:12:50 > 0:12:52Let me know if it hurts - I'll be as gentle as I can.
0:12:52 > 0:12:55If you are allergic to say, eggs,
0:12:55 > 0:12:57when you come into contact with them,
0:12:57 > 0:12:59your immune system goes into overdrive.
0:12:59 > 0:13:00You OK there?
0:13:00 > 0:13:02- Yeah.- Good.
0:13:02 > 0:13:04If there is an allergy, what will normally happen is
0:13:04 > 0:13:07what's called a wheal and flare reaction,
0:13:07 > 0:13:10which is a little itchy bump with some redness round it.
0:13:10 > 0:13:15This localised reaction happens just under the skin's surface,
0:13:15 > 0:13:18where in this case, the egg allergen binds to
0:13:18 > 0:13:22its specific allergic antibody, called IgE...
0:13:23 > 0:13:26..and this triggers the release of histamine.
0:13:32 > 0:13:35The effect that histamine has depends on which parts of the body it's acting on.
0:13:35 > 0:13:38So, for example, histamine in the skin will cause itchy spots.
0:13:38 > 0:13:41If it's released more deeply in the skin then it may cause swelling,
0:13:41 > 0:13:44something we call angioedema, and that could be quite dangerous
0:13:44 > 0:13:47if, for example, it's around the tongue or the throat.
0:13:48 > 0:13:50But if you're unlucky and you have a more severe reaction
0:13:50 > 0:13:52that we refer to as anaphylaxis,
0:13:52 > 0:13:55then it could involve difficulty in breathing,
0:13:55 > 0:13:57so particularly wheeziness,
0:13:57 > 0:13:59or sometimes again in severe reactions,
0:13:59 > 0:14:03a drop in blood pressure and that can be very serious indeed.
0:14:12 > 0:14:17In the UK, asthma attacks prove fatal for three people every day...
0:14:17 > 0:14:18Mummy, Dad thinks...
0:14:18 > 0:14:21..evidence that sometimes no matter how hard you try,
0:14:21 > 0:14:23allergies can't always be avoided.
0:14:25 > 0:14:27And as our families know first-hand,
0:14:27 > 0:14:30allergic reactions can be terrifying.
0:14:34 > 0:14:37It was just a normal day, I'd booked an appointment at the doctors.
0:14:37 > 0:14:40My father-in-law came with me, didn't even have his shoes on.
0:14:40 > 0:14:42He was just driving us in the car.
0:14:43 > 0:14:46And at the time we were told he wasn't allergic to dairy
0:14:46 > 0:14:48and he'd had a Mini Milk.
0:14:48 > 0:14:51And literally within half an hour of waiting for the doctors, he just deteriorated.
0:14:51 > 0:14:53He couldn't breathe properly.
0:14:53 > 0:14:55And then within, I suppose it was seconds, I looked at him
0:14:55 > 0:14:58and I could see that his lip was starting to swell.
0:14:58 > 0:15:00I've never seen somebody so small with you know -
0:15:00 > 0:15:02sorry for being on the camera -
0:15:02 > 0:15:05I've never seen somebody so small be so sick.
0:15:05 > 0:15:07Within seconds of being in the ambulance,
0:15:07 > 0:15:09Joe was on the nebuliser and they kind of controlled it for me,
0:15:09 > 0:15:13but it was so scary because I wasn't aware of what was going on.
0:15:13 > 0:15:15Anything to do with the mouth, the airways,
0:15:15 > 0:15:17could affect his breathing.
0:15:17 > 0:15:19It was one of those scary moments when I thought,
0:15:19 > 0:15:22"OK, this is really serious, and we have to deal with this,
0:15:22 > 0:15:24"like, this could be life-threatening."
0:15:25 > 0:15:27MORGAN COUGHS
0:15:27 > 0:15:29Oh, dear, you're coughing a fair amount.
0:15:29 > 0:15:33- Oh, darling... Oh, darling!- Ugh..
0:15:33 > 0:15:37- HE CONTINUES COUGHING - Ohhhhh, it's exhausting, isn't it?
0:15:37 > 0:15:40In recent years, many theories have tried to explain
0:15:40 > 0:15:42why more children like Morgan
0:15:42 > 0:15:45are suffering from allergies than ever before.
0:15:46 > 0:15:49But Graham Rook believes that the evidence for them
0:15:49 > 0:15:51just doesn't stack up.
0:15:51 > 0:15:53It doesn't look as though it's the genes.
0:15:53 > 0:15:55It doesn't look as though it's pollution.
0:15:55 > 0:15:58It doesn't look as though you can explain it just by vitamin D
0:15:58 > 0:15:59and lack of sunlight.
0:15:59 > 0:16:02It doesn't look as though it's exposure to allergens
0:16:02 > 0:16:04because people were always exposed to allergens.
0:16:04 > 0:16:05So, what is it?
0:16:05 > 0:16:09Something in the environment has changed that is causing allergies
0:16:09 > 0:16:11to become more common.
0:16:22 > 0:16:26Rook believes it's changes to the bacteria in the environment.
0:16:28 > 0:16:29But this idea isn't entirely new.
0:16:34 > 0:16:3725 years ago, the "hygiene hypothesis"
0:16:37 > 0:16:41suggested that improved levels of hygiene and cleanliness
0:16:41 > 0:16:44reduced children's exposure to bacteria and viruses,
0:16:44 > 0:16:45and so, infections.
0:16:47 > 0:16:50This supposedly deprived their immune systems
0:16:50 > 0:16:53from the training they needed to resist allergies...
0:16:54 > 0:16:58..and the idea that we were all too clean was born.
0:17:01 > 0:17:05In fact, that just doesn't hold water.
0:17:06 > 0:17:10Largely, one of the most important reasons for rejecting that notion
0:17:10 > 0:17:12is the fact that those kinds of infection
0:17:12 > 0:17:16are commonest in the inner cities, commonest amongst the very people
0:17:16 > 0:17:19in whom the increases in allergic disorders are the most frequent.
0:17:19 > 0:17:21It simply didn't fit epidemiologically.
0:17:23 > 0:17:26Rook believes a much broader range of micro-organisms
0:17:26 > 0:17:29than childhood infections are to blame.
0:17:29 > 0:17:31Micro-organisms that our ancient ancestors
0:17:31 > 0:17:33were continually exposed to.
0:17:35 > 0:17:37Humans are really a grassland species.
0:17:37 > 0:17:40Two and a half million years ago we were hunting and gathering
0:17:40 > 0:17:43and scavenging in this sort of environment,
0:17:43 > 0:17:45and in constant contact with the soil
0:17:45 > 0:17:46and with the organisms
0:17:46 > 0:17:48from the animals they were killing,
0:17:48 > 0:17:51and so enormous exposure to types of micro-organism
0:17:51 > 0:17:53that we simply don't encounter any more,
0:17:53 > 0:17:56because we live in these concrete blocks made of glass
0:17:56 > 0:18:01and steel and strange materials treated with biocides and glues.
0:18:09 > 0:18:12It's changes to all of these old microbes, be they bacteria,
0:18:12 > 0:18:16fungi or viruses, that is at the crux of this new theory.
0:18:21 > 0:18:22We've been suggesting
0:18:22 > 0:18:25that a term that could replace the hygiene hypothesis
0:18:25 > 0:18:27is the "Old Friends mechanism",
0:18:27 > 0:18:31because the problem is not a lack of exposure
0:18:31 > 0:18:33to the childhood infections,
0:18:33 > 0:18:37it's actually a lack of exposure to those old organisms
0:18:37 > 0:18:41that we had to tolerate throughout our evolution.
0:18:41 > 0:18:45They're the ones that provide the data that the immune system needs
0:18:45 > 0:18:47to correctly set up its regulatory pathways,
0:18:47 > 0:18:50correctly set up the police force that stops the immune system
0:18:50 > 0:18:52from doing anything stupid.
0:18:57 > 0:18:58A bit more?
0:18:58 > 0:19:00Yeah. Oh, yeah, a bit more than that. Tip it in.
0:19:00 > 0:19:02The Old Friends mechanism
0:19:02 > 0:19:05may explain not only the increase in allergies,
0:19:05 > 0:19:08but other chronic inflammatory disorders as well.
0:19:08 > 0:19:11- Did it just in time. - You did, didn't you?
0:19:11 > 0:19:13And as our families continue to have
0:19:13 > 0:19:15every aspect of their lives monitored,
0:19:15 > 0:19:19we want to see if there's evidence for it in the real world too.
0:19:24 > 0:19:28It's only in recent years that scientists have come to understand
0:19:28 > 0:19:32the extent to which bacteria are a vital component of the human body.
0:19:35 > 0:19:38One of the leaders in the field is gastroenterologist,
0:19:38 > 0:19:40Professor Fergus Shanahan.
0:19:46 > 0:19:49We call them microbes because they're tiny,
0:19:49 > 0:19:52we can't see them, but they're there all right.
0:19:52 > 0:19:55Most of the bacteria are on the skin, in the mouths,
0:19:55 > 0:19:58in body cavities, but the vast majority are present
0:19:58 > 0:20:01in the large intestine, otherwise known as the colon.
0:20:03 > 0:20:06The degree to which we're covered in our bacterial associates
0:20:06 > 0:20:07is staggering.
0:20:10 > 0:20:15People use loose numbers to describe the vast numbers of organisms,
0:20:15 > 0:20:19but it's something in the range of tenfold the number of human cells.
0:20:19 > 0:20:23This is equivalent to hundreds and hundreds of billions of bacteria
0:20:23 > 0:20:24in and on the human body.
0:20:29 > 0:20:30Bacteria are so numerous,
0:20:30 > 0:20:33they make up the bulk of living matter on Earth.
0:20:34 > 0:20:37But they're not merely bystanders.
0:20:40 > 0:20:43We think of bacteria generally as being something harmful,
0:20:43 > 0:20:46something that could cause disease, something that could spoil food,
0:20:46 > 0:20:47but the truth is
0:20:47 > 0:20:50bacteria are actually predominantly beneficial to us.
0:20:51 > 0:20:55They produce vital nutrients, they help us digest food
0:20:55 > 0:21:00and they provide protection for us against infectious organisms.
0:21:00 > 0:21:02They're an active participant in human life.
0:21:05 > 0:21:09It doesn't work very well, but it's the best they've got at the moment
0:21:09 > 0:21:12- cos we just don't...- I know, that's the problem...- Yeah...
0:21:12 > 0:21:14Bacteria are now known to do so much in the human body
0:21:14 > 0:21:18that they're often referred to as the "forgotten organ".
0:21:19 > 0:21:22And for our families, their bacteria are no different.
0:21:24 > 0:21:27Dr Lindsay Hall has brought them together
0:21:27 > 0:21:30because the results from their bacterial swabs are back.
0:21:30 > 0:21:33Though, unfortunately, Morgan wasn't well enough to join.
0:21:33 > 0:21:35The last couple of years we've designed...
0:21:35 > 0:21:37Interestingly, the first and most obvious thing
0:21:37 > 0:21:39that Lindsay's discovered
0:21:39 > 0:21:43is with regards to the diversity of their samples.
0:21:43 > 0:21:46So what does diversity mean in terms of bacteria?
0:21:46 > 0:21:48Well, if you look at this picture here,
0:21:48 > 0:21:50this is a picture of our intestine
0:21:50 > 0:21:54and these are all the different types of bacteria that call it home.
0:21:54 > 0:21:58So, it's an unbelievably complex ecosystem.
0:21:58 > 0:22:01So, if we think about ecosystems, we think about the oceans,
0:22:01 > 0:22:03maybe, you know, the rainforests, things like that,
0:22:03 > 0:22:06but actually, the most densely kind of colonised ecosystem
0:22:06 > 0:22:10and the most diverse in the world is our gut.
0:22:13 > 0:22:17The problem is, like the rest of us in the Western world,
0:22:17 > 0:22:20both our families had a relatively low diversity of bacteria
0:22:20 > 0:22:22in their guts...
0:22:23 > 0:22:26..especially when compared to a tribe of people
0:22:26 > 0:22:29who live as close to the lifestyles of our ancient ancestors
0:22:29 > 0:22:31as it's possible to get.
0:22:34 > 0:22:36These are the Hadza.
0:22:37 > 0:22:40In the Rift Valley of northern Tanzania,
0:22:40 > 0:22:43they hunt game, gather honey
0:22:43 > 0:22:46and forage for berries, fruits and plants to survive.
0:22:47 > 0:22:49Yeah, so I don't know if, Paul and Danny,
0:22:49 > 0:22:51this is how you go out to go and get your lunch?
0:22:51 > 0:22:53- SHE LAUGHS - It's close.
0:22:53 > 0:22:56It's just got... It's just got a Pret round the corner.
0:22:56 > 0:22:58DR HALL LAUGHS
0:22:58 > 0:23:00But it looks like tribes like the Hadza
0:23:00 > 0:23:03have this high diversity of their good bacteria
0:23:03 > 0:23:06and they don't have many allergies.
0:23:08 > 0:23:09In one hunter-gatherer tribe,
0:23:09 > 0:23:13just one in every 1,500 people had an allergy,
0:23:13 > 0:23:17compared to one in three in the UK.
0:23:19 > 0:23:22And it seems the diversity of microbes in the gut
0:23:22 > 0:23:25is key when it comes to allergies.
0:23:30 > 0:23:33It was interesting for me looking at your samples,
0:23:33 > 0:23:41that Joe and Morgan had lower total bacterial diversity than...you guys.
0:23:42 > 0:23:45And there's lots of studies out there that show that
0:23:45 > 0:23:48individuals that have got allergies, they have a lower diversity
0:23:48 > 0:23:51in comparison to healthy... healthy people.
0:23:51 > 0:23:52So individuals that have got...
0:23:52 > 0:23:55Not only do people in the West have lower bacterial diversity,
0:23:55 > 0:23:58but those with allergies have even less.
0:23:58 > 0:23:59..Allergies, and so...
0:23:59 > 0:24:04And incredibly, brand-new research is proving how this lack of bacteria
0:24:04 > 0:24:06may be making us more allergic.
0:24:20 > 0:24:23This is Associate Professor Ben Marsland.
0:24:26 > 0:24:29He's undertaken a unique experiment here in the Swiss Alps.
0:24:30 > 0:24:32OK.
0:24:35 > 0:24:38This is the Ecole Polytechnique Federale de Lausanne.
0:24:48 > 0:24:51And the creatures that call this place home,
0:24:51 > 0:24:55show what happens when you grow up without any bacteria at all.
0:24:59 > 0:25:02MICE SQUEAK
0:25:02 > 0:25:04These are germ-free mice.
0:25:07 > 0:25:11Well, a germ-free mouse has no bacteria, no viruses,
0:25:11 > 0:25:15no fungi at all, so it's absolutely pure and clean.
0:25:15 > 0:25:16For all intents and purposes,
0:25:16 > 0:25:19a germ-free mouse like this looks like a normal mouse.
0:25:19 > 0:25:22It breathes normally, it grows normally, it looks normal.
0:25:22 > 0:25:27The only difference is there are no microbes there at all.
0:25:32 > 0:25:37The mice may look quite normal, but keeping them free of any bacteria
0:25:37 > 0:25:42has astonishing consequences when they're exposed to common allergens.
0:25:44 > 0:25:47So we took house dust mite allergens,
0:25:47 > 0:25:50which is one of the most common types of allergens found in the household,
0:25:50 > 0:25:53and we put them down the nose of the mice
0:25:53 > 0:25:55to see what type of response they would have.
0:25:55 > 0:25:59And we compared that between a germ-free mouse and a normal mouse.
0:26:03 > 0:26:06The difference between the two types of mice is profound.
0:26:11 > 0:26:15Some of the ways that we can measure an allergic response is by looking
0:26:15 > 0:26:17at the lung tissue itself,
0:26:17 > 0:26:20and in this picture we've got airways in a normal mouse
0:26:20 > 0:26:25where the main air is being inhaled and alveoli around it.
0:26:25 > 0:26:27So this is quite a healthy lung.
0:26:28 > 0:26:29Now, if we look at a germ-free mouse,
0:26:29 > 0:26:32you can see that the picture has changed dramatically.
0:26:32 > 0:26:34The purple staining, which is the mucus production,
0:26:34 > 0:26:37and so we know that in that setting in the absence of these microbes,
0:26:37 > 0:26:40there's much more mucus production in the airway,
0:26:40 > 0:26:42so it's much more difficult to breathe.
0:26:42 > 0:26:45Also around these airways, we're finding inflammatory cells
0:26:45 > 0:26:48and these are some of the most dangerous cells
0:26:48 > 0:26:51involved in an allergic asthma response.
0:26:51 > 0:26:53So with that very first simple experiment,
0:26:53 > 0:26:57what we've found was that in the absence of any microbes at all,
0:26:57 > 0:26:59the mice were more prone to allergy.
0:27:08 > 0:27:11Normally, exposure to harmless bacteria
0:27:11 > 0:27:13helps to dampen down the immune system.
0:27:19 > 0:27:22So, as we get exposed to microbes,
0:27:22 > 0:27:25this teaches the immune system to develop appropriately,
0:27:25 > 0:27:28so that it knows how to respond against pathogens
0:27:28 > 0:27:30when they are encountered.
0:27:34 > 0:27:38And importantly, not respond to harmless things in the environment
0:27:38 > 0:27:40like pollen or peanuts.
0:27:41 > 0:27:44And if you don't have that education,
0:27:44 > 0:27:46or the education is not complete,
0:27:46 > 0:27:51perhaps that's why there's more of a chance to develop allergies.
0:27:56 > 0:27:59Without everyday exposure to bacteria,
0:27:59 > 0:28:01our immune systems can overreact.
0:28:05 > 0:28:09And it seems that perhaps the most important window of opportunity
0:28:09 > 0:28:12for this education, is right at the beginning of life.
0:28:16 > 0:28:20It's well-documented that people who grow up on traditional farms
0:28:20 > 0:28:22are often protected from allergies...
0:28:22 > 0:28:24SHEEP BLEAT
0:28:24 > 0:28:26..perhaps because of the huge variety of bacteria
0:28:26 > 0:28:28surrounding them.
0:28:29 > 0:28:32But for farmers, and in fact all of us,
0:28:32 > 0:28:33it's the first year of life
0:28:33 > 0:28:37that is the most critical for microbial health.
0:28:39 > 0:28:41So, she's getting down now.
0:28:41 > 0:28:43It starts at the moment of birth itself.
0:28:45 > 0:28:47These sheep have carried their lambs for five months,
0:28:47 > 0:28:52but like humans, life in the womb is very different to the outside world.
0:28:52 > 0:28:54You can see she's sort of straining a bit.
0:28:55 > 0:28:57Whilst in the womb, babies are thought to be
0:28:57 > 0:29:02almost completely sterile, but that all changes during birth.
0:29:03 > 0:29:05SHEEP BLEATS
0:29:06 > 0:29:08It's all right, darling.
0:29:09 > 0:29:10You ready?
0:29:12 > 0:29:18In humans, the microbiota of the vagina changes before birth.
0:29:18 > 0:29:21It's coming the right way.
0:29:24 > 0:29:28A group of bacteria called lactobacillus starts to dominate,
0:29:28 > 0:29:31bacteria that have been shown to protect against allergies.
0:29:34 > 0:29:37So, as with a new-born lamb, when the baby travels down through
0:29:37 > 0:29:42the birth canal, it gets covered in these bacteria from head to toe.
0:29:46 > 0:29:49In effect, our first allergy-protecting microbiome
0:29:49 > 0:29:51is born when we are.
0:29:58 > 0:30:01But 25% of babies in the UK
0:30:01 > 0:30:04are now born by Caesarean section every year.
0:30:06 > 0:30:09They're more typically colonised by bacteria found on the skin
0:30:09 > 0:30:12and hospital surfaces than the vagina.
0:30:12 > 0:30:17This may explain why a study of 1.7 million Norwegian children
0:30:17 > 0:30:21found that those born by Caesarean were 52% more likely to become
0:30:21 > 0:30:24asthmatic than those delivered vaginally.
0:30:26 > 0:30:30And it's now understood that breast milk contains up to 700 species
0:30:30 > 0:30:35of bacteria, possibly explaining why exclusively breast-fed babies
0:30:35 > 0:30:38are less likely to be allergic.
0:30:38 > 0:30:40Is that funny? Whee!
0:30:40 > 0:30:45But perhaps the greatest threat to children's microbes comes
0:30:45 > 0:30:48when the few bacteria they do have come under attack.
0:30:52 > 0:30:58As with any ecosystem, diversity is the key to a healthy gut flora.
0:31:00 > 0:31:03Yet one of the greatest advances in modern medicine
0:31:03 > 0:31:05is destroying that diversity...
0:31:07 > 0:31:11..often with devastating consequences.
0:31:25 > 0:31:27Well, antibiotics are designed
0:31:27 > 0:31:30to target infectious or harmful bacteria,
0:31:30 > 0:31:33which we've grown here on this laboratory Petri dish.
0:31:33 > 0:31:37We put this particular antibiotic into the centre,
0:31:37 > 0:31:40and you see a zone of clearance of the pathogen,
0:31:40 > 0:31:43the infectious agent, and that's good.
0:31:43 > 0:31:46That's a major advance that helps an awful lot of patients.
0:31:47 > 0:31:51The problem with this is the antibiotic is damaging
0:31:51 > 0:31:52the surrounding ecosystem.
0:31:52 > 0:31:56It's killing the beneficial harmless bacteria
0:31:56 > 0:31:58that we all have in our body.
0:32:01 > 0:32:05The diversity of our microbes is decimated following a course
0:32:05 > 0:32:09of antibiotics, not only leaving us vulnerable to attack
0:32:09 > 0:32:11by other infections,
0:32:11 > 0:32:15but threatening our long-term microbial health too.
0:32:19 > 0:32:22The microbiome is required to educate
0:32:22 > 0:32:24and help the immune system mature,
0:32:24 > 0:32:28so anything that threatens the microbiome tends to create a risk
0:32:28 > 0:32:32of some sort of abnormality of the immune system, and it has been shown
0:32:32 > 0:32:38several times now that the greater the number of antibiotic courses
0:32:38 > 0:32:41that one has, and particularly the earlier in life,
0:32:41 > 0:32:43particularly in infancy, the first year of life,
0:32:43 > 0:32:45the greater then the risk of allergies.
0:32:48 > 0:32:51One study found that giving babies under the age of one antibiotics
0:32:51 > 0:32:55increases their risk of developing eczema by 40%...
0:32:56 > 0:33:01..with every extra course increasing that risk by a further 7%.
0:33:02 > 0:33:05Are you watching me, Jenson?
0:33:05 > 0:33:09Of course, we mustn't abandon antibiotics all together,
0:33:09 > 0:33:12but if we are to preserve our microbial diversity,
0:33:12 > 0:33:13doctors must be mindful
0:33:13 > 0:33:17not to prescribe unnecessary courses of them.
0:33:21 > 0:33:25# Gently down the stream... #
0:33:25 > 0:33:28All this research suggests that modern living
0:33:28 > 0:33:31is denying children today the bacteria their immune systems require.
0:33:33 > 0:33:37This problem is particularly acute in those children with allergies.
0:33:37 > 0:33:41Lindsay has discovered the most allergic children in our families,
0:33:41 > 0:33:45Joe and Morgan, are missing some vital microbes.
0:33:45 > 0:33:49One of the bacteria that actually was similar for Joe and Morgan,
0:33:49 > 0:33:54in terms of it had far lower levels than what everybody else had within
0:33:54 > 0:33:59the families, was this bacterium here, which is acinetobacter,
0:33:59 > 0:34:03and there's some really interesting, very new studies that have suggested
0:34:03 > 0:34:07that individuals that have got asthma or eczema have low levels of
0:34:07 > 0:34:10this bacteria and that maybe relates to why they've got allergies.
0:34:10 > 0:34:13So these are one of the types of bacteria that's able
0:34:13 > 0:34:15to educate our immune system.
0:34:16 > 0:34:20But acinetobacter isn't the only type of bacteria that helps
0:34:20 > 0:34:21to educate our immune systems.
0:34:22 > 0:34:25The furry one that Freya is holding is bifidobacteria.
0:34:25 > 0:34:26You've probably heard of that
0:34:26 > 0:34:29because it's in a lot of probiotic kind of drinks and yoghurts.
0:34:29 > 0:34:32Look, it even looks friendly as well. That's excellent.
0:34:32 > 0:34:34Thanks, Freya. Hold it up for everyone to see.
0:34:34 > 0:34:36Brilliant.
0:34:36 > 0:34:37It's quite interesting
0:34:37 > 0:34:41because we looked at bifidobacteria levels in Morgan.
0:34:42 > 0:34:47He's not got any, and Joe did have some bifidobacteria,
0:34:47 > 0:34:51but at far lower levels in comparison to what you guys have got.
0:34:51 > 0:34:55One study found that five-year-olds with eczema had 28% fewer
0:34:55 > 0:34:59bifidobacteria as babies, compared to healthy children.
0:34:59 > 0:35:03It's possible that an early life experience may have reduced
0:35:03 > 0:35:07these allergy-protecting bacteria in Joe and Morgan.
0:35:08 > 0:35:10Can you think of any kind of early-life events
0:35:10 > 0:35:13that maybe happened to Morgan?
0:35:13 > 0:35:15Well, Morgan's been on antibiotics from a very young age.
0:35:15 > 0:35:18I know at about ten months, he had tonsillitis
0:35:18 > 0:35:20and they gave him antibiotics.
0:35:20 > 0:35:23Now, antibiotics are absolutely amazing
0:35:23 > 0:35:26and we need to take them to combat infections, we need that.
0:35:26 > 0:35:28But the problem is that they cause collateral damage,
0:35:28 > 0:35:31so they come in and get rid of the bad guys, but again,
0:35:31 > 0:35:34we're losing the good guys that are going to programme our immune system.
0:35:34 > 0:35:40And interestingly, Joe's birth may well have impacted his bacteria too.
0:35:40 > 0:35:43I kind of work it back to when he was born.
0:35:43 > 0:35:45His birth was really traumatic.
0:35:45 > 0:35:49He was starved of oxygen, he had the cord round his neck.
0:35:49 > 0:35:51He was sent off and it took quite a few days for him to become
0:35:51 > 0:35:54you know, become quite a normal child, as I see.
0:35:56 > 0:35:57Babies like Joe
0:35:57 > 0:36:00who spend their first hours of life in intensive care
0:36:00 > 0:36:02can miss out on their first flush
0:36:02 > 0:36:05of good bacteria from their mothers.
0:36:05 > 0:36:09And it can expose them to some less friendly microbes too.
0:36:11 > 0:36:14Like enterobacteriaceae.
0:36:14 > 0:36:17Interestingly, if you swab intensive care units in hospitals,
0:36:17 > 0:36:19this is what you find on the surfaces.
0:36:21 > 0:36:26And individuals that have allergies have higher levels of this bacteria,
0:36:26 > 0:36:28so that fits quite well with...
0:36:28 > 0:36:31Joe's got quite high levels of this, and if that's how Joe was born,
0:36:31 > 0:36:34then obviously this bacteria would maybe have colonised his gut.
0:36:40 > 0:36:43Our families' results are compelling.
0:36:43 > 0:36:46Clearly, there is something going on that's different to us,
0:36:46 > 0:36:49but we've never really understood how things are different
0:36:49 > 0:36:52internally for him, and understanding that, you know,
0:36:52 > 0:36:56there's certain bacteria that both myself, Caroline and Freya have,
0:36:56 > 0:36:59that Joe's lacking, it really brings it to light.
0:36:59 > 0:37:02Those 24 hours are vital in the first stages
0:37:02 > 0:37:04and you're not made aware of that.
0:37:04 > 0:37:07You don't think about that, you know, and the first time you start
0:37:07 > 0:37:09breast-feeding and then you stop breast-feeding
0:37:09 > 0:37:12and you put them onto formula, you don't think about any of this.
0:37:12 > 0:37:14You just think it's the natural thing to do.
0:37:17 > 0:37:20I think the biggest surprise was the bifidobacteria,
0:37:20 > 0:37:21where Morgan, you know...
0:37:21 > 0:37:24The average person has 40 million or so in their intestines
0:37:24 > 0:37:26and Morgan's got none.
0:37:27 > 0:37:32'That shows that it could be a huge part of why he suffers so badly
0:37:32 > 0:37:34'with the eczema and his allergies.'
0:37:36 > 0:37:38Luckily, there's just enough jam left, isn't there?
0:37:38 > 0:37:43With researchers from around the world studying the bacteria we rely on...
0:37:43 > 0:37:45Ta-dah! Your flapjacks!
0:37:45 > 0:37:47..we now have a better picture than ever before
0:37:47 > 0:37:51of how the modern world is impacting our old microbial friends.
0:38:07 > 0:38:10But interestingly, our lifestyles seem to be impacting
0:38:10 > 0:38:12some of our old microbial enemies too.
0:38:17 > 0:38:20Enemies that we've lived with for thousands of years.
0:38:26 > 0:38:29Humans in Palaeolithic times
0:38:29 > 0:38:32used to live in very small hunter-gatherer groups,
0:38:32 > 0:38:35sometimes probably only 20 to 30 people, and so only
0:38:35 > 0:38:39certain types of infection could persist within such groups.
0:38:40 > 0:38:43Graham Rook calls them the old infections
0:38:43 > 0:38:47and it's possible to get a glimpse of some of them here,
0:38:47 > 0:38:50at the Wellcome Collection in London.
0:38:53 > 0:38:57Home to a project called London's Pulse...
0:38:57 > 0:39:03a collection of 120 years of medical records from 1848 until 1972,
0:39:03 > 0:39:07recording births, deaths and diseases across the capital.
0:39:09 > 0:39:13This one in front of me is from the Metropolitan Borough of Finsbury,
0:39:13 > 0:39:17annual report for the year 1927.
0:39:18 > 0:39:20And it says here, "worms".
0:39:21 > 0:39:25Here's another one, 1918, East Ham.
0:39:25 > 0:39:26This one, "tapeworm".
0:39:26 > 0:39:27"Physis..."
0:39:27 > 0:39:29"Verminus heads".
0:39:29 > 0:39:31"TB in Stepney", and so it goes on.
0:39:31 > 0:39:35Down here we have "threadworms" and "roundworms."
0:39:35 > 0:39:38Now, roundworms, we just don't see those nowadays.
0:39:39 > 0:39:43OK, this is the year I was born, so this is exciting.
0:39:43 > 0:39:45"Tapeworm and TB".
0:39:45 > 0:39:48As far as I know, I was never exposed to tapeworm ova,
0:39:48 > 0:39:50but I could have been in 1946.
0:39:50 > 0:39:52That's fantastic.
0:39:55 > 0:39:59Old infections like parasitic worms and tuberculosis had to behave
0:39:59 > 0:40:03in a very specific way to survive in their hosts,
0:40:03 > 0:40:08be they early 20th-century Londoners or our more ancient ancestors.
0:40:08 > 0:40:11One, they had to not kill the individual,
0:40:11 > 0:40:15because obviously otherwise you just wipe out the hunter-gatherer group
0:40:15 > 0:40:17and that's the end of the career of that infection.
0:40:17 > 0:40:22And secondly, they had to be tolerated by the individual
0:40:22 > 0:40:25and the individual mustn't be able to eliminate them completely.
0:40:27 > 0:40:29The ability of these worms and infections
0:40:29 > 0:40:31to persist in their hosts was key.
0:40:34 > 0:40:38They evolved ways of quietening down the immune system,
0:40:38 > 0:40:40so that there wasn't massive inflammation
0:40:40 > 0:40:44causing permanent damage, and so our immune system sort of evolved to be
0:40:44 > 0:40:47rather dependent upon the presence of these organisms.
0:40:56 > 0:40:58So our immune system became less sensitive
0:40:58 > 0:41:01and ignored the old infections.
0:41:03 > 0:41:10But as a consequence, it ignored allergens in the environment too.
0:41:10 > 0:41:13In effect, old infections made us less allergic.
0:41:25 > 0:41:27This doesn't happen any more.
0:41:27 > 0:41:31Modern health care has wiped out the old infections.
0:41:33 > 0:41:37But living in groups of millions of people has allowed a new breed
0:41:37 > 0:41:40of crowd infections, like measles, to take their place.
0:41:45 > 0:41:47So the crowd infections,
0:41:47 > 0:41:50because they either killed you or you became immune to them,
0:41:50 > 0:41:54didn't evolve this ability to down-regulate the immune system.
0:41:54 > 0:41:58So it's a completely different host-parasite relationship,
0:41:58 > 0:42:01and of course what's happened nowadays is that modern medicine
0:42:01 > 0:42:04is starting to eliminate the old infections.
0:42:05 > 0:42:09We clearly don't want the persistent old infections like worms
0:42:09 > 0:42:10and TB in our lives.
0:42:13 > 0:42:16So what can we do to combat allergies?
0:42:17 > 0:42:21Can we reverse the damage done by the modern world to our old friends?
0:42:28 > 0:42:31Fergus Shanahan believes it is possible to improve
0:42:31 > 0:42:33the health of our bacteria.
0:42:33 > 0:42:36Two bananas, two onions.
0:42:38 > 0:42:40Yeah, that's good.
0:42:43 > 0:42:47And perhaps the easiest way to do this is to reconsider what we eat.
0:42:50 > 0:42:54Well, probiotics are generally commercially available
0:42:54 > 0:42:56bacteria in the form of a food.
0:42:56 > 0:42:59People have been consuming products similar to this
0:42:59 > 0:43:01for centuries, in the form of yoghurts and cheeses
0:43:01 > 0:43:04and other fermented food products, so it's not novel.
0:43:04 > 0:43:07These kinds of products can confer some health benefit,
0:43:07 > 0:43:10but it's important not to assume that they'll also treat
0:43:10 > 0:43:14a variety of non-specific claims that have been made for them.
0:43:14 > 0:43:16There is some science behind these, however.
0:43:16 > 0:43:18They're not completely snake oil,
0:43:18 > 0:43:21but one has to be judicious in the selection of these.
0:43:23 > 0:43:26The probiotics industry is now huge.
0:43:26 > 0:43:28Fergus is a scientific adviser for it,
0:43:28 > 0:43:30and his group at University College Cork
0:43:30 > 0:43:34have even patented their own strain of probiotic.
0:43:36 > 0:43:40But probiotics aren't the only tool out there to change gut bacteria.
0:43:41 > 0:43:45Another way of achieving the same thing is to take something
0:43:45 > 0:43:47in the food that can stimulate the natural growth
0:43:47 > 0:43:50of the naturally occurring bacteria, and that would be
0:43:50 > 0:43:54in the form of a diverse array of fruit and vegetables, for example.
0:43:54 > 0:43:57They contain essentially what scientists called prebiotics.
0:43:57 > 0:44:00These are generally of a carbohydrate nature,
0:44:00 > 0:44:02so when we consume these,
0:44:02 > 0:44:04we're actually promoting the growth of natural bacteria.
0:44:04 > 0:44:07We're also helping ourselves in terms of the absorption
0:44:07 > 0:44:08of essential nutrients.
0:44:08 > 0:44:13Changing our diet with pre- and probiotics only works
0:44:13 > 0:44:17as long as you keep it up, and even then, it's still not a wonder cure.
0:44:17 > 0:44:21Well, there is controversy about prebiotics and probiotics,
0:44:21 > 0:44:24and much of that controversy arises because of the assumption
0:44:24 > 0:44:28that a single bacterium can do everything for everyone.
0:44:28 > 0:44:29That's just not the case.
0:44:29 > 0:44:32It's the diversity that counts.
0:44:32 > 0:44:36No one food substance, no one bacterium,
0:44:36 > 0:44:38no one chemical in the food is sufficient
0:44:38 > 0:44:42to confer this diversity of the microbiome.
0:44:45 > 0:44:48One research trial has found that giving probiotics to babies
0:44:48 > 0:44:52reduced their chance of developing eczema at two years old.
0:44:54 > 0:44:57But others have found they make no difference.
0:44:59 > 0:45:02Whether they may help chronic health problems like allergies
0:45:02 > 0:45:03remains to be seen.
0:45:06 > 0:45:10Well, I don't think that prebiotics or probiotics can cure an allergy.
0:45:10 > 0:45:13I think they can help prevent against infections.
0:45:13 > 0:45:17I think the most important point is that the microbiota,
0:45:17 > 0:45:21if it's diverse and healthy at an early stage in life when the
0:45:21 > 0:45:23immune system is developing,
0:45:23 > 0:45:26then you can prevent allergies occurring.
0:45:26 > 0:45:29I doubt very much if these kinds of products can actually cure
0:45:29 > 0:45:30existing allergies.
0:45:36 > 0:45:41Surprisingly, one hope for helping those with allergies in the future
0:45:41 > 0:45:45may lie in actually replacing your gut bacteria with someone else's.
0:45:46 > 0:45:50This is exactly what doctors are doing to treat the aggressive
0:45:50 > 0:45:53gut infection, Clostridium difficile,
0:45:53 > 0:45:56and they're doing it with human faeces.
0:45:59 > 0:46:04Well, the sample is weighed first, and then gently homogenised.
0:46:06 > 0:46:10And this is then...sieved, for a better word...
0:46:10 > 0:46:12double-sieved.
0:46:17 > 0:46:21The faeces is processed in an anaerobic, or oxygen-free, chamber
0:46:21 > 0:46:23to mimic the inside of the gut.
0:46:25 > 0:46:29And after it's sieved, the volume is then topped up to the maximum,
0:46:29 > 0:46:32so as to leave no air spaces in the bottle.
0:46:35 > 0:46:39This healthy donor faeces is then transplanted into the patient,
0:46:39 > 0:46:44replenishing their bacteria and curing up to 90% of infections.
0:46:48 > 0:46:51It's early days and there's been no research into this technique
0:46:51 > 0:46:55for allergies yet, but it may lead to a treatment in the future.
0:47:02 > 0:47:06In the meantime, if we're to combat the allergy epidemic,
0:47:06 > 0:47:10we must reduce our risk of becoming allergic in the first place
0:47:10 > 0:47:13by re-engaging with the bacteria that's around us.
0:47:14 > 0:47:20But we must do so carefully because not all bacteria are good bacteria.
0:47:25 > 0:47:27So germs are everywhere in our home,
0:47:27 > 0:47:30but there are places where we're more likely to find them.
0:47:33 > 0:47:37Professor Sally Bloomfield is trying to educate people how best
0:47:37 > 0:47:40to safely re-engage with the right microbes.
0:47:41 > 0:47:43So what I'm going to do is to prepare fried chicken
0:47:43 > 0:47:45and a salad to go with it.
0:47:48 > 0:47:53When you take a chicken, we know that probably up to 60%, 70%
0:47:53 > 0:47:58of the chickens are contaminated with either salmonella or campylobacter.
0:48:00 > 0:48:02This gel mimics those germs.
0:48:02 > 0:48:05So there it is, I'm going to chop it up on my chopping board
0:48:05 > 0:48:08into my saucepan.
0:48:09 > 0:48:13Right, so what I want to do now is I want to prepare the salad.
0:48:18 > 0:48:23We may not be aware of it, but as we go about our daily lives,
0:48:23 > 0:48:27our hands come into contact with all manner of surfaces,
0:48:27 > 0:48:33something that becomes evident when Sally turns off the lights.
0:48:39 > 0:48:42The gel, which was invisible when we put it on the chicken,
0:48:42 > 0:48:44now we can see it glows under ultraviolet light.
0:48:44 > 0:48:47We can see exactly where the germs have gone.
0:48:47 > 0:48:49We have a look at the chopping board,
0:48:49 > 0:48:53you can see that even though we tried to clean it by wiping it
0:48:53 > 0:48:56with a cloth, there's still lots of germs on the surface
0:48:56 > 0:48:57and on the knife.
0:48:57 > 0:49:01Both of my hands are heavily contaminated with the germs.
0:49:01 > 0:49:04I wiped my hands on my pinafore
0:49:04 > 0:49:07and you can see I put it on my face,
0:49:07 > 0:49:09so I've even got germs on my face.
0:49:09 > 0:49:11And of course, the result of all of that is that you can now see
0:49:11 > 0:49:14there's plenty of germs have gone into the salad, and remember,
0:49:14 > 0:49:16that's going to be eaten raw.
0:49:25 > 0:49:29As Sally's demonstration shows, if we're not careful,
0:49:29 > 0:49:33we can very easily re-engage with the wrong type of bacteria.
0:49:35 > 0:49:39So good hygiene is about recognising that there are certain
0:49:39 > 0:49:42superhighways by which germs are spread,
0:49:42 > 0:49:45and by which we become exposed to them,
0:49:45 > 0:49:49and targeting our hygiene at those surfaces at the right time.
0:49:51 > 0:49:54From thoroughly washing everything after cooking...
0:49:56 > 0:49:59Where you can, rinsing germs away with running water.
0:49:59 > 0:50:03And where you can't, using antibacterial sprays,
0:50:03 > 0:50:06to using and binning tissues and washing your hands
0:50:06 > 0:50:08after going to the loo.
0:50:08 > 0:50:10There we go, let's get that under there.
0:50:10 > 0:50:12Or before you eat.
0:50:16 > 0:50:20But we needn't apply this level of rigour to every aspect of our lives.
0:50:21 > 0:50:23Look where you're going!
0:50:27 > 0:50:30The challenge is to find a healthy balance.
0:50:30 > 0:50:31Pedal!
0:50:31 > 0:50:36One where we nurture our good bacteria whilst protecting ourselves
0:50:36 > 0:50:39from harmful micro-organisms that cause disease.
0:50:39 > 0:50:41Cover your brakes.
0:50:42 > 0:50:44So it's not about whether we're clean.
0:50:44 > 0:50:48It's about the fact that we've become afraid of getting dirty,
0:50:48 > 0:50:51of going out and engaging with our microbial world.
0:50:53 > 0:50:55- Morning! - CHILD:- Morning!
0:50:56 > 0:50:57I'm on TV!
0:50:58 > 0:51:00Right, OK, so let's get your bike.
0:51:00 > 0:51:02HE RINGS BELL, HE SQUEAKS HORN
0:51:04 > 0:51:07Horizon's experiment is coming to an end.
0:51:10 > 0:51:14And as our families relive their experience,
0:51:14 > 0:51:17Lindsay has one final finding to share with them.
0:51:22 > 0:51:24One which proves just how disconnected
0:51:24 > 0:51:26from the microbial world we've all become.
0:51:32 > 0:51:36We put GPS on all of you, and we followed you for 24 hours
0:51:36 > 0:51:40to see how much time you spent indoors and outdoors.
0:51:41 > 0:51:44This graph shows the 20 hours and 58 minutes
0:51:44 > 0:51:48that Danny spent indoors in one day.
0:51:48 > 0:51:53We figured out that it was about 85% of your time spent indoors.
0:51:53 > 0:51:56But that's normal. There was a study done a couple of years ago
0:51:56 > 0:52:00that showed that on average we spent about 90% of our time indoors,
0:52:00 > 0:52:02which we don't really think about, do we?
0:52:02 > 0:52:05I pretty much live most of my life indoors,
0:52:05 > 0:52:06my work dictates that.
0:52:06 > 0:52:08So that's the hours of commuting,
0:52:08 > 0:52:11probably popping out at lunch
0:52:11 > 0:52:13and then back in the office until I leave.
0:52:13 > 0:52:16- Yeah, for your hunter-gathering? - Yeah, that's about it, yeah.
0:52:18 > 0:52:21But this indoor lifestyle has consequences
0:52:21 > 0:52:23for the diversity of our microbes.
0:52:25 > 0:52:29The swabs our families did of their TV remotes, kitchen tables
0:52:29 > 0:52:32and floors, shows that these surfaces are covered in skin
0:52:32 > 0:52:36and gut bacteria like staphylococcus and bifidobacteria.
0:52:43 > 0:52:46You live inside, you share those bacteria with each other
0:52:46 > 0:52:48and then you share it by kind of, you know, touching something
0:52:48 > 0:52:51and then someone else comes and touches it and picks it up,
0:52:51 > 0:52:53and just by personal contact and stuff as well.
0:52:53 > 0:52:57And if we're inside, then we're all just sharing what we've got indoors.
0:52:57 > 0:52:59And if you're outside,
0:52:59 > 0:53:02you start to pick up a bit more kind of environmental bacteria.
0:53:04 > 0:53:06For personal trainer, Paul...
0:53:06 > 0:53:09And jump! Yeah, good boy.
0:53:09 > 0:53:12..spending a lifetime outdoors does seem to have had
0:53:12 > 0:53:14an impact on the diversity of his bacteria.
0:53:15 > 0:53:17Look where you're going.
0:53:17 > 0:53:20Really interesting, Paul, that you had loads of environmental
0:53:20 > 0:53:25bacteria on your skin, but we also, when we did swabs of inside,
0:53:25 > 0:53:28there was loads of environmental bacteria inside your house as well.
0:53:28 > 0:53:31So you're obviously picking it up outside with your work
0:53:31 > 0:53:33and then bringing it in and spreading it around.
0:53:36 > 0:53:38However, as Morgan's allergies demonstrate,
0:53:38 > 0:53:43no one factor is able to answer what's behind the allergy epidemic.
0:53:43 > 0:53:45Though genes are important,
0:53:45 > 0:53:48it's becoming increasingly clear that changes
0:53:48 > 0:53:51to our environment may also hold the key to the rise in allergies,
0:53:51 > 0:53:54and as scientists around the world start to discover
0:53:54 > 0:53:56exactly what these changes are,
0:53:56 > 0:54:00it's giving hope for children like Morgan in the future.
0:54:01 > 0:54:04I worry so much about his asthma, running around too much
0:54:04 > 0:54:05and overexerting himself.
0:54:05 > 0:54:08Definitely taking that away with me, that I need to sort of
0:54:08 > 0:54:12encourage him to be outside a hell of a lot more than what he is now.
0:54:12 > 0:54:13Coming ready or not!
0:54:20 > 0:54:24I think we live too much of a chemical life now, really.
0:54:24 > 0:54:27Going back to being a bit more natural, being outside,
0:54:27 > 0:54:28climbing trees.
0:54:31 > 0:54:34We need to go a bit further back to that as we can
0:54:34 > 0:54:36in this sort of modern world.
0:54:38 > 0:54:41I hope that we can take what we've learned today
0:54:41 > 0:54:45and hope to improve Joe's lifestyle in any way which we can,
0:54:45 > 0:54:49and also the other families that are suffering in the same way too.
0:54:59 > 0:55:02Look, we may be able to pull this off like that.
0:55:02 > 0:55:03How about that?
0:55:03 > 0:55:06Is there anything there?
0:55:09 > 0:55:12Like our families, perhaps the best thing all of us
0:55:12 > 0:55:15can do to improve our microbial health is simply reconnect
0:55:15 > 0:55:18with those old friends that we evolved with.
0:55:18 > 0:55:21That's your idea of big, is it, Emma?
0:55:21 > 0:55:23This is Harry, the cocker spaniel.
0:55:25 > 0:55:27Harry! This is brilliant.
0:55:27 > 0:55:29He's helping his proud owners,
0:55:29 > 0:55:32Graham Rook's grandchildren - Emma and Ollie -
0:55:32 > 0:55:33to find bugs and beasties.
0:55:33 > 0:55:37Wonderful. Thank you, Harry. That's a huge beast.
0:55:37 > 0:55:40There's got to be a bug under there.
0:55:40 > 0:55:42Oh, look, that little centipede.
0:55:42 > 0:55:45We've got two millipedes and lots more woodlice.
0:55:45 > 0:55:47And these little guys.
0:55:48 > 0:55:52Digging in the dirt is admittedly more of a canine pastime,
0:55:52 > 0:55:54but we could learn a thing or two from Harry.
0:55:56 > 0:56:00Well, we just saw Harry, for reasons I am unable to understand,
0:56:00 > 0:56:01digging holes.
0:56:01 > 0:56:05You know, I mean, he's got to pick up all sorts of interesting organisms
0:56:05 > 0:56:06from the environment there.
0:56:08 > 0:56:11He's managed to get some gubbins onto the lens.
0:56:13 > 0:56:17Studies suggest that reconnecting with bacteria in the natural world
0:56:17 > 0:56:18is good for our health.
0:56:20 > 0:56:22Ooh, you finding anything else?
0:56:25 > 0:56:29We can't all have dogs, but there are other ways to re-engage with
0:56:29 > 0:56:34green spaces, no matter how small they may be.
0:56:37 > 0:56:40Well, first we need to know more about what the ideal
0:56:40 > 0:56:43small green space would be, and what are the right plants
0:56:43 > 0:56:47to have in it to encourage the right micro-organisms and so on.
0:56:47 > 0:56:49Oh, look, there's a millipede.
0:56:49 > 0:56:53It might mean then that to get the health benefit of green space,
0:56:53 > 0:56:57you don't have to have places the size of Richmond Park here.
0:56:57 > 0:57:00It might be possible to have much smaller green spaces
0:57:00 > 0:57:04that are specifically designed to contain and release
0:57:04 > 0:57:08into the environment the right micro-organism.
0:57:08 > 0:57:11It'll come. You know, there are going to be ways ahead for all of this.
0:57:11 > 0:57:15Come on, let's go for a walk.
0:57:20 > 0:57:23Scientists may still be on the cusp of understanding precisely
0:57:23 > 0:57:25which bacteria we need to reconnect with.
0:57:25 > 0:57:27Hey, what sort of poo is that?
0:57:27 > 0:57:31But Graham has no doubt about how important they are for our health.
0:57:38 > 0:57:41There are still of course a few people left on planet Earth
0:57:41 > 0:57:44who think of humans as some sort of plastic creature
0:57:44 > 0:57:48that arrived from space, and was plonked onto a world
0:57:48 > 0:57:51and is completely separate from that world, but of course we aren't.
0:57:51 > 0:57:54We evolved within this biosphere.
0:57:54 > 0:57:56We are a part of this biosphere,
0:57:56 > 0:58:01and in a way this realisation that humans are in fact ecosystems
0:58:01 > 0:58:05and that we depend so much on these micro-organisms is probably
0:58:05 > 0:58:09the most important advance in medicine in the last hundred years.
0:58:09 > 0:58:12I would regard it as more important in a way than
0:58:12 > 0:58:15the solving of the genetic code.
0:58:15 > 0:58:19For a start, most of our genes are not human anyway.
0:58:19 > 0:58:20Come on, then!