In this episode of The Referral, Dr Karan welcomes Dr Blair Merrick, Clinical Research Fellow in the Faecel Microbiota Transplantation (or FMT) unit based at Guy’s and St Thomas NHS Foundation Trust. Listen closely, as the two doctors discuss poo transplants, YES POO TRANSPLANTS, and give YOU the take home’s for your healthiest gut, yet! 



Karan also brings you ‘What The Health’, the latest in health and science in the news, and he answers YOUR questions in ‘Crowd Science’. 



If you have a health-related question and want to get in touch, just head to TheReferralPod.com. 



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2 of the most precious things that we have in this day and age is time and money, and often for a lot of people, we are wasting them both.

That's why this podcast is going to hopefully save you time, save you money, and give you actual evidence-based science so you can live your life in a better way and hopefully keep your wallet nice and full.

This is The Referral, a brand new health and science podcast with me, Dr.

Everything that you hear online that's not evidence-based, I'm going to be cutting through the bullshit and especially in this episode real crap.

On today's show we have Dr Blair Merrick.

He's a clinical research fellow and also coordinator of the Fecal Microbiota Transplantation Ferraro trial in very simple terms, poo transplants, taking poo from 1 person and chucking it inside another person.

Keep watching if you want to find out if you have good gut bugs, if you are a super pooper, if you want to find out all of that, keep watching and I'll tell you the tips how you can become a God level pooper.

We now are kind of understanding that the kind of bacteria and other things in our guts are intimately linked to our overall health.

Every day in the hospital as a doctor and surgeon, I constantly get asked questions from patients and staff as well.

And that's why I'm going to be opening the floor to my guest to ask me questions while I'm, you know, knuckle deep inside her.

She says she turns around, she looks at me and says, I follow you on Instagram and you at home.

If you want to get in touch and ask a burning question, you can get in contact at thereferralpod.com.

Also in the run up, if it ducks like a quack, this is my favourite segment, I'll be debunking and demystifying all of the bullshit, forgive the pun, myths that you're gonna hear today about poo.

You have a massive dump which makes you feel incredible afterwards, that's probably not good because you're probably not going enough.

What the health is going on in the world of health, science and medicine?

You're going to want to listen to this, because this is all about how to reverse your age if you've got millions to spend.

What if I told you there was a man who was trying to get the rectum of an 18 year old?

And to achieve that, he's spending $2 million a year and he's recruited a team of 30 scientists to optimize every facet of his life.

So he's worth around 400 million so clearly he's got a lot of money.

Some of the things include exercising for an hour a day.

Now that's not gonna reverse your age but certainly delay neurodegeneration, loss of muscle, loss of bone density.

So that is a proven anti-aging or at least delaying aging therapy.

He's got a vegan diet with precisely 1977 calories that has no proven benefit but certainly if someone is significantly overweight reducing calories can help to improve their metabolic profile and may help to improve their blood markers and maybe prolong their life.

He also goes to sleep and wakes up at exactly the same time every day.

Now I've always gone on about the importance of a sleep routine.

Waking up and sleeping at the same time every day is crucial for developing a good sleep habit.

Now this next 1 is highly spurious and actually quite dangerous much like a lot of the stuff he does.

It's a lot of pseudoscience and not really based in much evidence.

So he's aiming to infuse the plasma from his 17 year old son into his body to give him some sort of youthful look and eternal life essentially.

Now plasma exchange and plasma therapy is used in some liver conditions, blood clotting conditions and even burns but it's not proven as an anti-aging therapy and in fact it can be downright dangerous.

Now this is based on some science but in humans it doesn't really add up.

There were some gruesome studies done on mice where they took younger mice and stitched them to older mice.

Literally stitched them together so they were 1 big giant mega rat and there were some markers in improvements in cognition and circulation seen in the older mouse because it shared some of the circulation from the younger mouse.

Now we know that mice studies and rat studies don't always translate to humans so don't stitch yourself to another human being and don't take young blood from another human being.

Okay, so Neurosurgery, brain surgery, is complex to say the least, but imagine if your patient was still inside the womb.

Yep, surgeons have successfully performed the first ever brain surgery in a fetus inside the womb.

The fetus was just 34 weeks old and the surgeons used ultrasound guidance to help them access the brain.

The fetus they were operating on was diagnosed with vein of Galen malformation.

Now this is the geeky science bit for all you science lovers out there.

Basically your arteries join onto your veins but in the middle they have to go through capillaries.

The role of the capillaries is to almost buffer and slow down the blood so it reduces your blood pressure.

In vein of Galen malformation, the arteries just plug in directly into the veins without those capillaries.

So you still have that really high blood pressure going into the veins.

So that person can suffer with heart and lung issues like heart failure.

And in some cases it can be life-threatening.

Following surgery, the child was born and so far there seems to be no abnormalities in their growth at all.

This was done as part of a trial, but proof of concept here that it worked and this could be used for way more congenital malformations and other high-risk procedures which could be life-threatening.

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Fun fact, the cells in your intestine contain tiny biological clocks that influence what time of the day you want to go for a poo.

Today, we're going to be talking all about the grisly, stinky world of poo and specifically, poo transplants.

Now, some people are absolutely disgusted by poo.

Some people love talking about poo and some people think that their shit doesn't stink.

He's a clinical research fellow at the Fecal Microbiota Transplantation Unit at Guy's and St Thomas's Hospital.

Blair, thank you very much for coming on the podcast.

Will Tell me how and why you became a poop scientist.

Blair O'Brien So I'm a doctor by background.

My training is in infectious diseases and general medicine and kind of from that I have then taken time out of training and the projects that are kind of available to do research in, well, faecal microbiota transplantation was 1 of them and the reason is is that St Thomas's Hospital is 1 of these units that manufactures faecal microbiota transplants or FMT, administers them to patients and also is involved in research studies.

There aren't many units across the UK that do that.

And there's this huge, almost hidden world of people doing DIY microbial transplants, you know, sort of getting their friends or families poops and somehow getting it inside them.

But for anyone who doesn't know what we're talking about when we talk about poo transplants, breaking it down very simply, it's nowadays can it's a ground up or sort of dried ground up faeces that contain good bacteria potentially and given in either a capsule form, a crapule, or a colonoscopy?

Yeah, those are the 2 kind of main delivery methods.

Essentially, I mean it's all in the name, faecal microbiota transplantation.

So faecal, it's derived from faeces, stool, poo, crap, whatever you want to call it.

Microbiota is essentially the term given to all of the living organisms in a particular area.

So in feces, we're looking mainly at bacteria, but also viruses, fungi, parasites, all sorts of things.

And the kind of small molecules they produce, the metabolites.

And then transplantation, taking it from 1 person and giving it to another, hopefully a healthy person and giving it to somebody who has a problem that we can make better.

We essentially from the faeces want to get rid of kind of the stuff that we don't want which is mainly the undigested food and in the case of capsules we want to get rid of basically all of the water because with the capsules you obviously want to minimise the number that you have to take.

So the initial capsules were what we call wet kind of capsules and people would have to take maybe 25 capsules.

We've developed at St Thomas a lyophilized form, so that's freeze-dried, so we've taken out all the water and we've kind of got it down to about 5 capsules, that's kind of 1 treatment.

Key question, what colour is the capsule?

the capsule officially is Swedish orange, Although in a study that we've recently done where we asked kind of participants about their experiences of participating in the study and about their experience of taking FMT, they thought it was kind of a joke because the orange isn't very orange, it's more brown and so they were like, is this some indication of kind of what we're taking?

No, the reason that we use that colour is that you, for studies sometimes we use a dummy medication, a placebo, and we needed to make sure you couldn't see through the capsule to see which 1 was the real thing and which 1 was...

And also the Swedish orange colour is vegan and we didn't want that to kind of preclude people from participating because it, you know, there was maybe animal products or something in the capsule.

And then we didn't really think about the colour too much until our participants mentioned it.

Will Barron I think, considering that the microbiome has far more genetic data than our human genome, and considering that we are more microbiome than human cells, sort of 1 to 3 ratio, potentially, that's what it's sort of, or 1 to 1 at least, they influence a considerable part of our health, our morbidity risk, our disease risk, all these sort of things.

But using this same mechanistic theory that, okay, the microbiome has this amazing potential to cure all sorts of diseases, we're seeing a lot of pseudoscientists trying to peddle microbiome-related things or bespoke microbiome, probiotic pills or this and that, kind of abusing the power of the microbiome to sell things.

Do you see a lot of your patients on these probiotics that they buy in shops or things like that?

Yeah, we do see a lot of that and we get a lot of requests to kind of have off-label treatment with FMT.

Now, you know, you know, big statement, you know, fecal transplants are not going to suddenly be a cure-all for a whole wide range of conditions and even conditions in which we know that people's kind of gut microbiome is, you know, abnormal or dysbiotic is a term that's often used.

But as you kind of alluded to, we now are kind of understanding that the kind of bacteria and other things in our guts are intimately linked to our overall health.

Rather worryingly, the kind of diversity of all of the organisms in our gut seems to be kind of decreasing generation on generation.

And that's probably through a multitude of factors.

That's probably partly related to our diet, the fact that we're using antibiotics more, which as well as kind of maybe treating infections, you might be suffering from also kind of kill off the good guys in your gut.

And then just medications in general will often have an effect, not just the antibiotics.

mean you get your first dose of your microbiome from your mother.

So babies that are born by cesarean section have a different microbiome to those that are born vaginally and those differences can be seen even up to 1 year of age and maybe beyond.

As individuals are kind of more commonly being born by caesarean section and we're seeing more of these changes that's kind of 1 theory as to why kind of some non-communicable diseases like allergies might be becoming more common.

Will More urbanisation, less diversity, exposure to animals, farms, things like that.

And so we need to probably find the right balance between kind of exposure to kind of good bacteria and other things in the environment and making sure we keep our microbiomes as diverse as possible, as well as staying healthy from obviously not, you know, getting nasty infections.

Yeah, I think, I think 1 of the scariest things that you've mentioned there was basically that we are experiencing an extinction level event for certain species of bacteria in our guts, which is worrying because we're not, we seemingly we've not changed much, but we have over thousands of years.

Modern day hunter-gatherers, the Hadza tribe in Tanzania, I read in a study that they have around 30% of their microbiome are novel species of bacteria that we haven't seen in other populations, which suggests to me exactly what you were saying, that the stresses of modern life and maybe the vices of modern life, ultra-processed foods, stress, emails, bosses, all these sort of things, maybe more of a sedentary lifestyle, not enough exercise, less whole food consumption, all these sort of things.

And maybe all of these other peripheral things like poor sleep, et cetera, et cetera, are culling the bacteria that we have.

And like we mentioned before, these bacteria are intimately linked with various bits of our health, immune system, gut health, etc.

So we are, in some senses, worsening our health, and we can't even see it.

Yeah, that's the scary thing about it is, it's all happening inside us, but there's often not really any symptoms of it, or maybe only many years down the line, like these kind of autoimmune conditions or allergies and things take many years to develop.

And we maybe only see it kind of through generations that slightly more people are getting these problems, you know, kind of generation on generation.

And what's the kind of difference, you know, between that generation and the 1 before?

Well, a big part of it might be the diversity within our guts.

So I mean, in my day-to-day job, I'm seeing people with inflammatory bowel disease, other gut issues, irritable bowel syndrome, and the things I usually tell them about improving gut health, I keep it very simple, I don't tell them to take probiotics, you know, basically like, you know, papering over the cracks.

I suggest things like increasing exercise, which has been known to improve the composition of your gut microbiome favorably.

Making sure you have a fiber-rich diet that's more plant-heavy rather than meat-heavy, because from studies it's been shown that high quantities of red meat can worsen the mix of gut bacteria and, you know, sort of cause increasing inflammation.

But also avoiding unnecessary antibiotics, you know, if you've got a cold or flu that's likely to be viral, not just to pop some antibiotics you might have in your kitchen drawer.

NSAIDs, non-steroidal anti-inflammatory drugs, can also disrupt the microbiome, alcohol, things like that.

Is there anything that you've seen from the clinical data and the patients that you see in these trials that suggest that these are things that the average person should be doing to improve their gut microbiome makeup?

Well, I think all of the things you mentioned, yeah, really important.

And they're all achievable things, I think, for most people to do.

And I think the really important thing is that it's small things that are sustainable because there's no point doing, with your gut health, there's no point doing something for a week, a month, or even a year.

It's about making a change to your lifestyle that's sustainable over many years, decades.

And big things aren't generally sustainable.

Yeah, I mean, agree with all the things that you said, probably adding into that, making sure that you're kind of well hydrated.

So most people probably don't drink enough, and probably the, cheers to that, and the other thing would be maybe the addition of some fermented foods.

So things like kefir, kombucha, kimchi, a little bit of that, and that probably, kind of fermented foods were part of our diet a bit more in kind of years gone by when we didn't have the preservation techniques like the fridge and the freezer.

So even simple things like cheeses, stuff which were the bacteria have already gone to town on basically.

And yeah, you don't need to buy probiotics.

You know, they're often expensive and might be beyond the reaches of individuals.

And with regards to your diet, it's really about diversity.

It's about can you kind of introduce as many different things into your diet in kind of a good balance.

Different colours, which have different antioxidants, polyphenols and nutrients.

And then, yeah, any kind of starches you're having, if you can introduce whole grain ones, as opposed to kind of white ones.

So whole grain bread, whole grain pasta, keep the skin on potatoes.

Skin on fruit, skin on potatoes, skin on veg as much as you can, right?

It's these core habits rather than relying on probiotics to basically boost your health.

It's about getting enough exercise, getting enough sleep, 30 grams of fibre a day, a range of fibres as well, you know, nuts, seeds, plants, etc.

And, you know, going back to the point of exercise, you know, it's been shown that as little as 10 minutes of exercise a day is associated with a health benefit.

You know, that's, I think, something that, you know, everybody who's, you know, even anybody who's sedentary can kind of introduce that into their lives, whether that's taking the stairs or walking or cycling to work or part of their journey, those sorts of things.

It's about integrating it into your daily life and sticking with it for the long term.

I mean, if I look at the role of the microbiome, and we know it's well established that your gut is very closely connected, probably as connected to your immune system as anywhere else in the body, in your guts.

And we know that your microbiome has a role in training your immune system as well.

A lot of these proponents of the kind of gut-brain connection suggest that, you know, part of the development of these neurodegenerative conditions like Parkinson's and Alzheimer's, maybe in part related to abnormal microbiome conditions and dysbiosis, same with some bowel cancers, etc.

And if you actually look at the current state of affairs, just within the last 12 months, you've had in the cancer world, you've had Dostalimab, which is a monoclonal antibody, which has proven to cure locally advanced rectal cancer without chemotherapy and surgery, published in the New England Journal, just 16 to 18 patients, and also leucanumab, the new drug for Alzheimer's, first ever drug for Alzheimer's shown to slow down the disease process.

And those obviously modulating the immune system.

So clearly there is some blueprint and some path there, suggest that if we can find out really how the microbiome works, because we've completely sequenced the entire human genome, but we've only sequenced a fraction of the microbiome.

Yeah, there's still lots there that we, that kind of comes out as being unclassified.

So I think there's a whole world out there of microbiome research.

But for now, I would say that from the takeaway to if you want to be somewhere near a super pooper is to do the small things like we said.

I don't know if I'm going to get myself into trouble here, but fire away, please.

So, you've obviously got a, you know, a presence on TikTok, social media.

And I just wondered, as a healthcare professional, kind of what's been your experience of that, both kind of good and also bad?

I'll tell you 1 story, change a few details.

1 Friday morning, I drew the short straw and I had to do the hemorrhoid banding clinic.

So I think someone, the rota person didn't like me.

So naturally you see all these patients with haemorrhoids and you band them.

So banding a haemorrhoid, for anyone watching, involves inserting a, what is essentially a bum gun that fires a high speed elastic band onto the haemorrhoid and the haemorrhoid loses its blood supply and then falls off.

She comes into the clinic, very pleasant, brought in a chaperone and first thing before I decide to bandage I need to examine the haemorrhoid and see how bad it is.

And obviously, part of the examination requires you to do a digital rectal examination.

I have to pass a gloved finger into the patient's bottom and have a feel.

Interestingly, I tell her how to get into the position.

She gets on all fours and just says, you know, examine their bottom.

I'm examining her bottom, chaperones here, okay, just to cover myself.

While I'm, you know, knuckle deep inside her, she says, she turns round, looks at me.

Right, rule number 1, unofficial rule number 1, and no talking either, rule number 2, Right?

She looks at me and says, I follow you on Instagram.

And you know, rule, number 1 rule actually of doing rectal examinations, never say thank you.

I said, okay, thank you, I guess, whatever.

Finished exam, fired a rubber band onto a hemorrhoid.

She sat down and I didn't really know what to say.

I guess, you know, follow and like for more.

I had to be even more friendly than I had to usually am with patients, and even more, oh God, you know, she follows me online and she knows everything about me.

So the moral of that story is that in terms of being a healthcare professional online, there's sometimes a very thin veil between your personal life, your kind of social media presence, and then being a professional in a hospital capacity.

But I would say the positives significantly overweigh the negatives and it provides you with a platform to make change almost on an epidemiological level.

When you've done a clinic, you know, we'll see what, 10 patients in 2 or 3 hours?

But if you make a video that gets 2 or 3000000 views, you're potentially impacting a lot more people who can take away some information about how can I deal with constipation or how can I deal with this abdominal pain that I've got or what do I need to look out for?

So I find that quite rewarding that you can reach a lot more people who may not have the same access to healthcare as someone in a different country.

Big, big reach to people you've never met, which is kind of amazing really as a healthcare professional to be able to do that.

Blair, thank you very much for coming on.

And you know, if anyone has a desire to send their excrement to someone, please do not send it to the referral HQ.

Blair Merrick, Please inundate him with your poo parcels and we'll leave a little note as to where people can direct their specimens to.

Yeah, we're always happy to hear from potential stall donors.

So It's legal to send your poo in the mail for science.

This is 1 of my favourite segments of the show.

It's where I'm going to be debunking all of these terrible myths that you hear.

And 1 of the worst ones that I hear all the time, you should poo every day.

Everyone has their own individualised intestinal transit time.

This means it's the time taken for the food to transit the entire intestinal tract, the small intestine and the large intestine.

It could be anything from 18 hours to 24 hours or even beyond.

Now, there is a Goldilocks rule that I like to follow when it comes to bowel health.

Over, if you're going to the toilet more than 3 times a day, it's probably a bit too much.

And if you're going less than 3 times a week, that's probably pushing you towards the side of constipation.

So between 3 times a day and 3 times a week, that is in the normal range.

So don't listen to anyone that says you need to poo every day.

If you do great, if you don't, you need to look out for some of the other symptoms that could be a sign of constipation.

You're going less than 3 times a week and you feel that you still need to empty your bowels even after you've gone or you have a massive dump which makes you feel incredible afterwards that's probably not good because you're probably not going enough but apart from that pooing every day is not a must.

Now another thing I've often heard people say, if you've eaten too much and you want it to digest as quickly as possible, you lie on your left hand side.

There is some morsel of truth to this, not in terms of the digestion, but why it could be helpful.

Now, it takes around 90 minutes for 50% of your stomach contents to empty into the small intestine.

So if you've had a large meal at say 8pm, you probably don't want to be going to bed immediately.

You want to probably at least wait an hour and a half or so so your stomach is emptied a little bit and so it can reduce your risk of acid reflux if you do that.

If you lie on your left hand side, in that position your stomach is actually in a lower position than your esophagus, your food pipe, so there's less chance of acid reflux, of stomach contents going back up into the esophagus.

And again, you'll reduce your risk of acid reflux.

If you suffer with acid reflux, this might be a nice strategy to try, But otherwise, stick with the other concept first and leave a bit of a gap after eating your last meal of the day and before going to bed.

Now this is 1 of the banes of my existence as a GI surgeon.

This is 1 of the worst things that I see and it's a modern day scam.

Now, when it comes to gut health, I found it very hard to believe that a 1 size fits all probiotic that you can buy in your local supermarket can fix everyone's gut health, considering that everyone has an individual microbiome that is as unique as your DNA.

See all The Referral with Dr. Karan transcripts on Applepodcasts

Microbiome Expert: Daily Habits That Are Destroying Your Gut Health