Global News Podcast - The Global Story: Have we already found the fountain of youth?

Episode Date: January 26, 2025

For centuries, people have pursued the dream of eternal youth. Researchers have been making progress in understanding what happens in our bodies as we age. We may soon be able to use drugs to slow or even reverse ageing.

This BBC podcast is supported by ads outside the UK. Discover how to lead a better life in our age of confusion. Enjoy this BBC audiobook collection, written and presented by bestselling author Oliver Berkman, containing four useful guides to tackling some central ills of modernity. Busyness, anger, the insistence on positivity and the decline of nuance. Our lives today can feel like miniature versions of this relentless churn of activity. We find we're rushing around more crazily than ever. Somewhere, when we weren't looking, it's like busyness became a way of life.

Start listening to Oliver Berkman, Epidemics of Modern Life, available to purchase wherever you get your audiobooks. books. Global Story wherever you get your pods and be sure to subscribe so you don't miss a single episode. Here's my colleague Lucy Hawkins. For thousands of years people have dreamt of and searched for the Fountain of Youth. It may have eluded the ancient Greeks and 16th century Spanish explorers and in the 20th century the idea of turning back the clock might have been resigned to science fiction. In recent years though, scientists have slowly but surely been understanding more about how our bodies age at a cellular level. And there's increasing evidence that some drugs might be able to reverse that process, giving humans

longer and healthier lives than ever before. What's more, you might already know people taking some of these drugs. So could we really drink from the fountain of youth in our lifetime? With me today, hopefully not to crush all of our dreams, is Dr. Andrew Steele, a scientist, campaigner and author of the book Ageless, the new science of getting older without getting old. Good to have you with us, Andrew. Hey, how are you doing? Andrew, I'd love to know when you meet people for the very first time and you say to them my work focuses on ageing. What sort of questions

do they ask you? Oh, kinds of things. I think one of the most popular is obviously what's the magic pill? Have you got one for me? Where can I sign up for the trial? But another question you get surprisingly often and this sort of shocks me in a way, or did initially at least, you get a lot of really complicated, naughty ethical questions. So people ask what about overpopulation? Haven't we already got a planet that's heaving at the seams with people and if we have people living longer aren't we going to have an even larger problem? And the reason I find that a bit strange is that I see it as just an extension of modern medical research. It's much the same as being a cancer researcher or a heart

disease researcher. You know, if I introduce myself at a party and say, hey, you know, I research cancer, everyone says, fantastic, it's brilliant, I really want to cure cancer. And yet if you talk about the idea of treatments for ageing, let alone a cure for ageing, people have a very different emotional, ethical reaction to it. And I find that absolutely fascinating. Andrew, this just might be a sign of how superficial I can be, but when I heard about us doing this podcast together and I thought about anti-aging, of course I thought about how I look. And I think a lot of people also, because of the success that the beauty industry has in marketing anti-aging treatments, that's where we go when we think about anti-aging.

But that isn't what we're going to be talking about today. What aspects of aging does your work focus on? Well, the idea is that actually those external cosmetic signs are clearly an aspect of aging. But the same processes that give us wrinkles, that give us grey hair, are also happening inside our bodies on a microscopic scale. And those processes massively increase the risk of disease. They increase the risk of cancer, dementia. All of these are called age-related diseases because the single biggest risk factor isn't smoking, isn't diet, it is ultimately the accumulation of the cellular, molecular damage and changes that go along with ageing. Say you're 30, you can have a terrible diet, you can smoke

and do all the wrong things health advice-wise, but you're still much safer from a sort of medical point of view than someone who's 80 and has led a completely clean lifestyle until that point because the risks that are associated with aging massively increase their risk of disease. But it's also the frailty, it's the incontinence, it's the impotence, it's all of this sort of constellation of things that go wrong with our bodies as we get older. And actually if you add up all of those different things, aging is responsible for more than two-thirds of deaths globally. And that's because of cancer, it's because of dementia, it's because of heart disease, it's because of the increased risk of dying of other things like infections as you get older. And if you add all of those together, you find that aging

is our single biggest challenge, I think. Andrew, why is it that all over my social media feeds at the moment, I'm seeing wellness experts and fitness people and beauty experts as well talking about their biological age. What do they mean? Well, that's because there have been advancements in the science in the last sort of five, ten years that have allowed us to come up with various measures of how old you are, not chronologically, so not how many candles are on your birthday cake, not how long ago you were born, but biologically. If we look down at these fundamental cellular and molecular changes, we can measure some of those changes and we can work out not just how old you are from

how long ago you were born, but also your risk of disease, your risk of frailty, all these other things added together. And actually one of the most popular are something called the epigenetic clocks. So to do one of these things you might do a blood sample or a saliva sample and then the scientists will test some markers on your DNA and we know that these markers change as you get older. When the scientists first did these experiments they were just trying to predict how old people were, see if you know they could even detect these changes. But what they noticed was that you know say I did an epigenetic age test I'm 39, if the scientists you know went

away and took my saliva sample and it came back as 45 they noticed that people with this accelerated epigenetic aging as it's called had a higher risk of disease, they had a higher risk of dying than people who this accelerated epigenetic ageing, as it's called, had a higher risk of disease, they had a higher risk of dying than people who had an epigenetic age that was equal to or less than their chronological age. Andrea, when I think about ageing, I think about my back and my knees that didn't used to be sore that are now, the fact that I'm starting to get grey hair, the wrinkles that are appearing on my face. That's what ageing means to me and I'm sure to a lot of people. But what exactly is it? I mean what is happening at a

cellular level? Well it's a variety of different things. We now know that aging isn't one single process and this is actually the reason we're never gonna have some single magic pill that allows us to just completely solve the problem. But what we understand is we can break it down into what are called hallmarks of the aging process. In my book I've got 10, some scientists say 9, some scientists say 12. There's a little bit of debate in the field but there's a broad consensus about what's going on there and so we can have a look at a few examples just to sort of make that a bit more concrete. The first hallmark is sort of the most fundamental, the smallest microscopic one which is looking at

damage to our DNA. Now our DNA as you know is the instruction manual that's found at the centre of every one of our cells but as we get older that instruction manual effectively's found at the centre of every one of our cells. But as we get older, that instruction manual effectively accumulates typos because there are various processes from the air that we breathe can actually damage our DNA, but when cells divide they have to copy that DNA and they can make essentially copying mistakes. And over time these tend to accumulate. And the most famous example of this is probably cancer, which is that if you accumulate enough damage, enough mistakes in your DNA, then eventually that cell forgets how to stop dividing.

And so it carries on dividing and dividing and dividing and eventually grows into a tumour and that's something that can kill you. We also think that other aspects of ageing are caused by damage to our DNA. If we zoom out a little bit further, we can see the fifth hallmark is what are called senescent cells. And senescent is just the biological word for getting older, it's sort of the technical term. And these are cells that have divided too many times, maybe they've got a bit of DNA damage,

they've got a variety of things wrong with them. What they do is in order to protect the body, they stop dividing. But unfortunately, when they stop dividing, they actually eventually accumulate in our bodies and can cause all kinds of damage that can go on to accelerate the aging process more broadly. And if we zoom out even further, the last hallmark on my list is the aging of the immune system. And I think we're all reminded of that, particularly starkly in the last few years because of the COVID pandemic. We know that older people were dramatically more likely to die if they got a COVID infection than a younger person was. But the immune system also has a variety of other roles around the body. It's not just for fighting disease. It also seeks out

cancer cells. It also actually clears out those senescent cells I was just talking about. So as the immune system weakens, it causes a whole range of other issues. And as you can see, just in these three examples I've given, these hallmarks are all very interconnected as well. The hope is, because these are the fundamental drivers of the ageing process, if we can go in and intervene in those, then potentially we can stop not just one, perhaps many or even all of the age-related diseases with a few treatments. Andrew, I found it really interesting that you describe ageing as the biggest humanitarian crisis facing us. How did you come to that conclusion?

Well, the first thing is just what I've already mentioned actually, the sheer number of deaths that it causes. So 150,000 people die every single day on planet Earth of a variety of things. But over 100,000 of them die of ageing. More than two two thirds of people die because of the cancer, because of the heart disease, because of the dementia, because of the increased risk of disease and so on. So what that means is that it's by far our largest cause of death. And actually in the rich countries it's even more extreme than this. In a country like the UK or Germany, about 90% of deaths are caused by the biological process of ageing.

So there's just no argument that this is our single largest cause of death. And as life expectancies rise globally, countries in the developing world are rapidly catching us in the rich world up. So that's the first thing, this huge, huge number of deaths. But it's the way those deaths happen here, maybe death's not so bad, you know, you don't have to be afraid of dying

to want to do something about this. It's because as you get older, there's this huge decline that comes along with it. You've already mentioned your knees and your back, but obviously these things get much, much worse. If you're in your 70s or your 80s, that frailty can really start to kick in and impact on your activities of daily living.

You can't get around the house, you can't go on holiday, you can't play with your grandkids, you can't engage in your hobbies. And then the way these diseases kill you is often drawn out and very unpleasant. With cancer, it can be years of grueling treatment before you finally die. And so I think aging is our greatest cause of suffering as well, not just death.

And that's why I think it's our greatest humanitarian challenge. There's just nothing else on the planet that causes this degree of suffering. And that means I'm hugely excited by the idea that we might be able to do something about it. I mean, I'm dreading that, Andrew, the fact that the pain I've got on my knees and my back now are only going to get worse as time passes. But I think we also have this notion that ageing and then death is inevitable. It's going to come to all of us. Is there a narrative though around ageing that is changing? Are we starting to think about it in a different

way? I hope so. And I think that ageing, you know, for a long time it has been inevitable. And I think it's been a very rational position for humans to adopt because we've seen that we age, our pets age, our friends, our families age, everything around us, even in animal objects, you know, your phone starts to get a bit slower after a few years of use because it's aging in various ways. It just seems like this natural process of falling apart but I think what's really changing, fundamentally driving this social change, is the scientific

change. It's the fact that we now understand so much more about what's going on in the aging process and this has happened in the last 10 or 20 years. This isn't something that's been going on for decades and decades. It's the fact that we now understand so much more about what's going on in the ageing process. And this has happened in the last 10 or 20 years. This isn't something that's been going on for decades and decades. There's really been a revolution in our understanding. And we've now got dozens of different ways that we can intervene. We can slow down, maybe even reverse ageing in the lab. You know, the data is still coming in. And because we've got these dozens of different ways of doing that, I think people are sitting up and paying attention and going, well, if you can make this mouse younger, why can't you do it for me? These changes happening

in our bodies at a microscopic and cellular level might feel beyond our grasp and beyond our ability to control. But next the research into drugs that might slow down ageing, drugs that some of us might already be taking. Discover how to lead a better life in our age of confusion. Enjoy this BBC audiobook collection written and presented by bestselling author Oliver Berkman, containing four useful guides to tackling some central ills of modernity. Busyness, anger, the insistence on positivity, and the decline of nuance. Our lives today can feel like miniature versions of this relentless churn of activity. We find we're rushing around more crazily than ever.

Somewhere, when we weren't looking, it's like busyness became a way of life. Start listening to Oliver Berkman, Epidemics of Modern Life, available to purchase wherever you get your audiobooks. You're listening to The Global Story from the BBC World Service. There's a fresh episode available as a podcast each weekday. Just search for The Global Story wherever you get your podcasts. Today I'm with Dr Andrew Steele. Now Andrew, I want to talk to you about how all of this research might be used to improve our lives. And there's a really interesting concept I've seen in some of your writing. Can you explain the difference between a lifespan and a healthspan? I think this word healthspan is really, really important because nobody,

and this includes the scientists working on the biology of ageing, want to drag out that period of ill health at the end of life. And so, you know, we don't just want to extend how long you live, but we want to extend how well you live as well. And that's this idea of healthspan. It's not just how long, but it's how long you spend free from disease. And the good news is that basically every way that we know of to extend lifespan also extends healthspan. So, you know, we can just look at this from everyday life. We know that if you exercise, if you eat well, if you don't smoke, all of these things will make you live longer. But they also extend that period of life in good health, you know, before you get sick at the end of life.

You can also look at an example of human centenarians. So these are people who lived over the age of a hundred and what you find is that the average person who lives beyond a hundred lives independently until they're 100 years old and what this shows us is there's something in their biology that isn't just extending their lifespan, it's not making them old and frail for an extra 20-30 years that you know more than the rest of us have to deal with. They're actually delaying the aging process by that period of time instead and so hopefully if we can come up with a way to bottle that, we're going to have potentially the ability to keep ourselves healthy for longer. I think that's what all of us really

care about. So now to the big question, what we all really want to know. How can this all be applied to actually slow down our aging? Well, the idea is that by looking in the lab at these various changes, we can come up with ways to intervene in those changes. And I think the most intuitive one to explain is actually those senescent cells that I talked about earlier. So these are cells, they're old cells essentially, they build up in our bodies as we get older and they drive a whole range of different diseases.

So scientists thought, well, if these things are growing in number as we get older, then maybe if we could clear some of those cells out, that could help. And so in the 2010s, scientists were looking for various different ways that they could clear out these cells. And they happened upon a couple of drugs. There's a drug called desatinib, which is normally used as a chemotherapy drug, and something called quercetin, which is a flavonol. It's sort of a sometimes used as a nutritional supplement normally found in fruit and veg. And they found that by combining these two things together, they could actually remove the senescent cells from mice,

but leave the rest of the cells of their body intact. And they found that by doing this, they essentially made the mice biologically younger by a number of different measures. So the first thing is they live a little bit longer, that's a good start, but these mice were acting in a younger way as well. So they actually send the mice to the gym

in these experiments, they do sort of an experiment in frailty. And the mice that have been given the drugs could run further and faster on the tiny mouse-sized treadmills that they used than the mice that were the same age that hadn't been given those drugs. They found that it improved their brain aging as well. I think a lot of us are rightly very scared of dementia

and cognitive decline as we get older. But they found that by giving the mice these senolytic drugs, they're called, they cleared out those senescent cells, and they actually made the mice more curious, which is when you put a mouse in a maze a young mouse is often quite curious, really wants to explore its environment. An older mouse might be a bit more anxious and a bit less willing to explore and by giving them these drugs they could rejuvenate some of that youthful curiosity. And finally I just really recommend that your listeners go away and look for some pictures of these mice online. The mice that have had the drugs versus those that haven't

or before and after shots because Because you do not need to be an expert mouse biologist to see. They just look fantastic. They look like different mice. They've got thicker fur, they've got less grey fur, they've got plumper skin, they've got shinier eyes, they've got less age-related weight gain. They just look younger and hopefully, you know, we can start putting these two trials in humans and create something that humans could be taking as well. So there's no drug currently, create something that humans could be taking as well. So there's no drug currently, Andrew, that's licensed to broadly treat aging,

but are there some that are showing promise? There definitely are, and I think it's gonna be a bit of a challenge at first to get a drug licensed for aging per se, because you have to demonstrate somehow that it makes people live longer and healthier. And that's gonna be a long trial, right? Humans live 70, 80 years or more,

and that means that particularly if your drug works, that trial is gonna take even longer. One of the drugs that's going to be a long trial right you know humans live 70 80 years or more and that means that particularly if your drug works that trial is going to take even longer. One of the drugs that's really showing promise in the lab is a drug called rapamycin and this drug has an absolutely fascinating backstory. It was first isolated in a soil sample from Easter Island that's the one with the massive stone heads people might have seen. They isolated this bacterium they found it produces this molecule called rapamycin and to cut a very long and fascinating story short, in 2009 scientists showed that you could give it to mice, you could even wait until the mice were pretty late in life, so they waited until they were 20 months old, about 60 years or

so in human terms, they gave them some rapamycin and they found that they made them live longer, maybe 10-15% longer in fact. And again, they weren't dragging out that period of frailty, they were keeping them healthier for longer as well. And what's really fascinating is that this is a drug that humans are already taking. They're not taking it in the longevity context but what they're doing is taking it as a transplant drug. So if you've had an organ transplant then one of the big risks from that transplant is that your immune system will recognize that that organ doesn't come from your body and attack it.

And rapamycin was actually first developed as a really effective immune suppressing drug. But it turns out if you take it at much lower doses, it might have an effect on lifespan. Now this probably isn't ready for the prime time, I don't think people should be going away and start popping back the rapamycin pills. We haven't got the proper randomized control trial data

I would like to see, before I start recommending this to people to actually take for aging. But the fact is, this is a drug we've been using for a couple of decades now. We understand its safety profile, we understand how it works. We've got really solid evidence that it works in the lab.

So we just need to start doing some more experiments and see if this could be used to slow down aging in people as well. I mean, these trials sound really impressive and I think people will find it exciting that the drugs already exist and are being used by humans, Andrew. But what are the difficulties in getting trials like this up and running? One of the big ones is just money, because these have to be big trials. There's a trial

that's been proposed for another drug that actually people are probably already taking. In fact, quite a lot of listeners might already be taking this, a drug called metformin. This is the first line therapy for type 2 diabetes, the sort of age-related diabetes that a lot of people get as they get older. And that means it's one of the most prescribed drugs in the world. In the UK it's been being prescribed since the 1950s. This is a real sort of classic of the pharmacopoeia. But what scientists have found is that it might slow down the aging process. And there was a trial proposed for metformin called the TAME trial. It stands for Targeting Aging with Metformin. And this was a trial where they get 3,000 people,

1,500 people take the drug, 1,500 people take an identical looking pill, but doesn't have any active ingredient called a placebo. And then you can watch those two arms of people and see if people in either arm, maybe they get ill later, maybe they die later, if that metformin is slowing down the aging process. Now metformin is essentially free,

that costs pennies per pill and that's because it's well out of patent, it can just be produced generically, we've known about it for decades and decades and decades now. But even though the drug essentially costs nothing, that trial would still have cost about 70 million dollars if it were funded. And that's not a small amount of money, that's not the sort of money that an academic institution can put up, it's the sort of money that a drug company might be able to put together. But the problem is that no drug company stands to profit, you know, imagine the TAME trial works and metformin is incredible and slows down human ageing, then unfortunately it's out of patent, so nobody can start churning

out metformin and making a load of money from it. And so that's a real difficulty. And that's actually where those biological age tests that we talked about earlier could really come into their own. Because if we can get to the point where rather than doing one of these really long trials, we can just measure everyone's biological age at the start, give them a drug that we're trying to test, and then maybe six months later measure their biological age again, we can improve it on the basis of that biomarker. Andrew, what other therapies are out there that people are getting excited about? I think one of the most exciting that's really causing a buzz at the moment is something

called cellular reprogramming. And this is a fascinating therapy. I'm actually a new dad. I've just had my wife and I've just had a baby. And this is a really interesting thing from a biological point of view. Thinking about it from the possibility of aging biology, then I'm 39, my wife's 33, and our baby is zero years old. Now, I know that sounds really obvious, but bear with me here. Babies who are born to 30 odd year old parents have the same life expectancy as babies who are born to parents in their 20s or even babies who are born to

parents in their teens. So clearly even though she was born from old cells, she was born from a 32 year old egg cell from my wife and a 39 year old sperm cell from me, somehow that combination has managed to reset the biological clock and she's got a normal life expectancy ahead of her. So in some ways, biology has already solved the aging process. The question is, can we somehow come up with a way to bottle that and give it to people? And in the lab, that has actually been achieved. We can do this process called cellular reprogramming, where we can turn back the biological clock of a cell.

And this was first used for stem cell research. You get a cell from my skin, for example, and turn back the clock and turn it into a stem cell that could then become any kind of cell in my body. But scientists noticed that while they were turning back the developmental clock on these cells, it also turned back the aging clock, or at least seemed to. And so they tried this experiment in whole mice.

They found that it didn't reverse the mice's cells all the way back to being stem cells. It just made them age a little bit more slowly. And there's huge, huge commercial interest in this now as well because it's such an exciting technology. The biggest sort of startup in this field is called Altos Labs, funded by amongst other people Jeff Bezos. And they've got three billion dollars to get there from investors to try and investigate this technology. This is also cool, Andrew, but the obvious question as well is when could this all be

a possibility? And this, I think, comes to a question of funding. I think the question that journalists love to ask and scientists hate to answer is how long is it going to be? And I think part of the reason for that is that thinking of it as a number of years away is the wrong way to think about it, because we have to actually try to get this research to work. And take the example of the US.

One of the few countries in the world that has an actual government research body specifically devoted to looking into aging biology and if you look at the aging biology division of the National Institute for Aging so this is the part that's doing the kind of research that I care about their budget is about three or four hundred million dollars a year now that sounds like a lot of money to you and me but actually if you think about it it's just over a dollar per American, which is wild because aging causes 85% of American deaths.

So I think what we really need to do is increase the amount of money that goes into the field. And these developments, they aren't decades and decades away. The fact is we've got a lot of these working in mice in the lab. We just need to do the human trials. We just need to try and make sure they're safe and effective in people. So I think this is going to happen in time for most people alive today. What do I mean by that? Well, the average person on planet Earth today

is somewhere under 40. And what that means is that if you live to an average life expectancy of, say, 80 in a rich country, then you've got 40 years of biological developments ahead of you. We've got AI. We've got loads of new tools arriving in biology and gene editing and stem cell therapy.

That's a huge amount of time for those developments to happen. And if we can do the science, if we can invest in that science, it could definitely arrive well before all of our 80th birthdays. So that's in plenty of time to make a difference to the trajectory of our ageing. So my call to action here is we've got to fund the science and then it can happen sooner for all of us, for our parents, for everyone we love and care about. LESLIE KENDRICK Andrew, you mentioned at the beginning of the podcast that people often raise ethical issues with you when you tell them what you do. What do you think are the key ethical issues that people could have if we produce a pill or some kind of treatment that slows

aging? I think the most common question I get is about population. It's about, you know, if people do live longer, aren't we going to end up cramming the earth full of humans? It's already pretty full of humans. We're already, you know, emitting too much carbon dioxide, too much plastic pollution, and isn't this only going to increase as the number of people does? Actually, the answer is it makes a surprisingly small difference, even if you completely remove age-related causes of death. It only makes, by my calculations, maybe a 10-15% difference to global population by 2050, and that assumes that we do that change today, and I'd happily work 10 or 15 percent harder you know to cut back my

carbon emissions to cut back my plastic use and so on if that meant that people were living much much longer healthier lives. Andrew people have been searching for the fountain of youth for centuries before we had social media and now we are inundated by I've've already mentioned it, wellness experts, people talking about longevity, lots of people promising that if you do certain things, you can reverse ageing. It's a really complicated landscape for people to navigate. What's your advice? Yeah, it really is. The first thing to say is there is nothing yet available to consumers

that can slow down the ageing process in any way that goes beyond the basic health advice. I think this can sound quite boring. This is why it doesn't necessarily get you millions and millions of views on social media, but the best advice that people can follow right now is eat well, get some exercise, get a good night's sleep, all of the basic stuff they know they should already be doing. This excites me a lot because if you understand the biology of aging, you can see that it's impacting on all those hallmarks we talked about, you can understand the connection between all of those things. And you also know that these drugs, these medicines are potentially coming quite soon. So if you can

extend your lifespan by doing that, you know, eating well, by getting enough sleep, by doing some exercise, you aren't just buying yourself health and quality of life today, you're also potentially buying scientists the time to do that work, which then means you can benefit from those drugs in future. I think the real challenge is that, you know, longevity has become a bit of a buzzword. I think the science does underpin that, but I think that it's sort of escaped beyond the lab. It's got got out of the lab and got a bit out of control in some ways. And you know, as we mentioned, there's this huge economic incentive, there's a huge market

to be got here. And so if you can come up with some quick fix, some supplements, some tests that can allow you to live that little bit longer, there's a huge, huge temptation for people to go for it. I think by the time these drugs are being offered by health services, you know, you can be pretty sure they've been thoroughly vetted because there are lots of hurdles things have to jump through. I think before that you've got to find some scientists, I think, to follow, people who

have actually got the scientific credentials rather than people who are just fitness influencers online. You can't tell how healthy someone is from their social media profile. And it might be that actually although they look very healthy externally, they might not be healthy internally. If they're posting all their biomarkers online, are you sure those biomarkers are really the tests they've done? Have they even actually done any of those tests? Or are they just using it to try and sell you a supplement or sell you a product? Think about, are these claims too good to be true? We're entering a difficult time because things that sound too good to

be true are shortly going to be true potentially. We are going to be able to slow down and reverse the aging process scientifically. But I think until that time comes, we've all just got to be very, very careful not to be drawn in by these big, big promises. I mean getting some exercise and eating well, these are all things we've been told for years by lots of people. A good night's sleep, tricky for you at the moment Andrew, or the newborn, I know. Absolutely, yeah. Yeah, we do know these things. Is there not one other thing that you're doing? Any other pill, any other supplement, anything else that you're taking to increase your longevity? I think the most interesting unconventional

piece of advice which comes from understanding the ageing biology is actually brushing your teeth. We've discovered there's this connection between the biology that's going on in your mouth and the biology in the rest of your body. So when you get tooth decay or when you get gum disease, those are bacteria in your mouth that are invading or trying to take control in there. That's a battle that your immune system can never win.

I already mentioned aging of the immune system is one of those hallmarks of aging. Actually, one of the ways in which it ages is it constantly gets a little bit paranoid. paranoid, sort of looking over its shoulder all the time. It's sort of this increasing chronic inflammation is what it's called. And because this is essentially what's going on in your mouth, because the immune system is fighting this battle against these bacteria that it can never quite win, we now know that inflammation in your mouth can drive inflammation in the rest of your body. So it can increase the

risk of heart disease, increase the risk of stroke, all of these heart related complications. There's even some evidence that it might be able to increase the risk of dementia if you have bad teeth and bad oral health generally. I think the evidence is compelling enough that it definitely gets me flossing, trying to clean between my teeth, brushing twice a day, all this sort of standard dental advice. But just realising that that has a connection to the ageing process has really redoubled my efforts to keep my teeth clean. Dr Andrew Steel, that is the best bit of advice anyone has given me for a long time. Thank you so much for joining us on The Global Story. You're very, very welcome. Thanks for having me.

And thanks so much to you for listening. If you want to get in touch, email us at theglobalstoryatbbc.com. You can send us a message or a voice note as well. Our WhatsApp is plus 44 330 123 9480. All of those details as well are in our show notes. Wherever you're listening in the world, this has been The Global Story. Thanks for having us in your headphones. Goodbye. If you enjoyed listening to The Global Story and would like to hear more, there's a new episode every weekday. Just search for the Global Story wherever you get your BBC podcasts and be sure to click subscribe or follow. We'll have another edition of the Global News

Podcast later. Until then, bye bye. Yoga is more than just exercise. It's the spiritual practice that millions swear by. And in 2017, Miranda, a university tutor from London, joins a yoga school that promises profound transformation. It felt a really safe and welcoming space. After the yoga classes, I felt amazing. But soon, that calm, welcoming atmosphere leads to something far darker, a journey that leads to allegations of grooming, trafficking, and exploitation across international borders.

I don't have my passport, I don't have my phone, I don't have my bank cards, I have nothing. The passport being taken, the being in a house and not feeling like they can leave. World of Secrets is where untold stories are unveiled and hidden realities are exposed. In this new series, we're confronting the dark side of the wellness industry, where the hope of a spiritual breakthrough gives way to disturbing accusations. You just get sucked in so gradually and it's done so skillfully that you don't realize. And it's like this the secret that's there. I wanted to believe that you know that whatever they were doing,

even if it seemed gross to me, was for some spiritual reason that I couldn't yet understand. Revealing the hidden secrets of a global yoga network. I feel that I have no other choice. The only thing I can do is to speak about this and to put my reputation and everything else on the line. I want truth and justice and for other people to not be hurt, for things to be different in the future.

To bring it into the light and almost alchemize some of that evil stuff that went on and take back the power. World of Secrets, season six, The Bad Guru. Listen wherever you get your podcasts.