ZOE Science & Nutrition - Professor Tim Spector: I was wrong about Vitamin D & sunlight! The 7 health habits he's changed his mind about

Episode Date: March 12, 2026

What health habits actually protect your brain and long-term health?  In this episode, Professor Tim Spector shares the seven health ideas he has changed his mind about after reviewing new research. From oral health and inflammation to vitamin D, sleep, and exercise, Tim explains the daily habits he now prioritises and helps us understand what we should do differently if the science changes. Tim revisits 7 common health beliefs and explains how new evidence has shifted his thinking. He explores the link between oral health, inflammation and brain ageing, and discusses vitamin D, sunlight and omega-3s. The conversation also looks at sleep timing, exercise and how everyday habits interact with our biology. Tim also shares the small changes he now makes in his own routine and provides practical ideas for incorporating them into your daily life. We all know that science evolves as new evidence emerges, so if the research changes, should our daily health habits change too? 🌱 Try our science-backed and tasty wholefood supplement Daily 30+ Get our brand-new app and Gut Health Test designed by world-leading gut health and nutrition scientists to build healthy eating habits 👉 Join ZOE Follow ZOE on Instagram. Timecodes 00:00 Intro 04:00 The nutrition advice scientists completely reversed 08:30 How scientists decide if a health trend is real 10:30 The vitamin D discovery that fooled scientists for years 12:35 The one health belief Tim is more convinced about than ever 14:00 The public health threat Tim says may be worse than smoking 15:20 The new research linking oral health to dementia 17:05 How mouth bacteria may affect your brain 18:20 The test that revealed plastic in Tim’s blood 20:15 The simple changes Tim made to reduce microplastics 21:40 The omega-3 test most doctors still don’t use 23:05 Why Tim chose food over omega-3 supplements 24:50 The omega-3 measurement scientists now care about most 26:40 Should vegans worry about omega-3? 29:25 The vitamin deficiency Tim has had since he was 18 31:20 The surprising brain benefits of folic acid 33:10 Why supplements should be personalised 34:30 Why Tim changed his mind about vitamin D 36:15 The simple way sunlight doubled his vitamin D 38:10 Why we shouldn’t fear winter sun 39:45 The exercise change Tim made this year 42:05 The muscle supplement Tim thought was “complete rubbish” 43:30 The sleep rule Tim now follows every night 45:30 The unusual sleep experiment Tim tried 📚Books by our ZOE Scientists The Food For Life Cookbook Every Body Should Know This by Dr Federica Amati Food For Life by Prof. Tim Spector Ferment by Prof. Tim Spector Good Mood Food (preorder) by Prof. Tim Spector Free resources from ZOE The Hormone Harmony Guide: Tuning Your Body’s Internal Orchestra Eating for Better Brain Health: Your brain-gut blueprint How to eat in 2026 - Discover ZOE’s 8 nutrition principles for long-term health Live Healthier: Top 10 Tips From ZOE Science & Nutrition Gut Guide - For a Healthier Microbiome in Weeks  Better Breakfast Guide Mentioned in today's episode What is your gut-brain connection and what role does nutrition play? Oral Health and Dementia, Journal of Dental Research (2025) Neuroinflammation: A Distal Consequence of Periodontitis, Journal of Dental Research (2022) Vitamin D Supplementation and the Incidence of Fractures, JGIM (2024) Does a good diet reduce your heart disease risk? Vitamin B12 and Age-Related Cognitive Decline-Dementia and "Alzheimer's Disease", FNB (2024) Vitamin D and Risk for Type 2 Diabetes, Annals of Internal Medicine (2023) Effects of Creatine Supplementation and Resistance Training, Nutrients (2024) Why you're probably breathing wrong (and what to do about it) | James Nestor Have feedback or a topic you'd like us to cover? Let us know here. Episode transcripts are available here.

Welcome to Zoe Science and Nutrition, where world-leading scientists explain how their research can improve your health. Health advice never stands still. One year we cut fat, the next we fear sugar. We demonise seed oils, and then we defend them. Their headlines move quickly, but inside the body, change unfolds slowly. Arteries clog over decades. Risk accumulates long before symptoms appear. Professor Tim Specter, one of the world's most cited scientist,

has spent years studying how food and lifestyle shape these invisible processes. He challenged calorie counting when everyone else believed in it. He warned about ultra-processed food, while many nutrition scientists deny that there was even such a thing. And of course he has led the world in understanding the central role of the microbiome in our health. But science does not freeze in time. New trials emerge, larger data sets appear. Evidence deepens, or sometimes it reverses.

This year, Tim has been examining his own health closely. He's reviewing new research. He's looking at his own test results. Today, Tim explains where he has changed his mind, where he hasn't, and how he decides when new evidence is strong enough to act on. He shares the seven new habits that he's started in 2026, from supplements and new exercises to sleep and oral health, and the reasoning behind each one. Because the challenge isn't keeping up with every new health claim on social media.

It's knowing which ones deserve your attention and which ones you can safely ignore. By the end of this episode, you won't just have heard the changes that one of the world's top scientists have made in his life. You'll understand how to navigate shifting advice for yourself. Tim, thank you for joining me today. Great to be here. I don't really need to tell you the drill. We have a set of Q&A questions. The good news is you don't know what they are, but I do.

Okay, far away. If I brush my teeth badly, could this impact my brain? brain health. Definitely. Have you changed the way that you exercise this year? I have a little bit, yes. Is folic acid only important for women? No, as I've recently discovered. Is it true that you now have rippling biceps thanks to your new workout routine? You can see for yourself, Jonathan. Yeah, I mean, you know, I've added at least 1% to my muscle mouse. All right. And then finally, what developing area of science are you most excited about in 2026? I'm really into the brain and the gut-brain connection. I just think it's absolutely fascinating.

And a lot of that has come out of the Zoe studies that have pointed in that direction, areas we didn't think about when we started Zoe. I'd like to start before we get into like the specific things that you've changed in the last year, maybe step back a little bit and say, what is it about nutrition science that means that we don't just know all the answers? Because I think I was generally brought up to believe, well, science like has figured all this stuff out. And I certainly was under the impression, you know, 40 years ago that the government knew exactly what we should eat.

there's a certain naivety about public perception of these things in a way because governments are forced to have guidelines and guidelines tend to be very black and white and there isn't really room for nuance when people are giving out a leaflet or something and so this then leads to a mentality that we have to follow the guidelines and that the guidelines must be correct otherwise all our foundations are going to crumble and that's why we've taken to taken so long to get to this point to realize that most of the guidelines were wrong and that actually the science has changed. And can you give an example of where, like, scientific opinion has changed in a big way in your lifetime? In the nutrition space, I was brought up to think

that fat was really bad for you. As a junior doctor was telling my patients, avoid fats, have starchy foods, things like rice, pasta, potatoes, they're the stuff to have. That's really good for you. And they were, of course, in the guidelines. Nobody really questioned them, just kept saying it, and no research was done to prove the opposite. And it took ages until this has been reversed. And now most countries, although this country is lagging behind in the UK, but even in the US, they've now switched the concept of fat being bad to saying, actually, many fats are good for you. So that's probably the classic one where we made a 180 degree switch just in a few years, although it seems to have taken much longer than it should have done.

And in that case, what I feel is from just talking to lots of scientists that this is a process of lots and lots of different scientists doing lots of different studies, reaching a point where there seemed to be quite a lot of scientific consensus about this for a long time, and then actually being very slow to change, like, government guidelines and therefore public opinion? Yes, exactly right. The evidence became overwhelming about 10 years ago. And I remember going to some early nutrition conferences. And for the first time hearing respected epidemiology colleagues who are generally the most conservative group of doctors saying, yes, we believe, you know, this fat idea is completely wrong. and the evidence is now overwhelming. And it's taken sort of 10 years from that point to starting to get changes in guidelines. It's incredibly slow because people feel that things like dietary guidelines have such

knock-on effects on the industry and changing formulation and changing commercial products that it's not something that should be rushed or just changed. And so this is why nutrition is different to other fields of science because it has this big, industry over it and they're lobbying to make sure that nothing happens fast. And so is this different if you were working in cancer or heart disease and your work was only going to doctors to change their advice rather than actually just going to everybody to change what they eat, would it be easier to sort of change the advice and make sure the advice was more up to date? Yes, in theory, but doctors just like many other professions

are also set in their ways and they don't like to change. Really? Yes, it's hard to believe, isn't it, Jonathan? We're a stubborn lot, and once you get into a nice way of doing something or treating people and if you believe it,

it's quite hard to change your mind on it. And the classic story was surgeons cutting the vagus nerve for ulcers. And it took 20 years to convince doctors to stop doing this so-called vagotomy operation because they enjoyed doing it. You know, surgeons loved this operation, although it turned out to be completely useless

and used antibiotics instead. So even in medicine, it can take a long time to shift patterns and behaviors, but nutrition is even worse than most of these branches. So I think that helps to understand why there's this delay between maybe the science and what we all sort of understand. I'd love to go more personal now.

How do you decide when a new scientific finding is worth incorporating into your actual lifestyle? That's a really hard question. I'm generally skeptical of any new finding that comes out of the blue. So if I see something, as we increasingly do on social media, some new trend coming out, the average influencer on social media isn't a scientist. They don't really know how to rank the different levels of evidence.

So I take various levels of evidence. I generally ignore stuff that's done in test tubes. Just on test tubes, we added this magic seamos to cancer cells and it killed them all. I ignore that. It's just a pure example. And it's seamoss to mice and it stopped them cancers growing. Slightly interesting, but nine times out of ten completely irrelevant for humans. And then some small study where they did a pilot study and they gave seamoss to people with cancer

and improve some of their outcomes, yeah, okay, we're starting to get interesting. Then you do a randomized study of seamos versus non-simoss and people with cancer, and you get a survival advantage. Now I'm interested. And I'm even more interested if you have a couple of studies and you put them together in a meta-analysis. So then once I've got this randomized control study, I'd say, okay, I'm going to look at taking seamos. Am I going to put seamos in my mooseley every morning? on my breakfast bowl.

So it's a journey, but it means you do have to have a bit of a scientific brain to think of it in those terms, because the average internet influence is just going to look at any of this data and see them all as the same. And yet one is a thousand times more powerful than the other. And I seem to remember you telling me in one of our podcasts that there were some big studies, I think, to do with breaking your bones, which really changed, for example, your mind about something

that you'd been quite convinced about, in science before, but I don't remember any of the details. Can you remind me? Yes, we were talking about vitamin D and how the early studies of vitamin D showed that it worked, that it had really important effects on bone, bone turnover, bone biomarkers, and everybody worried about osteoboros trying to prevent it should be on vitamin D medication. It was only when they started doing really big studies with good placebo groups, followed for a long time, they found that the fracture rates in the two groups were no different at all. Because they'd been using in the past A small numbers and like surrogate markers.

These are like chemicals that the bones produce to show that they're healthier or whatever, what we call intermediate biomarkers. But when it actually got to the big studies with fractures, actually there was no difference. People didn't believe the first negative study. They didn't believe the second one. but by the time they got to the third or the tenth, they did believe it. And that's now why osteoporosis experts know that vitamin D is not useful for the vast majority of people in preventing fractures. I was fooled by vitamin D and I was a big promoter of vitamin D back in the day for osteoporosis.

And it's still being used because most doctors haven't changed their practice. And so does a good scientist change his mind? A good scientist should change their mind because they should be always looking for a reason to contradict their current theory. You know, what evidence is there that's going to make what I think not true? I think that's really interesting. One of the thing I'm struck is certainly whenever you have two scientists in a room and sometimes we have like 10 scientists in a room, they all argue with each other all the time. But the other thing I really do notice is that skepticism is also something they bring to their own work and that sometimes proving that something is wrong is. as exciting as not. Absolutely. I think scientists generally will be humble because they realize, you know, we're on a learning curve and that all scientists have made mistakes in their lives,

as have all doctors. And it's realizing that and not just carrying on regardless, because I've said it five years ago and I keep shouting, it's got to be true. I would like to talk now about the things that you're changing. But maybe actually let's start with what you haven't changed in 26. So I know you've looked at all. of this again and thought quite hard. But I'd like to start actually with what are the principles that you still have a lot of conviction about? Well, I'm still very convinced more than ever that the gut microbiome is crucial for our overall health. And if we have a healthy gut microbiome, pretty much everything else follows. And the evidence that we've been seeing continually just

keeps to enhance that view. And was there anything important in terms of the science last year that sort of reinforce that view for you? Things like food quality are increasingly getting noticed as causes of our mental health and our physical health. That wasn't the case five years ago. And if you're talking about food quality, obviously which organ does that impact more than anything? It's the gut microbes.

There's also been a lot of really interesting immunology work that got a real boost after COVID. Basically, I'm understanding how the immune system is interacting with the gut microbes is revealing just how important it is to our biology. So, you know, it's across all sectors that we're learning this, plus our own Zoe studies that just keep showing that when you can improve people's gut microbes, you can improve so many aspects of our health, both short term and long term, and in the brain and in the gut. And you haven't mentioned so far ultra-processed foods? I haven't changed my mind on ultra-processed foods at all, and I think the evidence is getting clearer that they're the most important public health danger out there for the population.

So I think they've overtaken smoking as the number one enemy we should be dealing with. The evidence is building, but we haven't had good definitions of it up to this point, and we've had too broad a description of what ultra-processed foods. So I'm really happy to be helping with the Zoe redefinition of ultra-processed foods in these medium, high and low categories of risk. But that is showing us how important understanding the food is. Around the world, this momentum is gathering a pace. And I think the next phase is to really define better what the harmful foods are

and not lump it altogether. We'll get much better results. So I'm pleased to hear that in the last year, you haven't abandoned your belief in the gut health revolution because I think I'd be out of a job. So that's good. I'd like now to talk about the things where you have changed your mind, and you get me a list of seven things. And the first thing that you said is that you've changed your mind about oral health.

So can you tell me what's so important about having clean teeth? Another notification. Something else to add to the to-do list? Is it work? Is it life admin? Or maybe another email from your boss? your heart rate might be quickening at the thought. After all, life is full of little moments that add to our mental load. If you're feeling wired, tired, irritable or on edge, that's your

hormones responding to everyday stresses. They're trying to tell you something, and your diet could be part of the solution. Your gut is a hormone factory, producing and responding to all the hormones that affect your hunger, mood, energy levels and stress responses. Feeding at the right foods is a crucial step to supporting those systems. That's why gut health experts, Zoe, and reproductive health pioneers, hertility, have teamed up to create a free guide, grounded in science, to help you decode what your hormones are trying to tell you.

You'll find out how stress responses can impact your body and how diet influences hormones, metabolism, and mood. You'll also find delicious recipes that support these systems. Learn more about your hormones today, and download the free guide at zoe.com forward slash hertility or click the link in the episode description. I always knew that clean your teeth was important, stop falling apart and getting gum disease and your teeth falling out. And there was always a story about if you didn't brush them properly, you'd get more heart attacks because there was certain microbes, something called strep mutants that also had this potential effect on your heart.

But the last year or so, I've been diving into this more, and there's actually some good studies showing that your risk of dementia can be reduced by something like 20 to 40% just by cleaning your teeth optimally, not just cleaning your teeth optimally, and discovered this means flossing or using a pick. There was only when I started doing this and I started seeing, I was getting bleeding. There were a few areas right at the back, really hard to reach. used to bleed when I just do them, I didn't think much of it. And it realized, well, you just got to keep going until you don't get bleeding. That means that you don't have inflammation. That means

you're doing something really positive for your health in reducing your risk of future early dementia and heart disease. Can you explain how flossing every day can have an effect on something that's not in my mouth, but it's in my heart or in my brain? Yes, it all comes back to our friends microbes, microbiome. Just as in our gut and our colon, we've got these microbes in our mouth, in our saliva. They're there all the time, and they have their own community. And essentially, what you're doing, if you've got bits of food that are stuck in your gums and very hard to reach places, this feeds these bad bacteria in your mouth. And they are pro-inflammatory. so they often send out the signals to our immune system to say things aren't great.

So they're just heightening the level of stress in the same way as if you're eating lots of junk food in your gut. Those signals will go to the immune system. And we now know, again, only very recently that the immune system communicates with the brain. We have immune cells in our brain recently discovered. And this seems to be a mechanism that your brain thinks it's under stress, because it's getting these signals. It thinks it's like fighting infections all the time. And that seems to prematurely age it.

So, yeah, it's really cool to realize how much of your body is connected, things that we had no idea about before. It seemed crazy if you went to someone 10 years ago to say this. And are you now flossing once a day, twice a day, 10 times a day? I will do it once a day unless I've got a problem, in which case I'll do it twice a day. And I use these special picks now. Brilliant. Let me go on to the second one. So I understand that you did a scan in your body for

microplastics. Is that right? I had this state-of-the-art dementia screening test, including all kinds of blood tests, scans that would be used for me to take action to delay or prevent dementia because I have a higher risk of dementia because of my mother having vascular dementia. And as part of this extensive all-day testing, I had this blood test done in the Netherlands for microplastics. And it showed I had above-average levels. And this was a shock to me. I thought, why is that? And it turns out that some of them were in my particles that probably came from my lungs

and others through the food you're eating. So you can get them from all kinds of places. You are saying that there were tiny little bits of plastic floating. around in your blood. And so they just literally took like a blood test like normal. And here they're actually measuring plastic in it. And they found a lot. That's correct, yes.

Essentially, it's like a plastic assay in your blood. And just the fact they're able to record any is slightly worried. I think you'd agree. Yes, detecta will be bad enough. And then you say, well, actually, you're above average. That was even worse. So I did start researching that and thinking, well, yes, it is associated with people who have dementia, end up, you look in their brains,

you can see some microplastics, it's associated with various cancers, all associated. There isn't hard evidence as such, as we've been describing, but it's become added to that list of things that you want to avoid, like pesticides or antibiotics or all these things that we'd rather do without. It just adds to this stress of life. Another thing I've got to worry about. So I said, what could I do easily to do this? And so they said, well, move out of London was one, which isn't quite so easy to do. But I could spend more time on the beach, I think, and in Spain, Jonathan, I'll show you to prove of that. The other was maybe reduce plastic packaging in your food.

I don't have very much anyway because I don't have things like ready meals. But it made me, you know, always be more determined to use my Zoe metal water bottle rather than a plastic one and try not to use glass rather than plastic. And I even changed my toothpaste. I realized that most of the toothpaste we use have not only lots of additives, but a lot of them have microplastics in them, as do a lot of shampoos. So going to more natural ones, and I use a natural toothpaste now that's made with fennel, for example. So, yeah, I'm keeping my eye on it.

I know the science isn't perfect, but if there's some easy things, then I'm happy to do that. I feel like this is very new and I'm sort of trying to ignore it because I don't want another thing to worry about. No, for the anxious, I wouldn't do it, you know, but I'm trying to do these experience for other people in a way. So I take the stress. Thank you for doing that, Tim. Well, let's move on to the third one, omega-3. And I know that's a topic that's hotly debated in nutrition circles in terms of like the value of taking that as a supplement rather than just something that's within a food. What did your tests tell you about that? And what have you taken away?

So my tests showed me that I had relatively low levels of omega-3 in my blood, and also slightly high levels of omega-6, which is another fatty acid. And there used to be this idea that the ratio of the two was really important. You should cut out omega-6s. That turns out to be rubbish. We've reversed our view on that in the last five years. but omega-3 still remains important. But absolute levels aren't that interesting, according to the latest studies.

But what is interesting is something called the omega-3 index, where you look at the amount of the important omega-3 is in your blood cells. And there's something called EPA and DPA, which are the subtypes. And I was pretty low on those. So I was advised in this clinic to go on supplements. They said, go and take an expensive supplement. This is what you do. I said, I'm not very keen on that, although the studies have shown that people with low levels,

you know, do benefit from supplements in terms of heart disease. People average levels don't, but people with low levels do. I said, I'm going to try and eat more oily fish. And so, for the last year, I've been making sure that every week I'm getting some anchovies and some sardines and some salmon. in my diet, particularly easy when I spend time in Spain, eating lots of anchovies, and I do love them. And I retested myself and my levels are now above average without having to take an omega-3 supplement. And that's because the fish itself contains those healthy omega-3s you were talking about?

They do, that's right, because they eat little planktones and things that do produce these plant products. So, yes, they're very good source. And I think it just shows you that you don't have to always reach for a supplement when the food could actually be a better supplement because not only you're getting the goodness from those particular fatty acids that we know about, but there's lots of other stuff that we don't yet know about that can be really beneficial. And they're really tasting. And that's why in my new cookbook, a little plug here, Jonathan, I've got lots of anchovy and sardine recipes in there. I said because I realize that plants are great, but every now and again, we need to spice them up. And just to clarify, for anyone listening, this is a new cook, but you haven't actually released yet. So if anyone's feeling, why I don't know, know about that, actually, you're working on it.

It doesn't exist. I've been working on it and working on recipes. And I'm always trying to work out ways to put things like, you know, macro, sardines and anchovies into those recipes because we need to eat more of them. So you mentioned something about omega-3 index, that that was the thing that was low that triggered your concern. Is that like a standard test that I get if I get like a standard blood test? How would someone listening who wants to know about this for themselves solve that? It's fairly standard in the United States. It's not standard in the UK.

So most GPs wouldn't be able to easily get people to test it. And I think it just shows a slight mismatch between the latest nutritional science and what the NHS, for example, is able to offer. And is the omega-3 index something different than just your omega-3 levels? I'm sorry, I'm still struggling to follow that. Yes. So in the past, people have looked at the ratio of omega-3 to omega-6. And the old idea was omega-3 was good, omega-6 was bad, and therefore you wanted a high ratio.

We now know that you want both to be high, omega-6 and omega-3. So that whole ratio idea has really gone out the window. And this new test really just looks at the amount of blood cells in your body that have sufficient levels of these really key omega-3s. Because omega-3 is a family. There's quite a lot of them. So we're just focusing on the two important ones. That's really what we should be looking at. So this is now the gold standard in clinical research.

And it's going to take a while to come to some bits of the more conservative. of medical world. What would you say to anyone listening who's a vegan or really hates fish who is thinking, oh, I think I'd like to be able to increase my level of these healthy omega-3s? If they're already on a pretty healthy vegan diet and they're taking all the nuts and seeds and other sources of all the plants that contain these as well, I would say, yeah, get tested and in those case, if you're low, take a supplement. But randomly, some people will have naturally high levels, some people have low levels. It's not like everybody needs it.

I think the evidence now is if you are low, it's probably worth taking their supplements. But a lot of people like me can get by just by upping their real food intake. And is your belief that if I'm thinking about this and saying, well, one, I just pop an omega-3 tablet, right? People are always trying to sell me that. Is that just as good as the oily fish that you're talking about? We don't know is the honest answer. But generally my belief is that if there's a food alternative, it tends to be better because it's got all kinds of other benefits to go with it that we haven't yet been able to uncover.

Let's move on to number four. And we're still on nutrients and supplements because we're now going on to vitamin B12, about which I know absolutely nothing. So what is it and where does it come from? Well, it's one of the essential B vitamins. And although our body does produce some of it, our microbes produce some of it, we end up eliminating it. We can't absorb it. It's a bit of a design fault in humans.

It's produced too low in the body, so it comes out in the toilet rather than back into our bloodstream. So we rely on food sources for it. And a lot of it is in meat and dairy products, contain a lot of this B12. So if you are a vegan, for example, you're going to be borderline low or deficient in B12 and SU are either lucky or take supplements. So it's well known that if you don't, you do get problems of your nerves, you can get fatigiant. muscle problems and it also affects your blood cells. So definitely worth taking B12 supplements if you're at risk or you have low levels. It turns out since I was 18 I've had low levels of B12. I never really knew why and also low levels of folic acid which is a related B vitamin as well. The two sort of tend

to go together. I've always struggled to keep these levels up. Obviously I was completely vegetarian for six years or so. I now do eat some meat, but really hard to get those levels up. I took oral medication. That didn't really work. And it turns out that having a low B12 and a folate is also bad for your blood pressure and increases other markers that seem, in ways we don't understand, mess up with the blood vessels. So I now take this really seriously. And as well as B12 supplements, I also take folic acid supplements for the first time. And there were some studies that have come out when I was researching my new book that show folic acid is really good for your brain.

And that we'd known for ages that for pregnant women or women think of conceiving, folic acid supplementation was crucial for reducing brain and nerve defects in babies. and it had a dramatic benefit. Now we know that it has a role in helping cognition in older adults. So there are several long-term trials show that folic acid supplementation is good for adult brains. So I've got another reason to make sure my folic acid levels are high. I check my bloods just last week and now I've gone from really low levels to really high levels of folic acid as well. So I've changed my mind completely on that.

I would have said folic acid, that's a waste of time, minimum B12, that's all that matters. And so you are now taking a daily supplement for the B12 and folic acid that you weren't doing a year ago? Yes, that's right. And if someone's listening to this, should they be thinking, oh, well, I guess I should just be taking a supplement for B12 and folic acid every day? Most people have high folate levels. As long as you eat leafy greens, you're getting a lot. So you can have like four-fold differences in folate levels. And there's some evidence if you overdo the folate, you can have problems.

Some studies showing you can have so-called epigenetic changes. You can switch your genes on and off with too much folate. So I definitely don't think everybody should be doing this. But get a blood test, get checked out, and see if you really need this stuff. Okay, so you're not saying to everybody this is their top concern they should have, but you're talking about the way in which this stuff is personal, you had these results and this is highly personalized. And this is a case where you have, in fact, said like these supplements make sense for me.

They make sense to me with my funny genes, yes. Let's move on to the next one. Vitamin D, which I know is also a very controversial topic, and you touched on that a little bit already. What is it? Why has it been so controversial? And what did your test show? My tests showed I had levels about 45 millimoles per litre, which is about what they call borderline insufficiency in most labs in the UK and the US.

They said, oh, you should go on vitamin D replacements. I said, well, you're measuring me in winter. I'm dead against vitamin D tablets. I think 45 is probably fine and it'll probably go up in summer. I didn't take any vitamin D tablets, but I did recheck my vitamin D having just come back from Australia and my vitamin D has gone up, you know, has doubled just from a bit of winter sunshine. So it shows how flexible we are. We shouldn't rely on one test.

But I am interested that I've been for the last 20 years saying that everything about vitamin D is a sham, but there are some studies that have convinced me that's not. completely true. It's been promoted for 100 different diseases, and I would say in 98 of them, it's complete rubbish. It's probably useful if you've got a risk of multiple sclerosis. It reduces by a few hours if you take it during a viral infection. But the latest study shows that it can reduce your risk of getting type 2 diabetes. So it's a really interesting compound, which we still don't understand. And it turns out that it's proving to be useful for the very stuff we had no idea it would be useful. And the stuff we thought it would be good for, it has absolutely no effect

and may actually be harmful. So I'm keeping a close eye on it now. And I'm actually interested to see what my vitamin D level is. But if I can keep it high by going to nice destinations and getting a suntan, that's definitely my preference because I think that probably our natural way of getting vitamin D is going to be healthier than a tablet. Now, Tim, I called you up. after a health check about a month ago, actually. I had this blood tests, and one of the things that it said was that my vitamin D levels were low. And my doctor said, oh, your vitamin D levels are low. He actually said everything else is good.

I think you should take a supplement. Can you remember what you told me? Yeah, I said it's borderline. I said 20 years ago we would call that completely normal. We've shifted our levels of what we call normal over the last 20 years without actually much justification. And so I said, I wouldn't worry about it. I think you hadn't been in the sun for a while. It will probably go up, have some more vitamin D foods, have some nice mushrooms.

Don't worry about it too much. Maybe get a retest. I wouldn't bother going on vitamin D tablets at that level. Most of the studies show no real difference at that borderline level. And other than being in the sun, which if you live somewhere in very normal, the lee, can be hard in the winter. Is there anything else that you can do to increase your vitamin D other than to take a vitamin D tablet? Oily fish. So the ones we've talked about, the anchovies, salmon, the mackerel, herring. There's quite a lot in mushrooms. Mushrooms can produce vitamin D

as well themselves, interestingly. So you can put your mushrooms to sunbathe in the windowsill for a couple of days. That will also help them. Yeah, and realize that you can actually get your levels up quite a lot in summer, and that we've evolved really to have fluctuating vitamin D levels. So you'll survive a few months with slightly low levels. On this one is interesting. So my wife's a dermatologist, and she was definitely brought up with this view that you should never have like any son whatsoever because of the risk of skin cancer. And I think that has sort of been the teaching not only to dermatologists, but I feel like

the public health that we've been taught. And she has said to me fairly recently that this is something. where she's changed her mind in the last few years because of the vitamin D impact. So she's still absolutely virulent that you mustn't get sunburn. But actually, I've amazingly, you know, she will actually go out in the winter in the sun without something that is blocking the sunshine. And is that also part of the advice to not be maybe as scared of the sun as I think many of us have been told to be?

Absolutely. Yes, winter is a time when we should be getting as much sun as we can. That will help get a lot of these important chemicals from the sun. There might be other advantages as well we don't know of yet we can't measure. But yeah, we shouldn't be protecting ourselves in winter. There's no evidence that that's really useful for stopping wrinkling, for example. That's just a myth. So again, it's going back to more natural processes.

Protect yourselves against sunburn. the rest of the time try and get us lots of daylight and sunlight on your skin. It's not often that you hear one of the world's top scientists explain exactly what he's changed in his daily routine and why based on the very latest science. This episode cuts through the noise with clear guidance on which habits really protect your long-term health, which ones you don't really need. Why not share it with someone else who's trying to get their health just right this year? Let me move on to number six.

and your next change concerns exercise, which I guess we touched in the Q&A at the beginning. I'm hoping you're going to tell me that I don't need to go to the gym anymore and can just sit on the sofa. Sadly not. Exercise won't go away. It keeps coming up as an important factor, both in our mental health and our physical health. People disagree at how much you have to do. The sort of idea that you just have to do three, 20 minute bursts in a week seems to be going out the window. There isn't a threshold.

There's a continuum and above which, yeah, with a threshold at the top, probably, you know, doing more than two hours a day is not really useful. And you can certainly over exercise. So there's some evidence that professional athletes are doing a little bit of harm to their bodies. So we've got to find the sweet spot. And the latest evidence suggests that we should be doing much more of a mixture of exercises. So I went and discussed this in this clinic and I said, well, I do quite a lot of cycling, a lot of swimming. My cardio is quite good.

And I'm into yoga, whatever. And they said, oh, how much weight training are you doing? So, well, not very much. And so that is now an important part of preventing aging, is adding this variety of exercises into our lives. So now I mix up doing some stuff with lightweights as well as Pilates and just thinking that I'm trying to in a week get a more variety of exercise rather than just doing the same stuff on a fixed bike or a peloton or whatever it is.

And so Tim, what specifically are you doing now that you weren't doing a year ago? I bought a set of weights and I will try at least two or three times a week to have 20 to 30 minutes where I'm using these weights. So that I'm trying to build up my lean mass more than I was there before rather than just focusing on my heart and my lungs. I'm hoping this is going to pay dividends. But I think the important thing is I'm trying to find things that I enjoy. when you're given us a spreadsheet from some physio or whatever, it seems incredibly dull. You do it once or twice, then you just give up.

So you've got to find ways that make it interesting. And, you know, so I will go to a Pilates class where there's live things going on or you find a nice YouTube video. So it's about finding what you enjoy doing and realizing, again, a bit like for your gut, I think diversity of exercise, is actually more important than anything else.

And Pilates is a sort of weight training? Yes. Focuses a lot on your core, but it is increasing a lot of the muscles of the core that maybe you won't get just by humping a few weights around. So again, it's, you know, yoga Pilates, a bit of a bit of lightweights, doing some cycling, some swimming.

If you do all that, you're pretty much covering all your bases. And there's a lot of evidence that as people get older, They need to do more of the weight training and less of the cardio. Yeah, walking more places, you know, as you get older, I think you just realize that, you know, your fitness is important. What about creatine, which I understand is very popular with people who are building muscles? What are your thoughts on that? I thought it was complete rubbish. Then I started looking at the most recent studies.

And it definitely does work. If you combine it with exercise, you will increase. your muscle mass. The problem is, Jonathan, it's only by 1.7%. 1.7%. And so I took it for a few weeks. I looked at my arms.

I can't tell any difference here. It's horrible. It makes me feel a bit sick to take it. I'm going to stop it. It's not worth it. So until they show that creatine really has a definite benefit on cognition,

which is suggested it might do, I'm not going to bother. Right. Let's come to the seventh and final one, which is sleep, which is one of my favorite pastimes, although I always feel I don't in fact get enough of it. I thought everyone agreed it was good for you. So what's changed? We're now measuring it more than we used to in our previous studies. People didn't bother. They said, do you sleep well, yes or no. Now we're actually got wearables, people

are looking at sleep quality, sleep duration, have much better scientific data. And it all suggests that it's in the top three of things we need to get right, as well as exercise and as well as diet, sleep is important. A poor night's sleep is equivalent to working, you know, having had two double gin and tonics. You really, a brain isn't working well. So it's also important in age-related research, really important. So I've made a conscious effort this year to try and improve my sleep quality and duration. I go to bed half an hour earlier. I try not to eat or drink. within two hours of going to bed. And Tim, why do you stop the eating and drinking within two hours of bed?

There's some evidence that that reduces your sleep quality. If your body's too busy still digesting your meal, the whole body is not in sleep mode. And so you may not get as deep and relaxing sleep. And it may stop you sleeping as profoundly as before. So I think your activities before bedtime are as important as the actual environment you are asleep at. So you shouldn't exercise just before bed or eat or drink anything that's going to mean your body's got to deal with that while you're trying to put you into this relaxed state of mind.

This is yet another black mark against my dark chocolate on the sofa at 11 p.m. just before I go to bed. Yes. I mean, it depends how much, but hopefully if it's not too much, your body won't be too stressed. But if you can have it an hour earlier, it would definitely be better. better. So I think that all comes back also not only to the sleep business, but about resting your gut. But they are all related. And, you know, giving your gut a rest is putting it into sleep. It's got a circadian rhythm just like you do. So the more I keep talking about the gut health and it's circadian rhythm and how you give it a break, I'm suddenly thinking, well, maybe I need to give me a break as well. And that's about making sure that as I'm giving my gut a rest,

I'm giving my brain a rest, which means going to bed half an hour earlier, not being a rush to go to sleep. And giving yourself more time to sleep, I've also got a few gadgets that I've sort of invested in. Blackout curtains now in the room. And I've got earplugs that pay sounds of the sea that are soft. So I can't hear my poor wife snoring or the someone's car alarm going off. And I also experimented with mouth taping.

Really? I thought, I wasn't expecting to hear you tell me that. No, but, you know, I read the book Breath and did look it up. And the latest science isn't as convincing as I'd read in the book. A lot of trials show that it doesn't work very well in some people, but it seems to be highly personalized. And I said, I'll try it, because I was always waking up in the night with a dry mouth and I trigger me if to get someone to drink, then I'd go to the loo, and so it was

quite disruptive. And I found that since wearing it, I'm not thirsty at all, and my sleep quality is much better. So I'm going to keep doing it, but I realize it's not for everybody. That's really interesting. We did a podcast very recently with James Nester, and he was talking about this and has, I have committed to go and give this a go, but I haven't actually started yet. So now that is the second person telling me that I should try it. And your message is it's personal. So some people it will really work for, but the evidence is not clear that it works for everybody.

Definitely, yes. And it can actually be harmful to some people. So there's a real spectrum of how it behaves. And I think we're all quite different in terms of our noses and our breathing and our habits. So yeah. But I think everyone should give it a little try because it could make a dramatic difference to some people, but don't persist if you don't feel well on it. or, you know, and if you're very ill, definitely get some advice before you do.

Well, Tim, that's fascinating. And I think if I look across all of that, you know, it's a lot of little things that you've been tweaking, a number of things where you've clearly changed your mind. And somewhere it seems like you've, you know, sometimes like on vitamin D, you've almost gone in one direction, another, then back a little bit. And I think this is a great example of how you're saying, like the science changes. We get more data. and if you're going to be a good scientist, then you adjust your view of it.

Absolutely, yes. So I think it's a lesson for everyone is, you know, you may have fixed views on things. You may have heard fixed views on it, but nothing is absolute. And so keep an open mind. Let me try and run through the final seven things. I started with oral health. And I think this amazing fact that if your oral health is bad, you will have more heart attacks due to bugs in your mouth, and your risk of dementia can actually be reduced by 20 to 40%

if you're cleaning optimally. And so Tim, you've started using, like, by flossing using one of these picks every day in order to try and make sure that you reduce your risk of dementia. Absolutely. Second one is omega-3, where you tested yourself with this new test, is omega-3 index, which you said is quite common in the States. It's not standard today in the UK, but I imagine that will change, and which is measuring how much omega-3s you actually have in your blood cells, your levels were low.

And as a result, you said, like, I don't want to take supplements. I'm convinced that whole food will have a lot more overall benefit. You've added, I think you said specifically, anchovies, sardines, and salmon, and you got the level right back up again. Microplastics. You did this test. You got this rather distressing news that there's lots of microplastics in your blood. And I think what you said is it's unclear how harmful that is, but it doesn't say.

sound very good. And so you haven't completely re-engineered your life, but you have, for example, ditch the plastic water bottle using a metal water bottle. So just thinking about simple changes that might be reducing the amount of plastic. I've got a good water filter as well. I forgot to say that. So that's an easy thing you can do. And I think probably important for other chemicals you want to avoid. Brilliant. Then moving on to number four, B-12 and folic acid, which you said came together and that the interesting thing was, firstly, you've discovered you have this particular genetic variant, which is quite rare, which means that your levels are low, and that you care about this because there's this new science that says folic acid is not just about women who are

looking to conceive and are pregnant. We now know that matters for older adults as well. So basically, if your folic acid levels are low, you would suggest making sure you take a supplement in addition, obviously, to women who are thinking that they might get pregnant. Yeah, and as long as you're already taking lots of plants, yeah. It's in addition to plants, not instead of. Vitamin D, the science keeps moving around. You remain more relaxed about the vitamin D levels than the standard feedback that you might get from a test, particularly if it's in the winter because you feel this varies,

but you are taking action in the winter to try and make sure that you keep that vitamin D levels higher. And so that means, again, back to the oily fish. So you're getting two for one out of that. Mushrooms, you said, are high in vitamin D. And then critically, like, you do want to get sun exposure in the winter for the sun to make the vitamin D. Correct. Number six, exercise. You've always done exercise, but it's been a lot of cardio, like cycling and things like this.

And the evidence you feel now is it's really important to be mixing the exercise. And so for you, that means you needed to put in more weight training, which you've never really particularly liked. I know this because you've teased me about it in the past. But now you decide, like, I do need to add some of this as part of, like, wanting to reduce my risks of dementia. But it doesn't mean that it's only, like, going to the gym and lifting very heavy weights. You're talking about, like, Pilates as being part of that, that actually even, like, moderate

level of weights into your mixture. And again, it's a mix. It's not just doing one thing. And then you said you tried creatine for a bit. Then you looked deeper into the results you saw we gave you 1.7% improvement. Yeah, on average. And so you looked at your biceps after a few weeks and you decided that you couldn't see any benefit. It tasted horrible.

So you've junked it. But you're continuing to look at the data in terms of health benefits, which you don't think are clear yet. But you might reevaluate that. Yeah, for the brain. There's some early evidence that it could delay dementia, which would be really cool. but I'm not yet convinced. And finally on sleep, it's not new to know that sleep is really important for your health, but it sounds like you've got more serious about it.

Things like trying to stop eating and drinking within two hours of bed in order to sleep better, much stricter. Matt Walker will be very happy with all the things that you're doing about your bedroom as a cave. But interestingly, you've actually taken the more radical move of trying this mouth-tapping. and what you're saying, the evidence suggests that for some people, it could be harmful, for some people beneficial. In your case, you're feeling that it works really well.

Yeah, so far. Tim, thank you so much for coming in and almost experimenting on yourself and sharing the results with the rest of us. A pleasure. I'll end this episode with something I think you'll like, a free Zoe gut health guide. If you're a regular listener,

you know just how important it is to take care of your gut, Your gut microbiome is the gateway to better health, better sleep, energy and mood. The list just goes on. But many of us aren't sure how to best support our gut. I wasn't sure before doing Zoe, which is why we've developed an easy-to-follow gut health guide. It's completely free and offers five simple steps to improve your gut health. You'll get tips from Professor Tim Specter, Zoe's scientific co-founder and one of the world's most cited scientists, plus recipes and shopping lists straight to your inbox.

We'll also send you ongoing gut health and nutrition insights, including how Zoe can help. To get your free Zoe gut health guide, head on over to zoey.com slash gut guide. Thanks for tuning in and see you next time.