Daily habit to lower blood pressure, improve heart health and reduce dementia risk with Prof. Tim Spector

What if your blood pressure — even just a little too high — is quietly damaging your brain? What if it’s increasing your risk of a heart attack or stroke, without you ever feeling a thing?

In this episode, Prof. Tim Spector reveals why blood pressure is one of the most overlooked – and most dangerous – health issues today. He explains why “normal for your age” might not be safe at all, why medication alone isn’t the full answer, and how small, daily changes could dramatically reduce your risk of serious disease.

Can your gut microbes raise your blood pressure? Can a banana be as powerful as a pill? Is beetroot juice really three times more effective than cutting salt?

You’ll also learn why 80% of the salt we eat isn’t from the shaker, how stress and sleep secretly push your pressure up, and what most doctors still miss when treating hypertension. If you’ve ever been told your blood pressure’s “fine” — or never measured it at all — this episode might change the way you think about your future health.

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Transcript

Jonathan Wolf: Tim, thank you for joining me today. 

Prof. Tim Spector: A pleasure as always, Jonathan. 

Jonathan Wolf: So we're going to jump straight into the quickfire questions from our listeners. Is having high blood pressure dangerous? 

Prof. Tim Spector: Absolutely. 

Jonathan Wolf: Can high blood pressure increase your risk of dementia? 

Prof. Tim Spector: It can. 

Jonathan Wolf: Does reducing salt lower your blood pressure?

Prof. Tim Spector: Yes. 

Jonathan Wolf: Can you lower high blood pressure through mindfulness? 

Prof. Tim Spector: You can. 

Jonathan Wolf: Is it true that drinking beetroot juice can help with high blood pressure? 

Prof. Tim Spector: Yes. 

Jonathan Wolf: I don’t think I’ve ever managed to get that many yeses from you, Tim. Lastly, what's the most misunderstood thing about high blood pressure? 

Prof. Tim Spector: That you can feel it. That you know if your blood pressure's high, and people will say, oh, I'm angry, therefore my blood pressure's going up, I know how I'm feeling.

But you can't. It's a silent killer, and everyone needs to know what their blood pressure is, and that can dramatically lengthen their lives. 

Jonathan Wolf: Amazing. So, the team actually did some research for us before the show, and I had no idea how common it was to have high blood pressure.

So apparently, around half of adults in the U.S. have the condition, and about a third in the U.K. I have two close family members with high blood pressure, and in both cases, that's something that started as they entered their sixties. It wasn't something that the doctors said to them before, but it sort of started about then.

I also have to admit I have absolutely no idea what high blood pressure actually is, so what is it? 

Prof. Tim Spector: It is basically a hardening of the arteries and a thickening of the arteries so that they're not as flexible. These are the arteries, the blood vessels that go all around your body from your heart, pumping blood to every bit of your body, including your brain.

Each time your heart beats, there's a change in how much pressure is put into the system, and essentially, it's there to absorb that shock. So it's also there to have a system, so if you're exercising or you need to run away quickly, your blood pressure can go up in short bursts. And that's normal, and it comes back again quickly. 

So you want a flexible mobile system, and what happens when you have high blood pressure, which is also known as hypertension, is that it stays up. It doesn't just come up and go down. Your resting level is higher, so you've got more resistance to the whole system.

It's like your pipes are furring up a bit. They're just not as flexible and bendy, and this puts a strain on the rest of your body. So it has to work harder to do things. 

That's a very simple way of thinking about it. And as you said, it's incredibly common. And where we draw the line about it being normal, abnormal is a bit flexible itself.

So it could be that if we wanted to have the perfect blood pressure of, say, you know, indigenous tribes in Africa, then we would put our thresholds even lower, and maybe two-thirds of us would be counted as having high blood pressure in the West.

It's considered a metabolic problem as well. So metabolic syndrome, which I think we've talked about in the past, is a combination of clusters of things that we get in the West where you might get type two diabetes, you might get obesity, you get high cholesterol, and a part of that, as well as heart disease, is high blood pressure.

They seem to have similar causes and relationships, and they all lead on to one to the other. So if you've got one, you're more likely to get the others. So your whole body is put under stress, and that throws out all kinds of mechanisms. 

Now I've got high blood pressure. I got this rather suddenly overnight in about 2011. Most people get it slowly. It comes on slowly. Have you ever measured your blood pressure, Jonathan? 

Jonathan Wolf: I've had doctors measure my blood pressure, but I have never measured it myself. 

Prof. Tim Spector: Well, now's a chance to do it yourself. So I've got a blood pressure monitor for home use in front of you. Do you just want to slip it on now?

Jonathan Wolf: Absolutely. 

Prof. Tim Spector: On your left arm, roll your sleeve up. 

Jonathan Wolf: Roll my sleeve up. Just like the collar that you wear when you are seeing the doctor. 

Prof. Tim Spector: Yeah. There's no need now to have to go to your doctor to get your blood pressure measured. This is a device that everybody should have in their home because it's probably the single cheapest device that can save the most lives. 

So if you're on now, you're lined up, you can press the button that says start. And you just wait for it to slowly inflate. The idea is that you should be resting for a couple of minutes in a nice, stress-free scenario, just chatting.  

Jonathan Wolf: So, a live podcast is the definition of a stress-free...

Prof. Tim Spector: It is. Just chatting to me is so relaxing, isn't it, Jonathan? 

 And so you normally take three readings. Throw away the first one because you're stressed, and then you record the second and third ones, and it's something you should probably do once a week at home, to check that you are staying within a normal limit.

Jonathan Wolf: And Tim, the thing is just ballooned up on my arm until it reaches the point when it feels a bit uncomfortable, and now it feels like it's releasing. What's it actually doing right now? 

Prof. Tim Spector: Well, it's stressing the system. It's seeing at what point your blood is pumping through the pressure of the cuff.

So basically, it knows what pressure it's putting in, it's seeing whether your own pressure is greater than that or equal to that. So it's a relative measure of the pressure. 

It's been used for ages. It's not recording the exact pressure inside your whole system, but it's an established way of looking at risk that we base all our treatments on.

So what's it telling you? 

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Jonathan Wolf: So, Tim, let me, let me show you the thing that's appeared up on the screen. 

Prof. Tim Spector: Okay. So that's 118 over 78. That means your systolic blood pressure is 118, and your diastolic, which is the low level, is 78.  

Jonathan Wolf: So what does that mean? Why have I got two numbers for my blood pressure?

Prof. Tim Spector: This is just the way it's classically been done. It's the high-pressure one and the low-pressure one. And at the moment, we record both of these, but the science changes every few years about which they think is most important. 

We currently think that the top level is the important one. That's the systolic level, and yours is below 120. Which means it's normal. 

Jonathan Wolf: Oh, I passed. 

Prof. Tim Spector: You have passed Jonathan. Yes. Actually, on this, you are healthier than me. 

Jonathan Wolf: It's a win, and I will take that absolutely. That doesn't happen very often, so I'm pleased. Normally, I do these tests, and they're like, Oh yeah, blood sugar control is terrible.

Or, Oh, look at all that fat you got in your liver. So I'm quite pleased if I've actually passed a test. 

Prof. Tim Spector: Yeah, you look very pleased about it. So that's great. 

Jonathan Wolf: And do you think if I wasn't on a podcast and I'd just done this sitting calm in the sun, would it have been any lower, or is that whole thing about stress and blood pressure not really real?

Prof. Tim Spector: Stress and blood pressure is real in the short-term scenario. 

So, short-term stress will put your blood pressure up, but it's not the main reason that people have long-term high blood pressure. There are many reasons, it is one of them. 

It's normally things like being overweight, having too much central obesity, having type two diabetes, having a poor diet, not exercising.

It can be due to stressful scenarios as well, but in fact, it's similar risk factors to having a heart attack or having type 2 diabetes. These metabolic risk factors seem to be the major ones, and it has only a small genetic component, so you can't blame your parents generally for your blood pressure.

Now I've got a blood pressure monitor on me, it looks like a wristwatch. These new devices that measure my blood pressure automatically. Every 30 minutes, it goes off. And just by reflecting light against my blood vessels, it gets an idea of what my blood pressure is. 

Jonathan Wolf: And Tim, for people who can't see it on video, I mean, it just looks like a little small wristwatch or like an old little Fitbit with nothing visible on it. Just a band.

That is not inflating like a balloon every 30 minutes and cutting off the blood supply to your hand? 

Prof. Tim Spector: No, it's not. And it's using little light-emitting devices that send light against my skin and against my blood vessels. It bounces back, and it can tell the velocity of the wave and the height of the wave, and the blood vessel.

This has now been correlated really well to blood pressure. So I get a very accurate one just from this. But the advantage of this is although it's not as accurate as the cuff that you've just done, I'm getting 48 results every day, because it goes off every half an hour. 

This is really important because if you're tracking your blood pressure, you want to know not what it does in the best of situations, when you are perfectly relaxed sitting down. You want to know, okay, what's happening in the middle of the night, for example? That's when your body should be at its most relaxed. We think that's the most predictive. 

It's virtually impossible to wake yourself up and not be stressed, and take your blood pressure. So these are really useful for exactly that. And this is new technology, and it's going to be in most people's mobile phones very soon. Just by putting your finger over the lens, you can get a result. 

So this is the technology, and I think it's a change in our mentality, which is blood pressure is saying we should be able to manage ourselves without having to need medical experts in most conditions. Not for severe problems, but this is something everyone should be doing for themselves.

For $20, you can get yourself a really good machine, and you know exactly what's going on. You don't need a health professional to guide you. And so this is why, you know, we're talking about blood pressure and all the things you can do about it. 

Jonathan Wolf: Well, let's say you do have your own machine. What are you looking out for? You just said to me, 118, that's good, but I wouldn't have the faintest idea. So what are you looking for? 

Prof. Tim Spector: Well, you're looking to keep it at 120 or below as an average reading for most of the time. It will depend slightly on your age because it creeps up with age.

If you are 17, you're listening to this, and your blood pressure is 125 or 130, you shouldn't worry too much. But we should always be trying to get it below 120. And many people will be going to their family doctor, and they might be told, Don't worry, we did your blood pressure. It's 130 over 90. It's average for your age. Don't worry about it. 

That still means you have an increased risk of stroke and heart attack, and so we shouldn't be as complacent as we've been in the past. We know that even treating people at these very minor levels of blood pressure is still very useful. And it could be very high. 

So, the other thing is if you do go, or you do it yourself, and you find you are consistently 150, 160 at the top level, then you shouldn't be waiting, you should be going to seek treatment.

Jonathan Wolf: So, for something like that, you go and see your doctor right away. 

Prof. Tim Spector: Right away. Yes, exactly. So the higher it gets, the more immediate your risk of doing some harm to your body, as a heart attack or a stroke. 

Jonathan Wolf: So you're one 130 you're saying, your doctor might say it's fine, but you're saying, well, it is having some impact on health, and we're going to talk a bit about what that might mean and what you can do. 

But you're saying if it's at 150, actually, you just need to go and see your doctor right now, and they will say that's the real cause for concern. 

Prof. Tim Spector: Correct. 

Jonathan Wolf: So why do you get high blood pressure? 

Prof. Tim Spector: We don't really know, is the honest answer. It's a combination of what we call sort of metabolic insults to the body over a lifetime. It seems to be associated with a Western lifestyle, Western diets, and sedentary life. Just a part of living, really. 

Because when you do go to very rural parts of Asia or Africa, and see people living in natural environments, their blood pressure is remarkably low. We're talking, systolic blood pressure less than a hundred.

Jonathan Wolf: So I did well for a typical westerner in their forties or fifties. Not for someone who would be living a… 

Prof. Tim Spector: African nomadic lifestyle 

Jonathan Wolf: With a sort of diet that our ancestors had, and five times more exercise than I'm doing. 

Prof. Tim Spector: Correct. If there is a risk, it's pretty minute. 

Jonathan Wolf: And what about salt? Because I was thinking about… The other thing that came back to me, I thought about it this morning, is, Oh, it's all about salt or high blood pressure. 

So, I'm thinking to myself as a CEO, having, you know, salt on my chips. That's basically it. Is it all salt? 

Prof. Tim Spector: For many years, we thought it was mainly salt, and lots of studies have shown there's a correlation between the amount of salt intake in a population and their blood pressure.

When people shifted to low salt counts, they got lower blood pressure. But as always, in science and medicine, it's more complicated than that. 

It does appear that some people are more salt sensitive than others, which means that salt is more important in their bodies than in others. And for other people, other factors are more important than salt. 

The evidence so far suggests that in Western populations, perhaps about one in four people are really quite sensitive to salt. So that a small change in the amount of salt they're having, whether they're having it on their French fries, or their potato chips, or adding it to their food, makes a really big difference to their blood pressure.

So that if they cut it out, and they go from having, I think the U.S. is around two, two and a half spoons of salt per day. If you cut that right back to what the American Heart Association says, less than one spoonful. So, half a spoonful, you can get quite a big reduction in your blood pressure. 

But the other 75% of the population, when they do that, they're only getting a one to one and a half percent difference in your blood pressure. 

So, for you with 118, you'd only get to 116 if you really restricted your salt intake to just half a teaspoon a day, which might mean that your chips would taste terrible and your steak would be nearly inedible, and you've been making a fairly major sacrifice. So, the latest science is really changing the way we think about this. 

There are also genetic differences. So if you have someone of African origin, an Afro-Caribbean, or an African American, you are much more likely to be salt sensitive. So it could be that well over the majority of those populations are going to see quite a big improvement if they cut back on salt.

This is due to some hormones that control the kidneys. Something called renin that has a big effect. 

I tested myself. So when I had my initial incident where I had my mini stroke, it turned out that increase in my blood pressure over the space of a few weeks. I did try for a month, going on a salt restriction, and it made virtually no difference to my blood pressure.

I was taking it every day with a monitor like the one I've shown you, and it made very little difference. So I'm clearly not myself salt sensitive, and other things are more important for me.

But for someone else, it could be really, really important. So there's really important personalization going on here between these treatments. In the past, we've assumed that we should give the same advice to everybody, and some people even got worse when they salt restricted. 

So if you had type 2 diabetes and you went on too much salt restriction, it could actually get worse, and your kidney function might get worse. So I think we're still trying to find the right balance here in terms of advising populations, advising individuals, 

Jonathan Wolf: But it sounds like it's definitely not all about the salt.

Prof. Tim Spector: Definitely not all about the salt. 

Jonathan Wolf: Are people often prescribed medicine when they're diagnosed with high blood pressure? 

Prof. Tim Spector: They are, and they're very effective if you take them regularly, and most people, unfortunately, are not very good at taking them regularly. That's perhaps one of the commonest causes of failed treatments, people just don't think they need to take them every day.

A combination of these diuretic tablets which means that you pee out more of your fluids, so you are more concentrated. There's calcium channel blockers, which are the other ones. Things like amlodipine are very common. They change the way the vessel dilates because that uses these calcium channels. There's other ones called ACE inhibitors. 

There's a whole four or five classes of these. They're all effective for different people, and again, different drugs. 

We did a big study of this, and there's quite a big difference between… different ethnic groups do better on some than others. 

You may have also heard of beta blockers, which are used to sort of reduce your pulse rate and calm you down. They work very well in some people, but not in others. 

So finding the one that suits you is really important. And again, we know the medicines are also personalized just as much as the dietary advice is personalized. 

So they do work, you've got to take them and you've gotta be really, really fastidious about not forgetting, 

Jonathan Wolf: And are there any risks or side effects associated with medication?

Prof. Tim Spector: All medications come with some risks. But these are generally well managed. 

If you've got very high blood pressure, and you're taking lots of medications, sometimes in certain situations, you might drop your blood pressure, and you might be prone to fainting, collapsing, which can cause injury. That's one of the commonest things. 

Beta blockers can cause asthma. They all can cause different levels of problems in your temperature control, you may have cold fingers. All these kinds of things can happen.

But the advantages far outweigh any disadvantages of the drugs, so there's absolutely no reason not to at least try drugs and see how you get on with them. See if they control the blood pressure quickly and ideally without any side effects. 

Because the risks, if you don't, are huge. Your risks of having a catastrophic stroke or a heart attack are increased exponentially for each just millimeter of your blood pressure going up and how well you can control it.

Jonathan Wolf: What are the disease risks that you face if you are living with this high blood pressure? Sounds like you described it as a silent killer, so very possibly not even realizing it. What might happen? 

Prof. Tim Spector: The classical ones are increasing by threefold your risk of a heart attack, which can come out of nowhere. Your blood vessels and your heart are put under strain, and if that leads to a blockage, you get a heart attack.

Having a stroke. You get three to five times increased risk of a stroke. 

Jonathan Wolf: So these are really big increases. You're saying three times higher. 

Prof. Tim Spector: Yeah, they're not trivial. 

Also, all of these depends on what your level of blood pressure is. The higher it is, the higher the risk.

Because we define someone as having high blood pressure, currently as anything over 130 over 90. But there's a whole range above it, and just below it in that gray area we talked about.

Jonathan Wolf: And are you able to explain in simple terms why my having this higher blood pressure increases so massively those risks of heart attacks and strokes? 

Prof. Tim Spector: We don't know the precise details, other than those organs are under strain and stress. Because as I said, if your blood pressure is high, that means also that you develop increased rigidity, less flexibility of your blood vessels. So they can't respond easily to any stresses in the system as much as they would. They can't cushion it. 

Because, you know, in a way, we are often repairing our own blood vessels all the time as the blood is flowing through it. And if you've got these stiff, rather rigid ones, instead, they can't do as good a job at repair.

So they more easily get blocked, more easily get inflamed. Inflammation attracts clots and other things to it. 

In your brain, the blood vessels can either form a clot or they can actually bleed. So they can get a little stress in the blood vessel, and you get a hemorrhagic stroke.

And we also know that it's also related to a whole range of other metabolic conditions. So dementia is something we mentioned at the beginning. People often think of dementia as purely Alzheimer's disease, but at least a third of dementia is related to blood vessel disease. 

So the bits of the brain are not getting the same level of energy intake, nutrition they would get because of the state of your blood vessels. Because of this constant pressure they're under due to the high blood pressure. 

Jonathan Wolf: And so, Tim, just to make sure I've got this, it's not just that it can create that sudden catastrophic heart attack or stroke as a result of this pressure being so high, there's also a slow, long-term impact. 

You're describing something like dementia, which I think I know from some of these other podcasts, it doesn't just happen in one day. It sort of happens over time, and the blood pressure is causing damage over time?

Prof. Tim Spector: Yes. So it causes metabolic upset. It also causes inflammation, and just the body's having to work harder and harder. So everything gets less efficient. 

And this is the common theme we keep talking about. This is why high blood pressure is part of metabolic syndrome, that yes, if you have type 2 diabetes, you're more likely to have high blood pressure.

But it also works the other way around as well. If you’ve got this defect in your blood vessels that causes stress to all your cells, and the way they're pumping out energy, and using fuel in all the organs in your body, it makes you more likely to have kidney disease. Makes it more likely to have brain disease in terms of dementia. And affects all, all bits of your body to some extent. 

So it's not just a sudden yes or no, I'm going to get a stroke or not. It has a really harmful effect on many aspects of your body.

It needs to be seen as a metabolic disease rather than as a purely one-off thing on its own. It's a sign that your body's not healthy. 

Jonathan Wolf: So it's both a sign that your body's not healthy, but it's also a risk factor that can then cause something. So you were saying it might come from type two diabetes, but it also might be something that causes you to get type 2 diabetes. 

Prof. Tim Spector: Correct. 

Jonathan Wolf: You've mentioned dementia and type 2 diabetes. Are there any other diseases that we now know to high blood pressure, beyond the stroke and heart attack, that I think was our common knowledge in the past? 

Prof. Tim Spector: So, as well as kidney disease, you've got eye problems. It's related to macular degeneration of the eye, which is often caused by blood vessels in the eye not being flexible enough, and that is a common cause of blindness.

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Hearing loss, again, the microvasculature of the ear is related to that, and it can also cause a really annoying perception problem in the ear called tinnitus, where you get a low-level buzzing, which is extremely unpleasant to have. 

So lots of both minor and major problems, all associated with a failure to really control our blood pressure.

Jonathan Wolf: So it definitely sounds really serious. It also sounds like lots of people listening to this podcast, when they go and get themselves measured, will discover their blood pressure is higher than they thought it was, higher than this sort of healthy range. 

If they then reduce their blood pressure, is it too late to fix any of the damage? Or if they reduce their blood pressure, does that reduce the risk of all these diseases in the future, even if it's been high in the past? 

Prof. Tim Spector: It's never too late to reduce your blood pressure. I think that's generally the case, apart from people maybe in their hundreds. 

For most of us, even if you've not known about it for 10 years, you'll still get enormous benefit from getting that blood pressure down to that 120 over 80 range. 

Where you will start to see the benefits, and your metabolism in your body will improve. The inflammation will improve. Your risks will suddenly drop for many of these conditions. 

Some of the damage will be done, but you'll still be protecting your future life in a big way if you take action. So I think you have gotta be very positive about this and not think about the past, think about the future in your future years. 

Especially, you know, I've seen my mother have a stroke. She had poorly controlled blood pressure, and we all know people like that. And it's such a preventable condition that we really all need to be taking much more care of our blood pressure.

Jonathan Wolf: So, if you don't mind my asking, when you talk about that example with your mother, are you saying that you feel that if she'd managed to control her blood pressure better, she might not have had that stroke? 

Prof. Tim Spector: I think that's correct. Yes. The data show that if your blood pressure is well controlled, as opposed to poorly controlled, it can halve your risk of having a stroke.

You can never eliminate the chance completely, because sometimes people have stroke without having high blood pressure. But you can dramatically improve the odds. 

I think she used to wait and go and see her GP every couple of months and get a blood pressure check. But, she didn't have the technology we've got now, where we can do this every day ourselves, and we know how important it is to take the tablets at the right time in a way.

Fine-tuning your medication to the blood pressure is really important, and how the new insights we've got about trying to work out what your blood pressure is at night, when you're in your supposedly totally relaxed state. 

We can optimize things now in a way we couldn't do before. We know much more about it. It was a very blunt instrument before, and people used to put off seeing their GP because there was they couldn't get in, and they say, go a year later and their blood pressure's through the roof and some damage has been done. 

Jonathan Wolf: Tim, the team said I should ask you about a very unusual study that you were involved in, looking at the relationship between blood pressure and the gut microbiome.

Prof. Tim Spector: Yes, that's right. 

So about five years ago, we combined my twin cohort from Kings, which is a group of thousands of twins we’ve been looking at for 30 years. We have very good blood pressure data, and we had their gut microbiome readings. 

We combined that with some ZOE members that we also had reported having high blood pressure, and we knew also knew their gut microbiomes.

We put these together and found that people with abnormal gut microbiomes, unhealthy gut microbiomes, nearly always had higher blood pressure than people who had normal microbiomes. 

So, regardless of whether in the U.S., the U.K., twins or not, there was a very consistent message here that the microbiomes were abnormal.

We found certain ones that were high in people with hypertension, certain microbe species that were affecting some of these renal pathways. So it looks like the chemicals some of our microbes are secreting could be very powerful in protecting or increasing our risk of having hypertension, high blood pressure. 

Jonathan Wolf: Were you surprised by that? Because I have to say, somehow, the idea that your microbiome is affecting your blood pressure, which sounds like something somehow to do with your heart, seems a bit crazy.

Prof. Tim Spector: I was more surprised five years ago than I am now. 

But now the ability of the gut microbiome to influence everything in our bodies doesn't seem to be quite as crazy. We also realize they secrete all kinds of chemicals. Our bodies and our kidneys, which control all of our blood pressure, are very sensitive to these chemicals.

And so it now makes perhaps more sense than it did then, and I think we realize that there are lots of pathways going on that we need to control to get the ideal blood pressure for our environment. 

This is what it's doing. And it sort of makes sense that the gut is, in a way, a bit acting as a bit of a sensor for what we're eating and then putting out chemicals to try and do what it thinks is the best way for our body to react to that food and that environment. 

And it comes back to this idea you were talking about salt, is this the only thing? Clearly, it's not. The pathways we're seeing weren't just salt pathways. Other studies have now shown that, as well as salt being important, things like potassium are actually even more important.

Potassium is another key element that is important in how much water goes in and out of a cell. Studies have shown that it's the sodium-to-potassium ratio that's much more important than just salt on its own. Remember, salt is sodium chloride. 

So in the U.S., they always talk about sodium levels. In the U.K., we talk about salt levels, but we're essentially talking the same thing. 

It looks like from these trials, where they've observed potassium and salt intakes, that potassium intake has an even bigger effect than salt. 

Jonathan Wolf: Potassium is bad for you in the same way that salt is? 

Prof. Tim Spector: No, it's good for you. So it's acting in the opposite direction. 

So if I want to reverse high blood pressure, I want to increase your potassium intake. And you do that classically by giving you some bananas, which have a reasonably high potassium, but also things like kiwi fruit have even more, and most green leaf vegetables also have high potassium.

So people on vegetarian diets, high plant diets, are naturally getting a lot of potassium. And this is another reason why your holistic diet is perhaps more important than just whether you're getting a lot of added salt. 

Jonathan Wolf: So, Tim, I would love to switch now to that actionable advice. Because I think you've painted a picture where you're saying your blood pressure is really important. 

You should know your blood pressure reading. If it's high, you need to do something. That it can have a really bad impact if you don't. 

So I expect lots of people listening are saying, one, I should go out and buy one of those blood pressure monitors, but number two, you know, what can I do in addition to, or instead of, going to the doctor to take a pill?

Is there anything that people can do in terms of their lifestyle? 

Prof. Tim Spector: Absolutely. Yes. So lifestyle changes, as we've discussed many times, are important. 

So if you are too sedentary, that's going to put your blood pressure up. So, try and do some exercise.

Jonathan Wolf: Sedentary is doctor speak for sitting on the couch.  

Prof. Tim Spector: Sitting on your bum all the time. Yeah, exactly. Modern lifestyle, working at home, is very bad for you. Get out there, do some walking, do some exercise, that's good for blood pressure. 

Sleeping well is also related to blood pressure, so sort out your sleep as much as you can.

Jonathan Wolf: That's not just one of these sort of hand-wavy things. Your sleep really has an impact on your blood pressure. 

Prof. Tim Spector: Yes, it does. And again, we see this repeated because blood pressure is part of this metabolic group of conditions that all seem to have similar causes. 

A poor night's sleep or doing lots of shift work will actually raise your blood pressure. So, particularly if you are doing night work, shift work, you are more prone to these problems. So it is a risk factor generally. 

We did sort of laugh off stress, but if you've got chronic stress in your life, then that is associated with blood pressure in many studies. And try and find ways of reducing that through something you enjoy. Whether it's sport or it can be something like yoga, it can be like meditation, it can be through having sauna. 

There have been some small studies showing that people who have regular saunas do have lower blood pressure. It sort of makes sense because you are expanding and you are stretching your blood vessels when you're going for a sauna. They're trying to keep up and keep your temperature constant, so they're having a little workout. 

Jonathan Wolf: This is like the gym for my blood vessels, is just to sit in a sauna and sweat. 

Prof. Tim Spector: Correct. Yes, exactly. 

Jonathan Wolf: I love that. It's definitely less painful than the ice bath. We know that's not my thing.

Prof. Tim Spector: I know you prefer sauna to ice bath. But in the same way, mindfulness and yoga do relax you, and you will get some benefit from that as well. 

But I think the main thing we should focus on, that everyone can do, is to think what in their diet can they do to get their blood pressure down?

Because every millimeter counts. 

Jonathan Wolf: So, can we start to dive into diet then? Maybe start with what might be causing the problem? What in my diet might be raising my blood pressure? 

Prof. Tim Spector: These would most likely be processed foods that have high salt content. 

We think that about 85% of the salt you get in the average American or British diet comes from prepackaged, manufactured, highly processed foods.

Jonathan Wolf: So, almost all the salt does not come from when you pour salt onto your meal. 

Prof. Tim Spector: Unless you live and work in a French restaurant, then it's only about 10% of your intake. 

It varies a bit, but it's at most 20%. So, at least 80% is coming from prepackaged foods that you are buying. Whether in canned soups, whether they're in biscuits, they're in muesli, they're in children's cereals. Things that you don't expect to find so much salt. 

Jonathan Wolf: And is that more salt than we would've put in our diet in the past when people would've just been cooking their own versions of these meals? 

Prof. Tim Spector: Much, much more. Yeah. It's three or four times more, we're getting, and they're often doing it to disguise some of the other flavors.

Salt is used to disguise a lot of the chemicals that they're putting into these foods. It's also there to provide this hyperpalatability. This is a term we've talked about to make you overeat. 

So by adding a certain amount of salt to things, if you combine that with salt and fat in these foods, you will naturally overeat and therefore spend more money on that company's product than you would otherwise have done.

Jonathan Wolf: So this is a big part of what Big Food is putting into these meals, either to hide the ingredients that you might taste, and don't taste as nice, or just to make you have that thing where you just can't stop eating. 

And it's sort of that magic point where it's so delicious that you're just going to eat the whole pack.

Prof. Tim Spector: Correct. And it's obviously so vital to their product. They really haven't worked out a way of doing without it. So, it's the number one thing that we should be avoiding. 

And the worst thing is it's in many children's products, and things you don't even think are salty. I mean, I don't normally think of cookies or biscuits as needing salt in them, and yet there they are with the sugar, you've got the salt.

It's often used to preserve them for even longer shelf lives as well. So that's where most of the salt comes from.

I don't think there's any harm in telling everybody who's worried about their blood pressure to avoid those kinds of foods. 

Because even if it doesn't dramatically reduce your blood pressure, if you're not particularly salt sensitive, you get so many other benefits from not having those kinds of foods anyway. So I think everyone should be doing that. 

The second thing you can do is, if you do find yourself adding a lot of table salt to your food, you're someone who likes that, you might want to switch to a different type of salt called potassium chloride. 

So this is sometimes labeled as a low salt alternative. So salt has the chemical formula sodium chloride, and these low-salt salts are potassium chloride and they basically mix the sodium chloride with potassium chloride to give you a similar taste, but much less of the sodium, more of the potassium. 

When they've done clinical randomized controlled trials of this, they show that if you switch this around, and you're not having all the other sort of junk foods we talked about, you can reduce your blood pressure by about 3% to 4%. So, more than just reducing salt on its own. 

So that's a pretty good tip. The only problem is for many people that has a rather metallic taste. And they don't like it, but this is what manufacturers should be doing. They should be putting much more potassium than sodium into these prepackaged foods, that would really help make them less harmful for us. 

The other big thing is realizing that just by increasing your potassium level, you will be improving your blood pressure. You'll be reducing it.

The best way to improve your potassium level is to eat more varied plants. I'm not into superfoods, I don't think people should be eating tons of kiwi fruit necessarily. But that's a good example of one that is full of potassium. 

But fruits and vegetables, in their natural form, are fantastic sources of potassium that we should all be eating more of, and less salty things, and just change that ratio. 

The more you do that, the more you'll be able to improve your blood pressure naturally. Even before you're going on to blood pressure medications. And they can also enhance blood pressure medications. 

So it's not either or. I think even if you're on a blood pressure medication, the more you can help it with diet, the less you need to go onto higher doses or a second one, which would give you more side effects, et cetera, the better you'll be. 

Jonathan Wolf: So you feel like combining this with medication makes sense. This isn't something where just popping the medication sort of solves the problem for everybody. 

Prof. Tim Spector: Absolutely. Yes. So I think they should be used together. 

I think we should be seeing diet as another arm of medication, not as a complete alternative, only if you don't believe in medication. 

Because for this particular condition, the evidence is so clear that medication will save your life, and will stop you getting a stroke and heart attack. 

So I don't want anyone to think that this is instead of. It's usually in addition to. It might mean that you can eventually, you might be able to get off your medications.

If you're someone who started them when they're on a really poor junk food diet. Your doctor didn't tell you that the reason was that you were getting all these terrible blood pressure-inducing effects from the food.

You've changed that you've improved your life, you've improved your gut microbes, they're secreting other chemicals. You might then be able to wean yourself off these drugs. That's possible. 

I've certainly heard stories of this from people who've written to me, so bear that in mind. But you know, do that under Medical Supervision.

Jonathan Wolf: And Tim, is it just reducing your salt and increasing your potassium through certain plants that will reduce blood pressure, or is there anything else around diet that can affect your blood pressure? 

Prof. Tim Spector: It's quite likely that we haven't proven it yet, that improving your gut microbiome generally will also have this effect on reducing blood pressure.

So that's why there've been various studies of fiber, for example, showing that if you give people high fiber diets, generally their blood pressure will drop. We think this is again through the gut microbiome.

There's also studies of probiotics. A number of trials have shown that probiotics, which are these live microbes you could have, can reduce your blood pressure, again, likely through the gut microbiome.

Fermented foods, as well, have been shown in a few small studies, not large ones, again, to have this effect. 

So I think a number of mechanisms, you know, reducing salt, increasing potassium, improving your gut health. All of these have been shown to have important effects on your microbiome. 

Jonathan Wolf: So I think you're saying there we know that a diet that's really good for your gut is really good for your overall health. 

It sounds like you're saying you would expect that to impact blood pressure as well. Blood pressure isn't just driven by the sort of sodium and potassium that you've been talking about earlier. 

Prof. Tim Spector: Yes, it's much more general, and it comes back into this idea that it's part of these metabolic diseases.

So just as you improve your gut health, you're going to improve your metabolic health, reduce your insulin resistance. You're going to perhaps start to reduce your internal fat levels. 

All these things that have an impact on your body that's also going to help your blood pressure as well. 

So, increasingly we're seeing these very common patterns of diseases we thought were very distinct or having common causes, and common treatments.

Jonathan Wolf: Listening to all of this, and coming into this podcast, knowing almost nothing about blood pressure, Tim, I'm struck that you've talked a lot about salt on the one hand and how 80% of that is in this highly processed food. 

And on the other hand, moving to a really plant-rich, diverse, and gut-healthy diet can really help blood pressure.

I guess that makes me want to ask how big a role is the highly processed, you know, food in a packet the week today, playing into high blood pressure, and I guess, does that mean is there more high blood pressure now than there was, you know, 50 or a hundred years ago?

Prof. Tim Spector: Definitely. Our blood pressure has been, our average blood pressure has been creeping up every decade since we started doing surveys and measuring it.

I think our poor food environment is probably the number one factor in that. And as always, in nutrition, we've tended to overfocus on one element, and that's been salt.

I think we’ve been blindsided by that, because most people who restrict their salt intake are not going to get very much benefit if that's all they focus on. 

There'll be, as we said, [people of] African origin, or one in four people will get a benefit, but most will only get a small benefit.

If they took a more holistic view and saw that, okay, what are the other things in the food that are causing these problems indirectly, say through the gut microbes or making their metabolic health worse, then they'd be much better off.

Because it is clearly correlated with poor diets, poor environments, poor social class, all these other elements that are not just about salt. 

Jonathan Wolf: Final question, because we brought up at the beginning, you haven't mentioned beetroot juice, but it came up in the questions at the beginning. 

Prof. Tim Spector: Beetroot juice is one of those plants that is really interesting, and it has a special effect on blood pressure.

So they've actually done quite a few studies of giving people beetroot juice, and it reduces your blood pressure three times more than salt restriction. 

Jonathan Wolf: Three times more than salt restriction to have beetroot juice?

Prof. Tim Spector: Yes. Most of the studies show, on average, about a 4% reduction in your blood pressure.

And this is because it interferes with nitrates in your blood. And these have really big effects on your blood vessels. 

They were giving people a large glass of beetroot juice, which would probably be a large beetroot today, which is probably more than most people would normally eat.

Jonathan Wolf: And is beetroot juice a sort of concentrated beetroot, or is that just… am I getting more beetroot out of a beetroot juice, or actually is it sort of watered down? I don't think I've ever had a beetroot juice. 

Prof. Tim Spector: I think you just mash it up into a smoothie and then dilute it. I don't think it matters whether it's the juice or if you're actually having fresh beetroot. 

It's full of really good elements, including it obviously has potassium in it, but it has these nitrates, which have this very special effect, in addition to the blood vessels themselves.

So, I think it's another reason to include beetroots into your diet, particularly if you do suffer from high blood pressure. Have them in salads, but probably if you're having it three times a week, I imagine you're going to still get some benefit from it. 

No one's done these large studies, and of course, as always, it's going to vary by individual.

Jonathan Wolf: Brilliant. So, Tim, it's the first time we talked about blood pressure. So I'm going to try and do a quick summary. 

So the first thing you said is it's a silent killer. You're not actually aware if you have high blood pressure. 

It's going up every decade, so this is getting worse and worse. So make sure you get yourself measured. You can get a device for  $20, £20. Measure yourself regularly. 

Even if it turns out that your blood pressure is currently high, actually, if you reduce it, you can have a big impact in terms of reducing your risk of very serious diseases and death. 

In particular, you talked about your own story with your mother having a stroke, and the risk of a heart attack. There's a very serious risk. 

Diet can have a big impact on this. It's not just medication. If you want to do something fun, try beetroot juice. 

If you're thinking a bit more broadly, then yes, you want to eat more things with potassium, and we now understand that that's very important. 

But you also want to reduce your salt. But it isn't going to be the salt that you're adding into your diet by pouring salt onto a meal. Almost, I think you said 80% of the salt we now eat is in this highly processed food, generally in the sort of highly processed food that's really bad for us, and they're putting it in there to sort of hide all the other chemicals and additives that they put into it. So it tastes good, and it also probably makes you eat this more often. 

It's not only however diet, you also said exercise can have a big impact, and for many people who are not really doing any exercise, that shift even to a moderate amount of exercise could have a big impact on blood pressure.

Sleep interestingly also affects it. And finally, rather to my surprise, you said chronic stress can affect this. 

There is some sort of limited evidence, but you said some real evidence that if you can find ways to reduce your stress, sauna,  maybe even meditation, that could potentially also have an impact on your blood pressure as well.

Prof. Tim Spector: Absolutely. Yes. 

Jonathan Wolf: Wonderful. Well, we will measure my blood pressure again now at the end of the episode, and we'll see whether or not I've managed to lower or raise my concern while being told about all the terrifying things that might happen if my blood pressure went up. 

Prof. Tim Spector: And we can celebrate with the beetroot juice.

Jonathan Wolf: Let's go and do that. Thank you very much, Tim. 

Prof. Tim Spector: Pleasure. 

Jonathan Wolf: If you enjoyed this episode with Tim about high blood pressure, I know you'll love watching this conversation with Dr. William Lee, explaining the best foods to keep your heart healthy for years to come.