194-Fructose Dangers
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Welcome back to the Health Longevity Secrets show with your host, Dr. Robert Lufkin. His book titled Lies I Taught in Medical School is now a New York Times bestseller. See the show notes for a link to download a free chapter. And now please enjoy this week's episode as we take a deep look at the dangers of fructose with Dr. Richard Johnson.

This week, we get to unlock the secret to better health with Dr. Richard Johnson, a leading mind in the field of sugar metabolism, as he reveals the hidden dangers of fructose and its surprising role in metabolic diseases. We hear so much about fructose. Is it good? Is it bad?

Well, this week we dive into the science of sugars and uncover the biological mechanisms that make fructose a stealthy culprit for obesity. While fruits like dates and figs may seem harmless, their high fructose content is a concern, especially when consumed in juices. Dr. Johnston demystifies the connection between sugar and fat storage and why the body mistakenly believes it's low on energy, leading to weight gain.

We get to explore the fascinating interplay between fructose, salt, carbohydrates, and learn how these elements influence blood pressure and metabolic health. Almost half of us now have high blood pressure or hypertension.

We discover why a low-carb or keto diet might be the best defense against the adverse effects of both salt and uric acid. We also navigate the world of sugar substitutes with a spotlight on allulose, a promising alternative. We finally discuss Dr. Johnson's informative book, Nature Wants Us to Be Fat, for further reading on this critical healthcare topic.

This episode is sponsored by Cypox Health. One of the most common questions I get asked is which blood tests I check myself on a regular basis. Well, I check 17 biomarkers, but the secret is I'm able to do everything from the convenience of my home. I collect the sample with

Just a simple finger stick like this. You don't need to be a doctor to do it. Then I just mail it in and wait for the results. CyFox Health makes it possible. Use the link below to get 15% off. This episode is brought to you by El Nutra, maker of the Prolonged Fasting Mimicking Diet. If you'd like to try it, use the link in the show notes for 20% off. And now, please enjoy this week's episode. Hey, Richard, welcome.

Thank you. It's great being on your show. Yeah, I'm so excited today to talk about just getting to your expertise about sugars and fructose and all these different things. But maybe we could just start off by telling people what exactly is fructose compared to other sugars and yeah, what is it? Yeah.

Well, at a very simple basis, fructose is a sugar. It's the sugar in fruit and honey. So we think of it as healthy, but it's also a major component of table sugar and of high fructose corn syrup. And most of the fructose we get in our diet

comes from those two added sugars and table sugar is sucrose, which is glucose and fructose combined together. And high fructose corn syrup is glucose and fructose mixed together. And our work suggests that fructose is really the culprit that is driving metabolic disease. And, uh,

So that's very briefly, you know, about it. By far, the majority of our fructose that we eat comes from table sugar and high fructose corn syrup. Probably, you know, 15% of our diet or so comes from these sugars.

Yeah, that's fascinating. So to reiterate then, when people talk about sugar, table sugar, it's a combination of glucose plus fructose. And a lot of times when people are worried about glucose as being the bad sugar or the glucose spikes and all with insulin and with diabetes and everything. But what you're saying is that

in your opinion, that the fructose is what we may have to worry about as at least an underappreciated driver of metabolic disease. And then the last point is that fructose, we not only get it from fruit, but it's also a major component of all the processed junk foods that are ubiquitous today that make up most of our food supply. Yeah.

Yeah, the vast majority of the fructose we get comes from sugars, not from natural fruit. And natural fruits contain other substances that actually make the natural fruits very beneficial. Natural fruits contain antioxidants like vitamin C. They contain flavanols like epicatechin. They contain potassium and they contain fiber.

And our group has shown that those substances actually counter the effects of fructose. So when you eat a natural fruit, the fructose makes it taste delicious, but it's not going to do much bad to you. The fructose isn't going to do anything bad to you generally with fruit because of all the good stuff in it that counters the effects of fructose.

to activate these pathways that can cause obesity. So natural fruits are actually recommended, but I don't recommend drinking fruit juice because you have more than one fruit in a cup. You may have like four or five so that the concentration of fructose can suddenly get pretty high. Likewise, there are a few fruits that are extremely rich in fructose like

dates and figs and those i would not recommend either so so glucose and fructose are very similar um molecularly i mean they have the same number of carbons oxygens and hydrogens but how are they different they're both sugars what's the difference between them well there's a huge difference between them and um and so let me just try to explain the difference and then i want to uh

throw out a twister for you. So the, the, the big thing is, you know, what drives obesity? How is obesity driven? And in essence, you know, think of fat as a, you know, as something that's like a stored energy. And let me explain how that works. So

Quickly, you know, when we eat food, we're eating calories and the calories are called calories because they help generate energy in our body. That energy is called ATP and it's produced by mitochondria, these little factories, and the ATP gives us the energy to do what we want to do.

So everything's about making sure we have enough energy, and that energy directly relates to the food we eat, which provides the energy. But if we don't have food around, we have to get our energy someplace else, and that energy we get from fat.

So when fat is sort of a form of stored energy, because when you break down fat, you can release that same energy, that ATP. So when you break down fat, you can produce ATP from that. And that can replace the ATP in the food we eat. So we have to have ATP.

So most foods, when we eat them, they're used to make ATP. And then if the tank fills with ATP, then the rest goes to fat.

And that's the way everyone viewed obesity. But the way actually what drives obesity is really not that simple. What happens is we drop the ATP in ourselves to create the sense that we are low in energy. And by dropping the ATP, it starts off an alarm that makes us hungry and wants us

Makes us want to eat more and so forth. So the trick to creating obesity is to drop the ATP, but not let the fat replace it, you know, break down a fat, replace it. So what fructose does is it actually suppresses the production of ATP by those little mitochondria so that your ATP levels go down.

while at the same time blocking the ability of fat to release or to break down to make ATP. So it creates a low ATP state, even though your total energy is still good because you've got all that stored energy. And so when you eat food, instead of going to make ATP because that suppresses the energy preferentially, it goes to fat.

And that's how fructose works. And it's a very significant biochemical pathway. It involves a substance called uric acid. Uric acid is the key to suppressing the ATP production. So the uric acid is really important. David Perlmutter wrote a book on uric acid called Drop Acid that I recommend. And my book, Nature Wants Us to Be Fat, also talks about this.

But anyway, so fructose lowers ATP, makes you hungry. Glucose raises ATP. If you inject fructose into the brain of a rat, it will drop its ATP, it will become hungry, and it will eat immediately. If you inject glucose into the brain of a rat, ATP levels go up and it feels satisfied. So there's a huge difference.

But here's the twister. There's always a twist. So the twist is that the fructose that's in our body, it doesn't just come from what we eat. We can also make fructose, and we do. And this wasn't appreciated, but every month or every few months, there's a new paper coming out showing that humans make fructose, and we make it only one way.

We make it from glucose. So we come back to the glucose as a source for making fructose. It takes a while though. If you, like when you inject glucose into the brain, it takes like 45 minutes before the fructose is made. So that's why you can get these immediate effects with glucose raising ATP. But over time, high glucose will stimulate fructose production.

And the biggest way is when you eat foods that are very rich in starches, starchy foods like potatoes and rice and bread will raise your blood glucose. You know, this is what stimulates insulin. So you eat these foods, your blood glucose levels go up. Insulin is secreted. Insulin

drives the glucose into the cell, generates some fat in the process. And that is important. That is a mechanism for putting fat in there. But then the glucose, when it's high, also gets converted to fructose

And over time, fructose causes insulin resistance that keep the insulin levels high all the time. So you don't have to eat the food to, you know, to have that high insulin level. You now have a high insulin level all the time. And so they work together. And when you get a soft drink, which is made with high fructose corn syrup,

You've got all this fructose, which is bad, right? It's driving obesity. And you have all this glucose, which is stimulating insulin and being converted to fructose. That double whammy is really what makes soft drinks so dangerous. So again, the main problem is fructose. Insulin, of course, is playing a role.

in both glucose and fructose effects, but the main problem seems to be fructose when you look at the overall picture. And it's coming from carbs,

from the fructose we eat and the fructose we make, which is basically from carbs. And that's why a low-carb diet is so beneficial because it kind of removes not just the fructose that we eat, but the fructose that we make. By being on a low-carb diet or keto diet, there's not a lot of glucose around to be converted to fructose.

Yeah. Hey, I wanted to give a shout out for your book too. This is a great book. It's my favorite book on fructose and get it. It's written for, it's understandable for a lay audience, but it's also has some great information for professionals as well. It's a super book. So fructose is,

I guess the dangers of fructose, it's not, if we want to avoid the problems with fructose, it's not enough just to minimize kind of minimize the junk foods and the fructose consumption. What you're saying is even glucose consumption.

can be converted into fructose in our bodies. And so really, what you mentioned was a low carbohydrate diet, low starch, low sugars of any kind, a ketogenic diet, if you will, will then keep the sugar low, both glucose and fructose for us to do that.

Now there's some other, there's some other, uh, aspects to that. And one is that, um, the, the, the way the fructose is converted or the glucose is converted to fructose is through, uh, a chemical pathway. And we call that pathway, the polyol pathway. And, um, that pathway can also be stimulated by, by certain foods. So, um,

So foods like salt can stimulate the conversion of glucose to fructose. And things like uric acid, the guy that

So uric acid is involved in the way fructose works, but uric acid also has this feedback system to try to stimulate fructose production by stimulating those enzymes that convert glucose to fructose. And so alcohol can generate uric acid in certain foods, umami type foods and high purine foods can generate uric acid. But interestingly,

When you're on a low-carb diet or a keto diet, salt and uric acid really can't do that much because the primary mechanisms that those guys work is to convert the glucose to fructose. But if you don't have a lot of glucose around because you're on a keto diet, then you can have a high uric acid or be eating salt and you're not going to be generating

generating a lot of fructose. So where salt becomes bad really is when you are eating a lot of carbs. So like if you eat French fries versus regular potatoes, the French fries are going to be much more dangerous because the salt in the French fries helps convert the starch to fructose so that it's like a double whammy. You're getting the glucose,

from the potato, but then the salt on the French fries is actually helping to stimulate the production of fructose from the starch. And then all that oil and fat on it actually is also bad because

the fructose makes you hungry, so you eat more. And when you eat more, having fat around actually makes you gain weight quicker because fat is a lot more calories per gram than other foods. So fat combined with fructose is a really terrible combination because the fructose makes you eat more than you should. And the fat is like a way to really drive weight gain. And so

Interestingly, you know, if you're on a low carb diet, then you don't have the fructose and you can eat a high fat, high protein diet and you won't get fat despite being on a high fat diet because you don't have the carbs to make you hungry. You know, the fructose to make you hungry. So it's sort of a trick. And the energy balance people who say, hey, it's all calories.

They're sort of right in that weight gain is driven a lot by calories. And so fat really is important in weight gain. But

The trick is that you wouldn't be gaining weight if there wasn't fructose and carbs around. So the carb people are also right by telling you to go on a low-carb diet. And so we recently wrote a paper where we showed these two different theories that are supposed to be completely incompatible actually fit together based upon this fructose story. That is fascinating. I want to circle back to one point you made about fructose

driving uric acid, which then is related to blood pressure sort of in conjunction with salt or even independent of salt through, I think it's through the endothelial nitric oxide synthetase, the blood vessel dilators. So

We're always told to avoid salt for hypertension, but what you're saying is that's only in conjunction with a carbohydrate load. If you're on a low-carb diet, the salt may be less harmful, but should people avoid fructose if they're hypertensive? Is that a recommendation that you would support? Yeah. If you eat sugar, your blood pressure is going to go up, and studies have shown that if you

and give yourself fructose, blood pressure will go up immediately. Whereas if you give yourself glucose, it will not. And we have done studies where we've given fructose to people or like fruit juice, which is high in fructose and your blood pressure will go up quite, quite a bit. And interestingly, when we, we also studied salt,

And when we give salt to animals, they will become fat over time because like laboratory mice are normally eating like 50% carb diet and that's way too much carbs. And that's what we're eating. We're eating 50% carbs. And if you give an animal salt over time, they become fat and they become diabetic and they become hypertensive. So salt,

is sort of like sugar in the regular diet. If you're on a high salt diet and you're eating a lot of carbs, you're going to get into trouble. But now, interestingly, if we block fructose, and in animals, we can actually block the metabolism of fructose. People are trying to make drugs to block fructose metabolism for humans, but they're not ready yet.

But when you block fructose metabolism in an animal, then they can eat all the salt they want and they won't get hypertensive. So the way the salt is causing hypertension actually involves producing fructose. So if you eat fructose, your blood pressure goes up. If you eat salt, you actually make fructose and your blood pressure goes up. And so sugar is really important.

in, in causing high blood pressure. And there's data showing that if, if you go on a low sugar diet, you can lower your blood pressure. So sugar and salt are kind of working together on blood pressure. And if you have high blood pressure, try to cut out soft drinks and liquid sugar for sure. Try to do that. And it will help you and drink more water, actually drinking water

is an antidote to this salt because the way the salt works, the way it generates fructose is to increase the salt concentration in our blood. And if you would eat salt and drink water at the same time, you won't reduce fructose. As soon as you get thirsty from eating salt, you're actually making fructose. So...

So salt is kind of an interesting thing. It's high salt diets aren't good and drink more water. And if you do need salt, if you, you know, like you're sweating a lot, you need to eat salt, do so, but drink water with it so that you don't get high salt concentrations. Thank you for the reminder. You're welcome.

Much better. Yeah, I'm glad you're drinking water. Another thing is to drink coffee. I drink coffee a lot. I do too. No brand here. Well,

Well, in our last, in our last minutes, I wanted to shift to, let's say, okay, I lower my salt, I lower my, I avoid sugars, glucose, fructose. Now there's a whole, a whole field of sugar substitutes that are chemicals that taste sweet. What, what's the story on those? Which of those are good? Are they good? Do they work? Which ones work? Which ones don't work?

Well, we have studied them in animals and looked at it. And the first thing is that there are some sugar substitutes that actually can generate fructose. So the first thing is you don't want to eat a, quote, safe sugar that can make fructose in your body. And the one that's the most commonly used

uses sorbitol, and sorbitol is often added to syrups. So if you get like a low sugar syrup at IHOP or someplace, it'll probably have sorbitol in it, and sorbitol can be converted to fructose. So it's not great. So that's, you know, you know, sugars like sorbitol should totally be avoided. Then there are these artificial sugars that

have been associated with lots of side effects and toxicities. And, um, and so there's concern, for example, saccharin has been associated with bladder tumors and, you know, so that's one that I would avoid. Uh, you know, some that seem to be a little bit safer are things like stevia, uh, and Splenda or sucralose. They seem to be a little bit, but, um, but the

you know, they're still, they're not really positive. They're not really doing good things for you, but they, the data shows that, you know, they don't tend to cause obesity. So this is really, they're neutral. They're not like sugar. So if you had to pick between eating sugar and eating food with Splenda or Stevia, definitely pick Splenda or Stevia. Now there is,

you know, some movement to trying to find low calorie sugars that may be beneficial, may actually help you lose weight. And disclosure, I was approached by a company called RX Sugar last summer because they have a low, a natural sugar called allulose that

which is now on the market. It's generally regarded as safe. So it's approved for people and you can find it in stores. And allulose looks like fructose, but it doesn't activate this biologic switch. It does not cause a reduction in this ATP. Okay.

And so it looks like a kind of a safe sugar. And what's remarkable about it and the disclosure is that this company asked me to be their chief scientific officer and I agreed. And the reason I agreed is because this sugar looks like it has some beneficial effects. And then when it's given to people, it tends to lower plasma or blood glucose after a

a meal. So if you eat like a bread or something, normally your blood glucose would go up and you know that's bad because it stimulates insulin and it can be converted to fructose. But when you eat allulose, the blood glucose doesn't go up or it only goes up a little. So it looks like a low calorie sugar that may be beneficial. And it also has this really cool feature where it stimulates GLP-1, which is that hormone

that people are taking the medicines like Ozempic, semaglutide, some of these medicines to lose weight. And the way they work is they stimulate this hormone GLP-1, but they have lots of side effects, as you know, and there's lots of issues with these drugs. But allulose seems to stimulate the natural GLP-1. So it just gives you a stronger response when you eat than when

than other foods. And that seems to be associated with weight loss. So I'm actually hoping, Rob, to do a clinical trial sometime where we actually will, I'd like to prove like a scientist, I'm a physician scientist, I want to prove it. I'd like to see if, for example, people who are

Trying to get off of Zempik, if they convert over to, you know, a certain amount of allulose, can they help keep their weight down? Because right now, one of the big problems is as soon as you stop with Zempik, the weight comes raging back. And so it'd be nice to find a way to help people. But anyway, so that's kind of an interesting low calorie natural sugar that, you know, and I've gotten involved in it.

So for the sugar substitutes, then, to recap, sorbitol, saccharin have issues. And I guess we can cross off IHOP as a possible sponsor of the podcast going forward. And then some stevia and Splenda are sort of neutral in effects. But then this

This allulose, natural sugar, is better than neutral. It may have some beneficial effects as far as weight gain and glucose metabolism and these sorts of things. Does it have the same issues with urate and nitric oxide that fructose has, or those are avoided also? Yeah, it seems to be beneficial.

rather than detrimental. So fructose will inhibit nitric oxide. That's plays a role in why fructose raises blood pressure and allulose does not do that. And, you know, fructose raises uric acid and allulose does not do that. And in fact, we have some anecdotal studies suggest that it may lower uric acid, which needs to be pursued though.

Wow. Yeah, that's fascinating. Well, just about sugar substitutes in general, I often hear the comment that, you know,

no matter what their biological effects are, that there's this cephalic effect, you know, when we taste something sweet that our insulin raises anyway. And so anything that tastes sweet, even if it's completely benign, is that something significant or is that not a problem in your experience? Well, we looked at it. The only one that really does cause insulinemia is

is saccharin. And we can show that. That's the one that seems to be, that was the one that was reported in Nature journals. And we also confirmed that. The other ones don't do it so much. You know, they do stimulate dopamine. They all, when you eat something sweet,

it does cause this little pleasure response that may make you, encourages you to find more sweet foods. So it may not curb your craving for sugar. But interestingly, if you knock out the taste receptor, which we did this, so if you knock out the taste for sweet, animals will no longer like the low-calorie sugars.

but they still like fructose. And the reason is because fructose drives the craving response independently of taste. And that's how scary it is because, you know, if you can add sugar to foods like fructose at a level where you can barely detect the taste of

it's still going to make the food taste better because it creates that dopamine response, even though you can't taste the sweet. So it's a, it's a subtle. And so, yeah, it's fructose is, is definitely more powerful and glue, you know, sugar is more powerful than,

uh, at stimulating craving than the artificial sugars, but the artificial sugars still stimulate a little bit of dopamine. They do make you pick and choose sweet foods, uh, cause it gives you this little bit of a pleasure response. So that's, that's the negative side. Um, but on the other hand, if you said to yourself, well,

It's all what's wrong with eating sweet foods if the sugars are neutral or make me feel actually improve my metabolic health. So, you know, we have to start thinking a little bit differently as we make progress with some of these foods.

Yeah, well, thank you. It's such a minefield out there of information, but I like the ideas with allulose. I'm definitely going to check that out. That's great. Great information and good luck with your new ventures there. Richard, how can people follow you on social media and find out more about your work? Yeah, I have a website. It's pretty active called drrichardjohnson.com.

Check that out. And, you know, I do do Instagram more than I do the other social media venues. But my Instagram is Dr. Richard J. Johnson. And, you know, check me out. My book is available through lots of sites and pretty much all the book vendors. So, yeah.

- Well, thanks so much, Richard, for spending this time with us. It was fascinating. It certainly opened up my eyes on this important area that each of us face every single day with every meal. - And good luck to you too, Rob. I'm looking forward to seeing your book. I know it's coming out in June and I'm really excited about that.

Oh, well, thanks for the plug. Well, anyway, Richard, it's been wonderful. And thanks for this. And also thanks for all the great work you're doing and everything. Yeah, and same to you, Michael. If you're enjoying this program, please hit that subscribe button or even better, leave a review. Your support makes it possible for us to create the quality programming that we're continually striving for.

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