Dr. Tim Harlan and Dr. Rob Lustig discuss the harms of ultra-processed food, what makes a food healthy, and the food industry’s future.

It’s more important to understand what a nutritional label says, what is valuable, and what ingredients could be leading to metabolic dysfunction. The more of a foundation people have for understanding these labels, the more they’ll be able to take their health into their own hands.

In the words of Dr. Rob Lustig, eat real food. That is the key. Dr. Lustig is an advisor to and friend of Levels. He’s the author of many books, a mentor, a researcher, and somebody we all look up to. 

He sat down with Tim Harlan, a professor of medicine at George Washington University School of Medicine. Dr. Harlan, an author and a chef, launched a site called drgourmet.com, where he aggregates all of his work.

Why What’s Done to Food Matters

Rob Lustig: I’m sitting with my colleague, guest, friend, and confidant, Dr. Tim Harlan. Tim has many, many attributes. He is an internist at George Washington University and the head of its culinary medicine group. He is also a bonafide chef. Most importantly, he is the best-dressed doctor in the world. Tim, welcome and thank you for everything, and thank you for doing this.

Tim Harlan: It is always fabulous to be with you, Rob, always.

Rob Lustig: Why don’t we get started with that chef tidbit? What got you to move from being a chef to being a doctor? What was that spark?

Tim Harlan: I grew up in the restaurant business. I started washing dishes when I was 12, back when you could do that with permission from your parents and school. I think my mother figured she knew where I was going to be on Friday nights if I was working. I worked in the restaurant business throughout my teenage years and into adulthood. I managed my first restaurant at 18. I owned a little French bistro. I was a chef-owner at 22. I closed that restaurant, in part to go to college, and with the idea that I’d get a hotel and restaurant management degree. 

One thing led to another. I took a wrong turn one day and ended up in medical school. Part of the reason I ended up in med school was because my wife at the time had Type 1 diabetes. As a pediatrician, you know the challenges, especially having grown up in the sixties when diabetes care was much different. The technology was very challenging. She had some health problems, and I had begun to adapt what I did. I was approached by a publishing group in Atlanta to create some patient education materials. I wrote my first book about food while I was in medical school, called It’s Heartly Fare. It’s kind of a food manual for patients with cardiovascular disease. 

I have been standing at the intersection of food and health for 35 years now, since that book was published. Until recently, it was a very lonely corner. Trying to help make changes in how we eat and showing people how to eat great food that just happens to be great for you has been challenging. But the last 10 years have been revelatory. A lot of the work we’ve been able to do together wouldn’t have been possible 20 years ago.

Rob Lustig: Indeed. It’s like the sky opened up, and all of a sudden, everybody’s interested in food. It used to be they were only interested in food for taste, and now they’re interested in food for health, for the environment, for climate, for economics. Food has sort of taken its place on the proverbial humanitarian plate. One of the reasons is because we realize we have to feed 10 billion people by the year 2050, and we’re not going to have the land and the ocean to do it. This has generated a distinct concern around the world: What are we going to do, especially as climate change gets worse and we are going to need four central valleys of California when we won’t even have one?

Tim Harlan: I would posit that we’ve always cared about taste and flavor, and to a great extent, health. We’ve had long discussions about this over the course of the last few years, and about how the food industry has changed, in many ways in an effort to address exactly what you’re talking about: getting food to more people. 

Malnutrition used to be the problem. People couldn’t get enough quality food, and that expansion unfortunately led to ultra-processed food, which ends up being harmful. Food is our universal experience. It’s our shared experience. We all eat. We have to eat to fuel, but we also eat for pleasure and for socialization, and to be with family and friends and because it’s comforting. The challenge is exactly what you say: How do we do that in a way that delivers the best quality and the best food—great food that just happens to be great for you—for our fellow citizens?

Rob Lustig: I totally agree. Food is our shared experience. Right now, our shared experience is dying early, and that’s the problem here. We have this thing hanging over us now, and I credit many of our physician colleagues and others with this new concept of food as medicine. Writing prescriptions for vegetables and getting it covered by insurance is a great idea. 

Food can be medicine, but it can also be poison. That’s what we’re seeing. The question you and I have now put to paper is, How do you figure out the difference? How do you tell what’s medicine and what’s poison? What do you do about it? That has launched us into the world of ultra-processed food. Why don’t you describe how we’ve come together, and what our joint project that led to today’s conversation is?

Tim Harlan: You and I have been connected for a while, and we have a shared ethos. Four years ago, you reached out to me about a project you were working on. It was a little mysterious at the time, but what came to light was that a Kuwaiti dairy company, called KDD, was interested in transforming their product line. One of the owners had dealt with some health issues and wanted to make certain he was delivering the best quality products in a region of the earth that is very challenged by diabetes and obesity and food-related illness.

You brought together a team, which I am part of. Some of the other members of that team include Andreas Kornstädt, a super fascinating computer scientist and information technologist who’s developed some terrific data-analytics software around food called Perfact; Wolfram Alderson, a food advocate and activist; as well as Rachel Gao, is a nutritionist and specialist in fatty acid research.

We all eat. We have to eat to fuel, but we also eat for pleasure and for socialization, and to be with family and friends and because it’s comforting. The challenge is exactly what you say: How do we do that in a way that delivers the best quality and the best food—great food that just happens to be great for you—for our fellow citizens?

You brought me to the table partly because I’m an internist and practice medicine every day, working with patients and seeing what the end result is, like you do. I’m also a chef and still develop a lot of recipes, as well as a lot of educational programming here at GW with the culinary medicine program, and with the advisory board at Culinary Medicine, the nonprofit I help lead. Culinary Medicine helps educate healthcare professionals, and now food-service professionals, about healthy eating and how to transform the conversations we’re having with our patients and our patrons around health and food. And you come to the table because you’re a genius.

Rob Lustig: I don’t know about that.

Tim Harlan: You’re just an all-around smart guy and a pediatric endocrinologist.

Rob Lustig: I’m a pediatric endocrinologist, and we’re a bunch of OCD data-driven guyse That, I’ll accept. The fact of the matter is we have a food problem. We all have a food problem, and that is because we switched our diet. We switched it for ostensibly rational reasons. But we basically abdicated our ancestral diet, which, for lack of a better word, we can call real food, which we used to have. 

For this new thing, we have technologically driven and mass-produced lots of flavor, lots of tastes called ultra-processed food. Our colleague in Brazil, Dr. Carlos Montero, who is a public-health epidemiologist, recognized it’s not what’s in the food that matters, it’s what’s been done to the food that matters. That’s the difference between real food and ultra-processed food: what’s been done to the food.

He developed a food-classification system called Nova, which doesn’t stand for anything. It means “new system” in Portuguese, but basically on the degree of processing. I like to demonstrate to students and other clinicians how the Nova system works. 

Let’s take an apple as an example. Nova Class I would be an apple picked from the tree. Nova Class II would be apple slices—destemmed, deseeded, possibly deskinned. Nova Class III would be applesauce—macerated, potentially cooked, possibly with sugar, and maybe even a preservative added. Nova Class IV would be a McDonald’s apple pie. Those are very different apples going into the McDonald’s apple pie. 

One of the reasons I wanted you on this scientific advisory team to advise KDD was because of all the steps that take you from that apple to that McDonald’s apple pie, and you knew what the interventions could be to be able to mitigate those risks.

Tim Harlan: Yeah. And the Nova Class IV, as a different example, would be the apple juice, which is basically Coca-Cola, in a way. The challenge is (and I think it’s changing) that our colleagues in medicine, and many of our patients and citizens in the community have, think all four of those—the apple, the peeled apple, the apple sauce, and the apple juice—are fruit. They’re not all fruit. They’re all fruit derived. 

As you go down the line, you basically, one step at a time, strip all of the goodness out of that beautiful, poor, innocent apple you started with. That happens with a lot of food. The more technical example might be a wheat berry. You can eat wheat berries whole, and they’re terrific in cereals. But with every step you take—stripping away the bran, separating the endosperm—you eventually get to just white flour, which is essentially sugar. They’re all wheat, right? Well, they’re all wheat products. But the further you get away from the goodness of that original ingredient, the more problematic it becomes. 

You and I both agree we have to do that to some extent, and we do that to some extent because we make bread, for instance. That’s going to be Nova II or maybe even Nova III, depending on the quality of the bread. We have to do that because that’s how we eat, but trying to do that in the safest way possible without a lot of other added ingredients. 

That’s where we come to the table with this scientific advisory team, investigating what else is being done to that recipe, not just the actual ingredient itself. But now you’re going to put those ingredients together in bread. What else are you doing in that bread with stabilizers, emulsifiers, different artificial ingredients, natural ingredients, et cetera? Oftentimes, for folks looking at the package, it’s just confusing. 

I have a friend who says, “I can make bread or baked products with six ingredient: water, flour, butter, maybe some fat, some sort of leveling agent, salt, and maybe a little bit of sweetener to activate the leavening agent, depending on what the leavening agent is.” But then you turn over that loaf of bread in the grocery store and it’s got 32 ingredients in it. Where did all those other ingredients come from?

Rob Lustig: I always tell people the best way to understand this is to take a look at a loaf of grocery-store bread versus a loaf of bakery bread. I say, “How quickly does each one get stale?” The bakery bread will be stale in two days. The grocery store-bread will be stale in about three weeks. What’s the difference? They’re both bread. How come the bakery bread gets stale so quickly? The answer is, they added sugar to the grocery bread. 

Why did they add sugar to the grocery bread? Because the sugar doesn’t boil off when they put it in the oven at 450 degrees. The sugar stays put, and the sugar holds on to water. It’s hygroscopic, in the same way we put little grains of rice in our salt in an attempt to keep the salt from caking. The grain of rice acts as a desiccant.

The sugar they add to the bread holds on to water. It’s called water activity. It keeps the bread from getting stale for a much longer period of time. That process alone reduced the health value of that bread. In addition, they took the fiber out of the bread. 

I learned something that just floored me, from the guy who runs the bread lab at Washington State. His name’s Doug Jones. I actually learned it at your conference, in New Orleans back in 2019. 25 to 30% of the weight of a wheat kernel is the husk, the bran. That’s a lot. I had absolutely no idea it was 25 to 30% of the weight. 

That means that if something is whole-grain bread, because the husk is the fiber, the carbohydrate-to-fiber ratio should be about three to one. I dare you to find a bread anywhere in any grocery store that has a carbohydrate-to-fiber ratio of three to one. It’s almost impossible. There are a couple. They’re rare. They’re like German fitness bread. They’re very dense, and basically non-glutinous because the husk is still intact; the gluten is still inside the kernel. They make a lousy sandwich because there’s no fluffiness to them. They’re very crumbly, and heavy as a brick. If you threw it at somebody’s head, you could knock them out. That’s whole-grain bread. Everything else is a joke.

Tim Harlan: But at the same time, perfection is the enemy of success, and we want to eat great food that is culturally and socially comfortable to us. You can get the three-to-one or four-to-one carb-to-fiber ratio fairly easily, but it takes a little bit of work. 

The other challenge is it’s not just that we’ve taken out that bran and stripped out all that goodness—and in the process a lot of the flavor, too—but for industrially produced bread, the squishy white bread you get off the shelf, there are ingredients put in there for a lot of different reasons.

One of them, for instance, is DATEM, diacetyl tartaric acid esters of monoglycerides. There’s not a lot of DATEM in the bread. Those monoglycerides have sort of been glommed onto some other organic acids, and it basically helps improve the yield of that flour. 

In the bakery around the corner that’s making that nice, fresh sourdough, with, let’s say, a pound of flour, they make four, five, maybe six big loaves of bread. With a pound of flour using DATEM, you can make double that amount. That’s why it’s so squishy, because, like you said, it’s got a lot of air in it. The sugar helps trap the moisture. 

But there are these other ingredients, these emulsifiers and such we’ve looked at, that may be pretty harmful to the body, starting with the lining of the gut, and then moving onward from there to the liver, and potentially the rest of the bloodstream in the brain.

Rob Lustig: Indeed. We learned, from the work of the Elinav Lab at the Weizmann Institute in Rehovot, Israel, that these emulsifiers are used in virtually all ultra-processed food in some fashion: carboxymethyl cellulose, polysorbate 80, carrageenan. These are all emulsifiers. 

What are emulsifiers? Think about it. They are detergents. One end is polar, and the other end is nonpolar. That’s very specifically so that the fat and the water can be dissolved together, because either the fat will bind to the nonpolar end or the water will bind to the polar end. That’s how you lift out a stain. That’s basically what Tide is. Tide is an emulsifier. It’s a detergent. 

What happens to your gut if you swallow a detergent? The detergent will eat the mucin layer right off your intestinal epithelial cell, exposing that intestinal epithelial cell to the sewer that is your gut microbiome. Now you’ve got irritable bowel syndrome, potentially inflammatory bowel disease, and the phenomenon we now commonly refer to as leaky gut, which leads to an inflammatory response, and also ultimately a metabolic response.

The Metabolic Matrix: 3 Keys to Metabolic Health

Rob Lustig: This rubric of what’s in the food is not important. It’s what the food does to you that is important. This is how we ultimately came together in this KDD program to develop our principles of health. 

What makes a food healthy? We came up with three principles we could all agree on that fit the literature. I want to delve into those three with you. Number one, protect the liver. Number two, feed the gut. Number three, support the brain. Can you tell us how the liver gets protected, and I’ll pick up from there?

Tim Harlan: Part of the first step for protecting the liver is to support and feed the gut really well. Folks hear a lot about eating probiotics or prebiotics, et cetera, but what does that actually mean? It means delivering as high-quality, natural food as possible, and eating high-fiber food that supports the gut and protects it. 

The second step of that is adding those prebiotics of the fiber, and then probiotics of other quality fermented foods, which help support the gut microbiome. We want to deliver really great quality, and as whole and natural a food as possible—something as close to the source as possible.

The next step in feeding the gut properly, so you are protecting the liver, is to make certain that a lot of these added ingredients we were talking about—the emulsifiers, monoglycerides, et cetera—are out of diet and out of ultra-processed food. We agree it is possible; there are alternatives. It might cost a little bit more, and it will require some retooling and rethinking and innovation, but it is absolutely possible. 

To recap, step number one: feed the gut, and feed it really well, because in that gut, three things happen. The first thing is digestion. We break up the food. The second thing is absorption. We’re absorbing food mostly across the lining of our small intestine. The third thing is the metabolism of that food. That metabolism primarily begins at the liver. 

After we’ve fed the gut properly, how are we going to protect the liver?

Rob Lustig: The liver’s where the action is, because it is where metabolism meets inflammation. If you protect the liver, you keep your insulin down. If you keep your insulin down, the metabolic processes that drive all of those horrible diseases of metabolic syndrome—Type 2 diabetes, hypertension, dyslipidemia, cardiovascular disease, cancerdementiafatty liver diseasepolycystic ovarian disease—will be ameliorated. 

You’ve got to get the insulin down. In order to get the insulin down, you’ve got to keep your liver healthy. How do you do that? Don’t give it the substrate that makes it sick: sugar. Prior to 2013, the substrate that made it the sickest was trans fats. We learned, as early as 1957, that trans fats were poison. It took the FDA until 1988 to resurrect that information. The NIH started funding studies to look at the role of trans fats in chronic disease. By 2006, the FDA had added trans fats as a line item on the nutrition-facts label. By 2013, they were deemed poison. They were removed from the “generally recognized as safe” list, and now they are banned in our food supply. 

Having said that, there are ways you can make your own trans fats at home, like burning olive oil. That’ll make a trans fat. It’s not like they’re completely gone, but at least the food industry is not using them at industrial doses. Now that the trans fats are gone, sugar is the most egregious toxin to the liver.

If you protect the liver, you keep your insulin down. If you keep your insulin down, the metabolic processes that drive all of those horrible diseases of metabolic syndrome—Type 2 diabetes, hypertension, dyslipidemia, cardiovascular disease, cancerdementiafatty liver diseasepolycystic ovarian disease—will be ameliorated. 

Why is that? Sugar is “natural.” Sugar is celebratory. Sugar is apple pie and 4th of July, and your grandmother basically pushes it on you every time she sees you. How can sugar be a toxin? Well, there are two molecules in sugar: glucose and fructose. The glucose is not a toxin. The glucose is what every cell in the body uses for energy. Glucose is so important that if you don’t consume it, your body makes it. That’s how important glucose is. 

But that other molecule, fructose, the sweet molecule, is the molecule that makes sugar pleasurable. Glucose isn’t all that pleasurable, and you don’t see people going around chugging Karo syrup. That’s glucose. Fructose is the molecule that makes sugar worth the experience. Well, it turns out fructose is addictive. It actually goes to your brain, and activates the reward center in the same way nicotine, cocaine, and heroin do.

It is extremely addictive, and we have sugar addicts. This is a major problem. But the food industry knows sugar is addictive and that’s why they put it in. The problem is what that fructose does to your liver: it is not able to be metabolized to completion. The mitochondria get sick. There’s an enzyme in mitochondria called AMP kinase. Fructose inactivates that enzyme directly, thus reducing your mitochondrial function, reducing your ATP generation, reducing the energy availability within your cells, which make them sick, and then they start dying. Fructose is a dose-dependent chronic mitochondrial and liver toxin. There’s no medicine for that. The only thing you can do is to reduce the substrate, and therefore reduce the availability of that molecule. 

Protect the liver from things that make it sick, like fructose. There are other things, too. Protect it from cadmium, which is an oxidative stress to the liver. Protect it from, like you said, emulsifiers, and possibly even artificial sweeteners, like sucralose and aspartame, that have hepatic effects. Keeping your liver in top flight condition is tantamount to promoting metabolic health, and it’s from our food. 

That then leads us to the third precept of our metabolic matrix: protect the liver, feed the gut, support the brain. 

Why don’t you tell people why omega-3s are so important?

Tim Harlan: Supporting the brain is actually one of the easier of all of these, because we’re talking about really changing the equation in what are known as essential fatty acids. There are some fats we need because our body can’t make them on its own, specifically omega-6 and omega-3 fatty acids. 

The omega-6 and omega-3 has to do with how the particular molecule of fat is configured. They’re similar to each other, but very different. We need both. We need to consume both in a ratio of about four to one, omega-6 to omega-3. We need a little more omega-6, but we need the omega-3s as well.

There are some challenges here. One is that in our food supply, a lot of the poor innocent oils get corrupted through hydrogenation, where they are bubbled and changed. But they also are corrupted because a lot of those oils and fats high in omega-6 are cheaper. They also work a bit differently with their viscosity and how they act in food and baking. But mostly, they’re less expensive. Consequently, they are used in a very high ratio in processed and ultra-processed food in Western society, and now all across the world. 

The ratio that we’re getting here in America is probably somewhere between about 16 to one, omega-6 to omega-3, maybe as high as 20 to one omega-6 to omega-3, or even higher. There’s a lot of beating the drum about eating more fish and more nuts and more avocados, the things that are higher in omega-3 fatty acids. Olive oil is one of those prototypical plant-based oils that’s high in omega-3 fatty acids.

Trying to get more omega-3s is part of the equation. We don’t get enough in our diet, partly because we don’t get enough as a result of the ratio, and partly because they’re not as available to us. It’s about trying to change that equation in how processed and ultra-processed food is created, and making certain that ratio of omega-6 to omega-3 fatty acids is flipped, and really trying to bring it back down to normal. 

The challenge for this, without spending another hour doing a physiology lecture, is how those fatty acids are utilized, especially by the brain, and how they’re utilized by other parts of the body in the bloodstream. The pro-inflammatory impact of omega-6 versus the anti-inflammatory impact of omega-3 is a problem for atherosclerosis, or hardening of the arteries, heart disease leading to heart disease, stroke, et cetera.

The real thing we think is critically important is protecting the brain by changing that ratio, reducing the footprint of omega-6 and increasing the footprint of omega-3 fatty acids in the food supply. That’s pretty easy to do if you’re cooking all of your own food and you’re using olive oil and higher quality oils and fats—lots of nuts and seeds, more seafood, but less seafood than you think, and less land animal protein. It will help get that ratio closer to normal. 

But not everybody has the ability, time, or distribution we need in order to get food into folks’ hands. We need to process food. We need to make recipes and meals and breads and other pastas, et cetera, but we can do that in a sensible way that feeds the gut and protects the liver and supports the brain.

The real crux of that, for supporting the brain, is improving the essential fatty acid ratio. But there are a lot of other things that went into our discussion of supporting the brain, like making sure we’re not delivering other harmful chemicals to the brain—cadmium, mercury, other heavy metals—which can be in our food supply.

How Working with Kuwaiti Danish Dairy Provided Insight on the Modern Food Industry 

Rob Lustig: Once we came up with our rubric, what we now call the metabolic matrix, the question was, How can you apply it to an ultra-processed food portfolio? How do you turn ultra-processed food into healthy food? Is it possible? That was the charge KDD levied to us, which we took on. It basically took us two years to figure out. 

What were the necessary steps? The first thing we had to do was actually figure out what was in the food to start with. KDD has a 180-item portfolio. Where did they get their ingredients from? Did they grow them? It’s Kuwait. It’s hot. There are no animals. They would die.

They make yogurt, they make flavored milks, they make ice cream. Well, where do they get their milk from? They get it from milk powder from New Zealand. Now, did they know what was in the milk powder from New Zealand? Not a clue, but we needed to know, because we couldn’t just accept the fact that this milk powder came from New Zealand and was perfectly fine and healthy. Who knows what they were feeding those sheep or cows or whatever else? 

The bottom line was we had to do an exhaustive biochemical analysis of virtually every single ingredient KDD used, since all of them had been processed. All of them had come in on ships from somewhere else because there’s no real food in the Middle East because of the heat, because of the climate.

Fructose is a dose-dependent chronic mitochondrial and liver toxin. There’s no medicine for that.

We sent all of these ingredients to a biochemical analysis center in Des Moines, Iowa called Eurofins. We figured out what was in all the food and made recommendations to KDD as to whether or not those vendors were actually selling what they said they were, whether they were including things that maybe they shouldn’t, and whether or not they needed to find other vendors. 

This created a fair amount of political turmoil within the company, and also between KDD and its vendors. You have to have a company willing to put in the work and willing to take it on the chin if necessary in order to be able to do this. We found many things in the raw materials that were being shipped to Kuwait that needed to be rethought, replaced, refurbished, re-engineered, and reused. That was the first step of the KDD innovative experience.

Tim Harlan: The second step is ongoing, as they now slowly but surely are beginning to redo those recipes for their products. And again, this is food at an industrial scale. While we all want food to be as local as possible, the practicality of that and making certain we’re feeding ourselves is very challenging in what is a mostly urbanized world—and also in those areas that are not urbanized and have food challenges for a host of different reasons. Processed food does not necessarily need to go away. It just needs to be rethought.

How do you take a product like ice cream and make it satisfying, delicious, and creamy, with the right chocolatey flavor, while ensuring you’re reducing the emulsifiers and the sugar footprint by using other non-nutritive sweeteners? How do we make sure you’re using better quality fats wherever possible? Or using chocolate—many sources of chocolate have very high levels of cadmium—that’s safer while ensuring we’re improving that chain of command? How do we make sure there’s integrity in the products being delivered? It’s a tall order. 

Our team has every respect for the idea of a multinational like KDD, or Pepsi or Nabisco. These are challenging positions for large multinational companies to be in. But they are doable, and they’re important. It’s a moral responsibility for these companies and their executives to make certain they are delivering the best quality, least harmful food to their patrons. 

It’s going to take some time to turn around the ship that has been steaming along very carefully and placidly for a little over a hundred years, since Kellogg’s invented the cornflake. Can we have better quality cornflakes which taste fabulous and which we enjoy just as much, if not more, with less harmful ingredients and less sugar, less sodium, and better quality oils and fats? Absolutely. It’s entirely possible. Is it hard work? Yeah, it’s a heavy lift, but it’s a lift worth doing for society. 

There’s another piece of this puzzle we also thought was important for KDD and other multinationals, which is the integrity of other pieces of the supply chain: packaging, sustainability for products, impact on the environment. As you said, there’s a lot that goes into this. There’s a lot we have to think about in how we’re going to feed ourselves in the next 25 to 30 years, but those are doable. 

Our colleagues at the multinational food companies have the ability, and they have the money. They really do. I understand the concept of putting shareholders first, but those shareholders are also your patrons, and harming your shareholders is a double-edged sword. You might be benefiting your pocketbook, but are you harming their health? That’s a really important moral and ethical decision that has to be undertaken by our colleagues in the food industry.

Rob Lustig: My concern is harming our children, because they are the future. Remember, children are the canaries in the coal mine. Whatever it is that we get sick with, they get sick with worse, which of course is why children now have the diseases of aging when they’re five years old: Type 2 diabetes, fatty liver disease. We’re even seeing cognitive decline in five-year-olds because of the food supply. 

You’re right. Poisoning your population is not a growth strategy. This is what they said about tobacco: do not poison your consumers, but that’s what we’re doing now. I have absolutely nothing against people making money, but they’ve got to make money doing the right thing, not the wrong thing. That’s where tobacco went off the rails. I’m worried the food industry is doing the same thing. They’re making money doing the wrong thing.

But they can make money doing the right thing. Does it mean a change in what they’re doing? Absolutely. The question is, How do they do that? What’s the roadmap for being able to do that? That’s basically what we did in this paper that just got published in Frontiers in Nutrition called “The Metabolic Matrix.” 

An example of what we did: sweeteners. There’s something wrong with every sweetener. Obviously there’s something wrong with sugar. We just discussed how fructose interferes with AMP kinase and mitochondrial function. There’s something wrong with all the other sweeteners, too. There’s something wrong with sucralose. It causes alterations in the microbiome and causes leaky gut.

There’s something wrong with aspartame. It gets turned into toxic byproducts, which have actually been associated with cancer, and possibly dementia as well. There’s something wrong with monk fruit because it still generates an insulin response and still drives chronic metabolic disease. There’s something wrong with Stevia for the same reason. 

The question is, How do you sweeten a product and still have people who want to consume it and yet still make it healthy? This was perhaps our biggest challenge in this exercise with KDD. They’re making a lot of sweet things. 

The first thing we learned was that if you look at all the different “no-sugar-added” items on the market today, no one ever buys them a second time. They’re sweet, but they’re not very interesting. There’s a big difference between being sweet and being interesting, and being interesting enough to come back a second time.

Tim Harlan: I don’t know, Rob, I think you’re sweet and you’re interesting.

Rob Lustig: Well, thank you. We learned you actually have to provide that reward signal. The non-nutritive sweeteners don’t provide that reward signal. That’s been shown on functional MRI. We determined what the upper limit of sugar availability in any given food should be in order to both be saleable, palatable, and, at the same time, not trigger a hepatic insulin-resistant response. 

We came up with one teaspoon per serving. One teaspoon is still rewarding, but not enough to, say, sweeten an ice cream. We had to then look at the possibility of a sugar extender. And what we came up with, and it actually looks like there’s some metabolic benefit to it, is a new sugar. It’s a naturally occurring sugar. It occurs in strawberries, it occurs in mangoes. Nature made it, and it’s called allulose.

There are a lot of products with allulose out on the market today. It is about 12 times as expensive as sugar right now, which is why you don’t see it very much. But when you look at the biochemical profile of allulose, it looks relatively benign, and it might, in some cases, even be beneficial. It lowers LDL, raises HDL, and might improve cardiovascular parameters. 

We clearly need more data to be absolutely sure of this, but no one’s found the problem with it. It is also an epimer of fructose, which means it’s very, very similar to fructose and binds to the same receptors. 

We found we could use allulose as a sugar extender, and that is what we’re proposing to KDD as an option. However, we found that there’s a political consideration. The Gulf Cooperation Council, which determines what gets into the country, hasn’t yet approved, even though the European Food Safety Authority has, and even though the FDA has. We’re working the political minefield in the Middle East as well, and working on the various political structures in the country to try to make this happen.

This has been a real revelation in terms of how one brings a food to market, and I’ve learned a tremendous amount during this exercise. I think we’ve done something really worthwhile and good.

Hope for the Future of Food

Tim Harlan: It’s been really fascinating and interesting. The very cool thing, from my end, is this is now bleeding into how we are educating healthcare professionals, as well as food-service professionals in the culinary medicine program that’s currently used across the country, at about 65 academic medical centers. These centers are teaching their medical students to cook, teaching their nursing students to cook, teaching their faculty to cook in a way that helps them understand food better. They can then change the conversation with their patients. 

We’re doing the same thing now with culinary schools, helping them train future food-service professionals and chefs, many of whom will often end up in the larger food-packaging industry. How do we help them understand making the healthiest possible food? 

When I’m talking with patients who are drinking sugar-sweetened beverages—that 16-ounce can of soda is going to have somewhere around 14 to 16 teaspoons of sugar, most of which is fructose—I often say, “Do you like iced tea?” Almost all of us really like iced tea. It’s kind of an American cultural thing. “Go home, pour yourself a 16-ounce glass of iced tea, put some ice in it, and then try to get 16 teaspoons of sugar to dissolve.” 

You can’t even get it to dissolve. The problem is that there’s just too much sugar in that sugar-sweetened beverage, where it probably only needs one teaspoon for every cup to cup-and-a-half serving for most of us. There is a way forward. It’s just about making certain that the food is not being manipulated in a way that, as Dr. Lustig said, helps reinforce our desire for that food. It’s doable, but it’s a heavy lift. It’s a big challenge.

Rob Lustig: Without question. When I went to medical school, I didn’t learn anything about nutrition. And my best guess is you didn’t either, not in medical school. You learned it elsewhere. 

In fact, one study looking at a little over 100 United States medical schools found that only 27% of the schools that answered the relevant survey questions met the minimum requirements set by the National Academy of Sciences. Among those schools, the number of contact hours for nutrition was only 19.6. When you think about medical schools being 6,000 contact hours of training, 19.6—which is like 0.003% to solve 75% of the pathologies we are taking care of—seems a little lopsided. 

In fact, your doctor doesn’t know anything about nutrition because medical school never thought that was part of the important curricula. They figured that was for somebody else to do. But it is for us to do, and we need to understand that food is medicine, but it can also be poison.

And it’s not about calories. It never was. Yes, we needed to feed a destitute population. Yes, we had problems with malnutrition and marasmus in the past. But that’s not what we have today. What we have today is metabolic disease due to food that is poison. We have to understand, as doctors and scientists, how to mitigate that and how to teach our patients how to mitigate that. 

We need to understand that food is medicine, but it can also be poison.

That is how I think of the work we have done together to create this rubric: Protect the liver, feed the gut, support the brain. Any food that does all three is, by definition, healthy. Any food that does none of those three is, by definition, poison. And any food that does one or two, but not all three, is somewhere in between. We need to look at food in that light. When we do that, we will start saying no to the processed-food industry. Then they will get the message, and then they will fix it. 

Years ago I met with an executive from a famous food company which will remain nameless for the moment, as will the name of the gentleman. He told me straight up, “We can change. We’ve changed before. We had to change back in the seventies when we went low-fat. We can change again with two provisos. We won’t go it alone and we can’t lose money.” 

10 years ago, both of those were non-starters. Today, we now have the roadmap for the entire food industry to be able to change, and the proof that you don’t have to lose money. In fact, you will make money. I’m hoping the work that we’ve done together, the work that we’re promoting, will ultimately be the signal—the sentinel to the food industry—that it’s time to get on board and fix the problem.

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