ZOE Science & Nutrition - Recap: The truth about artificial sweeteners | Eran Elinav & Tim Spector

Episode Date: December 2, 2025

Today we’re diving into the world of artificial sweeteners. Back in July 1982, Coca-Cola launched a groundbreaking new product: Diet Coke. A healthier alternative for those Coke fans looking to cut back on sugar and manage their weight. Sounds great, right? Well, maybe not. You see Diet Coke, and many other low sugar drinks, rely on artificial sweeteners. And while they were once seen as a smart swap, emerging research is raising serious concerns about their long-term effect on our health. In this episode, I’m joined by Professor Eran Elinav and Professor Tim Spector to break down the latest science and explore how these sweeteners impact our gut microbiome. 🌱 Try our new plant based wholefood supplement - Daily30+ *Naturally high in copper which contributes to normal energy yielding metabolism and the normal function of the immune system 📚Books by our ZOE Scientists The Food For Life Cookbook Every Body Should Know This by Dr Federica Amati Food For Life by Prof. Tim Spector Ferment by Prof. Tim Spector Free resources from ZOE Live Healthier: Top 10 Tips From ZOE Science & Nutrition Gut Guide - For a Healthier Microbiome in Weeks  Better Breakfast Guide Have feedback or a topic you'd like us to cover? Let us know hereListen to the full episode here

Hello and welcome to Zoe Recap, where each week we find the best bits from one of our podcast episodes to help you improve your health. Today we're exploring artificial sweetness. Back in July 1982, Coca-Cola launched a groundbreaking new product, Diet Coke, a healthier alternative for those Coke fans looking to cut back on sugar and manage their weight. Sounds great, right? Well, maybe not. You see, Diet Coke and many other low-sugar, drinks rely on artificial sweeteners. And while they were once seen as a smart swap, emerging research is raising serious concerns about their long-term effect on our health.

In this episode, I'm joined by Professor Iran Ilenev and Professor Tim Specter to break down the latest science and explore how these sweeteners impact our gut microbiome. What is an artificial sweetener? Why did they exist? So artificial sweeteners, which

are currently... returmed non-nutrative sweeteners are a very diverse group of chemicals that feature a very intense sweet taste. In other words, they are much better than natural sugar in engaging and inducing taste receptors which lead to our brain interpreting their tastes as intensely sweet. So there are hundreds of times sweeter than the natural sugar. And these artificial compounds were developed and discovered over a century ago as means of satisfying people's sweet tooth without paying the caloric price. So I think the first of these compounds was saccharine, which was discovered over 100 years ago, and it was used as an inexpensive and intensely sweet

substitute to sugar. These compounds have been extensively integrated. into human diet with the hope and belief that we would generate this pleasurable, intense, sweet taste to many of our foods. So these compounds can be found both as an independent additives to coffee and so on and so forth, but also if you were to go to your local supermarket and look at the ingredient links of many foods, you would find these compounds integrated in many cases without explicitly, you know, telling the consumers that they're there. It's actually very hard and very difficult to,

it was one of our biggest challenges to find individuals who are not exposed to these compounds in their daily lives. And there's a huge range of them on there. So, I mean, as well as saccharin, which was the early ones, which came, I think, from the petroleum industry. A lot of these come from, you know, basic organic chemistry rather than as foods originally, discovered by accident. Then you've got the aspartames, the sucralosis,

the ACE-Ks, all the sugar alcohols, things like xylitol, also some newer ones, they're a monk fruit, neotame, there's an increasing list of these that are often used in combination now, even with sugar. So that's why it's very hard for, you know, people to work out what they're eating is because they're often mixed up now and very hard to separate them. Iran, I'd love to switch to your research now, you know, very Very few people are actually doing studies on the microbiome in human beings where they're able to really understand specific impact of specific foods. That's obviously something that is really fascinating to me and I think lots of listeners.

Could you tell us, you know, I think you're saying you started with this idea that these artificial sweeteners were inert. They didn't have any impact on us. What is your research shown? We started in exploring the possible impacts of these compounds, of these sweeteners. in animal models specifically in mice, which are very controlled settings that we can learn a lot from,

that they're not as complex as human beings and as diverse. My graduate student, now an independent researcher in his own right at Hopkins in the US, designed an initial experiment in which he gave high doses of some of these compounds into mice that have never, of course, seen these compounds. And to our astonishment, his results were that these mice were developing a higher tendency to develop disturbances in their blood sugar control.

They were kind of leaning towards the development of diabetes. He showed me these results. I did not believe them, of course, being a skeptic scientist, he repeated them again and again and again, and this was very, very reproducible. And this was the first eureka moment, which told us that some of the same. something in the body of these mammals, of these mice, was actually reacting to these seemingly inert compounds in ways which could be detrimental to health. And this started a very long journey in which we, at the beginning, mainly focused on one

of these compounds, which is called saccharine, it's the granddaddy of all artificial sweeteners. It's actually very popular as a sweetener in Israel, where we performed studies. and we really dove deep into this one compound tested it in different doses, including doses that are equivalent to the lower doses that humans consume, different mice, different genders, and so on and so forth. In all of these cases, we found that in mice housed in our facility

that carry a specific microbiome, the consumption of saccharine was associated with a quite remarkable tendency to develop disturbances in sugar control to develop diabetes. You're saying that you took these mice, you were just giving them this artificial sweetener. You weren't giving them any like sugar or doing anything

else that was changing their diet. You were just giving this artificial sweetener, which we've all been told, doesn't do anything on our body. A taste sweet that goes through. And in these mice, you actually ended up giving them diabetes, which is a disease that I associate with having lots and lots of sugar and other sweet

food. Is that right? Yeah, that's absolutely right. And this occurred when we gave these mice different diets, for example, a diet reminiscent of the Western diet full of fat or in healthier diets, and this seemed to be at least in our facility. And the question was, since this compound has been known and studied for a century, and we know that the mammalian cells, the mouse cells and the human cells probably don't digest it, how do the consumption of this compound result? in these a diabetic effect.

And this is where the microbiome came in. And we started looking into the microbiome because this is what we do in life. And we found to our surprise that the microbes were actually reacting to this compound. And we could even induce diabetes by taking the microbes from the guts of mice that were consuming saccharide

and transferring just the microbes into mice that have never seen saccharine. These recipient mice developed diabetes, proving that the microbiome was actually driving the effect. This was a very big eureka moment for us leading to the publication

of our findings in nature in 2014. And as you can imagine, this generated a lot of discussion that spanned outside of the scientific and medical communities. And one

must also mention that in this initial study, we've also also performed a very small preliminary study in human volunteers who were given saccharine, and we found that half the people who were exposed to saccharine didn't care at all. They didn't change their blood sugar control. Their blood sugar levels were completely the same. But the other half of these individuals developed marked disturbances in their blood sugar control,

even after a week of exposure to this compound. None of the individuals in this small preliminary trial actually improved the blood sugar control. This was a very counterintuitive, but a very important moment in this type of study because it told us something very fundamental, not only about artificial sweetness. It told us that rather than quantifying foods or food components in their ability to induce changes in the human body or in the mouse body in this case, we need to start thinking about how to quantify the recipient, the people who actually consume this compound.

And this goes against the one-size-fits-all dietary paradigm that was prevalent for 50 years before this and led to the personalized nutrition concept which was developed. And artificial sweeteners in our hands were the very first example of these personalized microbiome-driven effects. that dictate why one person would react to a given food, while the other person would not react to the same exact food, even when it's consumed at exactly the same quantities.

So imagine that you're saying that both Coca-Cola and our diet Coca-Cola is off the table, and same for all the other manufacturers. But there'll be a lot of people saying, well, it's really hard to switch from that to water, because I'm really used to all of these sweet tastes. Do you have like an easy tip for how to transition off those? drinks for anyone who's listening? Well, most of us have done this when we were kids.

I used to, I used to, anyway, have tea with about four spoons of sugar in it when I first started having it. And gradually, you just dial it down so that you can go to three and then to two and then to one. And I think the same is true with these products. You need to wean yourself off. I think that amount of sugar. And once you've done that, you know, I, you know, I, you know, I.

They're too sweet for me to actually have them now. We do have these thresholds for sweetness that we can manipulate ourselves and can be used to more bitter tastes and sour tastes and fermented drinks and things like this are an important way. So I think teas, kombuchas, and diluting down these products gradually to get yourself off them in a few months is probably the way to do it. I hope you found the information in this week's episode useful. If you're interested in improving your gut health, you might want to download our free

gut guide. It's packed with recipes and science-backed information to help you on your journey towards better health. Go to zoe.com slash gut guide to download it for free. Or if you're looking for another podcast to listen to, we have a lot more in our back catalogue. Would you like to know how to reduce your risk of dementia or how to make the most of coffee's hidden health benefits. Search for these episodes on your favourite podcast player.