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Artificial sweetener could harm your gut and the microbes that live there – new study

An artificial sweetener called neotame can cause significant harm to the gut, my colleagues and I discovered. It does this harm in two ways. One, by breaking down the layer of cells that line the intestine. And, two, by causing previously healthy gut bacteria to become diseased, resulting in them invading the gut wall.

The study, published in the journal Frontiers in Nutrition, is the first to show this double-hit negative effect of neotame on the gut, resulting in damage similar to that seen in inflammatory bowel disease and sepsis.

To reduce childhood obesity, six years ago this month, the UK government introduced a soft drinks industry levy. This “sugar tax” required a levy to be paid for any soft drink – equivalent to manufacturers adding 72p for a three-litre bottle of soft drink.

Since the levy was introduced, there has been a nearly 50% decrease in the average sugar content of soft drinks. While reducing sugar content certainly addresses childhood obesity, it does not give the same sweet taste perception that consumers are used to experiencing in their diet. That’s where artificial sweeteners can make a real difference.

A supermarket aisle selling soft drinks.
The sugar content of soft drinks has been reduced by nearly 50% since the UK introduced the sugar tax. Matthew Horwood / Alamy Stock Photo

Artificial sweeteners are chemical compounds are up to 600 times sweeter than sugar with very few (if any) calories, and are cheap and easy for manufacturers to use.

Traditional artificial sweeteners, such as aspartame, sucralose and acesulfame potassium (acesulfame K) have been found in a wide range of foods and drinks for many years as a way to increase the sweet taste without adding significant calories or costs.

However, in the last few years, there has been controversy in the field. Several studies have suggested potential health harms associated with consuming these sweeteners, ranging from gastrointestinal disease to dementia.

Although none of these harms have been proved, it has paved the way for new sweeteners to be developed to try to avoid any possible health issues. These next-generation sweeteners are up to 13,000 times sweeter than sugar, have no calories and no aftertaste (a common complaint with traditional sweeteners). An example of this new type of sweetener is neotame.

Neotame was developed as an alternative to aspartame with the aim of being a more stable and sweet version of the traditional sweetener. It is very stable at high temperatures, which means it is a good additive to use in baked goods. It is also used in soft drinks and chewing gum.

Neotame has been approved for use in more than 35 countries, including the UK, although the European Food Safety Agency is currently reviewing the sweetener as part of a series of evidence‐based risk assessments of certain sweeteners.

While neotame has been shown to change the profile of gut bacteria, very little research has investigated the effect of neotame at the cellular level.

Kills the cells that line the gut wall

The new study my colleagues and I conducted aimed to fill that gap in our knowledge. We used a cell model of the human intestine and model bacteria from the human gut microbiota to study how neotame consumed in the diet could affect gut health.

We found that, at higher concentrations, neotame can kill the cells that line the gut wall and, at lower concentrations, the sweetener can cause the gut to become more susceptible to leaks. Both these effects could result in inflammation of the intestine, which is linked to inflammatory bowel disease and sepsis.

We found that exposure of human gut cells to the acceptable daily intake, as decided by food safety agencies, of neotame causes cells to die. However, it is worth noting that, because neotame is so intensely sweet, it is unlikely that a person would consume enough sweetener in their daily diet to achieve this amount.

At lower concentrations of neotame, which could be seen in the diet, we still found a breakdown of the gut barrier was sufficient to be associated with an increased chance of infection in the body.

In the gut bacteria models, a type of E coli and E faecalis, neotame did not kill the bacteria but instead increased their ability to form “biofilms”. When bacteria form a biofilm, they cluster together as a protective mechanism which makes them more resistant to antibiotics. Our study also shows that neotame increases the ability of the E coli to invade and kill human gut cells.

These findings are very similar to those with traditional sweeteners, such as sucralose and aspartame, in terms of their effect on gut bacteria and human gut cells.

This suggests that the next-generation sweeteners may not be the solution that had been hoped for. So we are still stuck with the vexing question: how do we enjoy a sweet taste in our diet without the health harms that sugars, and now sweeteners, seem to give?

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