Diet Foods Make You Fat: Research Shows Artificial Sweeteners Can Trigger Illness, Diabetes And Obesity

artificial sweetener roadsign image

Diet foods and drinks can cause illness, diabetes and obesity, according to major new research published tomorrow (Thursday 18 September 2014) in the leading science journal Nature.

Experiments on mice and humans have shown that artificial sweeteners change the make-up and behaviour of bacteria in the gut resulting in raised blood sugar levels. This is a key factor in the development of type 2 diabetes and metabolic illness linked to obesity. While an imbalance in gut bacteria – known as dysbiosis – is related to many intestinal disorders.

The research will come as unwelcome news to the global food industry. The diet food and drink sector in the UK is an enormously lucrative market worth around £1.6bn last year, according to market research firm Mintel. Indeed, the worldwide artificial sweetener market alone is estimated at between $2bn and $6bn, according to industry sources, suggesting that the total value of global sales of foods and beverages containing artificial sweeteners is many times that number.

Make no mistake about it: these findings will cause many people to reassess what they eat and drink and this will threaten to undermine the whole of the enormously lucrative diet food market. So it is reassuring to see the lengths that the research team have gone to in order to validate their findings.

Clear Results

The scientists studied the effects of three widely used artificial sweeteners: saccharin, sucralose and aspartame. They added supplements containing these artificial sweeteners to the diets of mice. The results were clear: the research team found that each of the three sweeten­ers altered the animals’ metabolism, raising blood glucose to significantly higher levels than those of sugar-consuming mice.

The researchers believed this was due to changes in the gut microbial make-up of the mice that they had observed. To check whether it was indeed these changes in gut bacteria that were actually responsible for the metabolic changes that they had seen in the mice, they gave the mice antibiotics to deplete the gut bacteria and they found that this treatment eliminated the glucose intolerance. Next they fed healthy mice with food contaminated with faeces containing the altered gut bacteria mixture from glucose intolerant mice – and sure, enough, the healthy mice developed glucose intolerance.

The scientists are in no doubt about what they have discovered. Eran Elinav, of the Weizmann Institute of Science in Israel, one of the authors of the Nature paper, bluntly told reporters during a telephone press conference on Tuesday (16 September 2014) that “sweetener exposure induced glucose intolerance” adding that “sweeteners induce microbial changes”.

The results of this research are clear: artificial sweeteners widely used in diet foods and drinks change the make up and function of gut bacteria and this in turn is responsible for the appearance of glucose intolerance.

Of Mice And Men…

Now, all this research in mice is strongly indicative but is not in itself proof of an effect in humans. So the researchers took seven healthy volunteers who did not normally consume artificial sweeteners and put them on a seven-day regimen of controlled high artificial sweetener intake. After only four days, half the individuals had elevated blood-glucose levels and exhibited an altered bacterial-community composition, mirroring the results that then research team had seen in the mice.

Next the scientists took faeces from these humans and gave them to germ-free mouse recipients that had never consumed artificial sweeteners and they saw that this then induced elevated blood-glucose levels in the mice. “Our results in humans are preliminary but do show the same link,” stated Elinav.

This research is dynamite. The results indicate that artificial sweetener consumption may contrib­ute to, rather than alleviate, obesity-related metabolic conditions, including diabetes by altering the compo­sition and function of bacterial populations in the gut.

Furthermore, there appears to be no upside in the use if artificial sweeteners. “In none of those experiments have we seen any beneficial effects of artificial sweeteners,” stated Eran Segal, of the Weizmann Institute of Science in Israel, another of the research team.

In their Nature paper, the scientists point out that the major changes in human nutrition including the increased consumption of non-calorific artificial sweeteners (NAS) have coincided with the dramatic increase in the obesity and diabetes epidemics. “Our findings suggest that NAS may have directly contributed to enhancing the exact epidemic that they themselves were intended to fight,” the authors state.

Segal said that this research should prompt a debate over the “massive use” of artificial sweeteners. Elinav was keen to stress that, in publishing their findings on artificial sweeteners, the scientists were not saying sugary foods are healthy or healthier than artificial sweetener containing foods. The scientists are not prepared to give any advice to consumers over the use of artificial sweeteners.

However, the practical implication of this research for many people will be that if you must have something sweet then go for the real thing, avoid the artificial stuff and consume all in moderation.

Better still: avoid sugar altogether and stick to fresh, natural and unprocessed foods.

Nature knows best.


This story is based on a research paper published in Nature and on a telephone press conference organised by Nature and held on Tuesday 16 September 2014


Artificial sweeteners induce glucose intolerance by altering the gut microbiota by Jotham Suez, Tal Korem, David Zeevi, Gili Zilberman-Schapira, Christoph A. Thaiss, Ori Maza, David Israeli, Niv Zmora, Shlomit Gilad, Adina Weinberger, Yael Kuperman, Alon Harmelin, Ilana Kolodkin-Gal, Hagit Shapiro, Zamir Halpern, Eran Segal & Eran Elinav published in Nature 18 September 2014 (Vol. 513, No. 7518) doi:10.1038/nature13793


Non-caloric artificial sweeteners (NAS) are among the most widely used food additives worldwide, regularly consumed by lean and obese individuals alike. NAS consumption is considered safe and beneficial owing to their low caloric content, yet supporting scientific data remain sparse and controversial. Here we demonstrate that consumption of commonly used NAS formulations drives the development of glucose intolerance through induction of compositional and functional alterations to the intestinal microbiota. These NAS-mediated deleterious metabolic effects are abrogated by antibiotic treatment, and are fully transferrable to germ-free mice upon faecal transplantation of microbiota configurations from NAS-consuming mice, or of microbiota anaerobically incubated in the presence of NAS. We identify NAS-altered microbial metabolic pathways that are linked to host susceptibility to metabolic disease, and demonstrate similar NAS-induced dysbiosis and glucose intolerance in healthy human subjects. Collectively, our results link NAS consumption, dysbiosis and metabolic abnormalities, thereby calling for a reassessment of massive NAS usage.

Read the abstract and get the paper from here.

Here is the text of Nature press release relating to this research:

Diet: Artificial sweeteners linked to abnormal glucose metabolism

Consumption of commonly used non-caloric artificial sweeteners may increase the risk of developing glucose intolerance (elevated blood sugar levels), a mouse and human study in Nature this week indicates. Mice fed on diets supplemented with sweeteners exhibit altered energy metabolism that seems to be modulated by the effects of sweeteners on the composition and function of gut microbes. Similar associations between sweetener consumption, microbial imbalances and impaired glucose metabolism are observed in humans.These results suggest that the use of non-caloric artificial sweeteners should be reassessed.

Non-caloric artificial sweeteners are widely used in foods and drinks, such as diet sodas and sugar-free desserts, and are recommended for weight loss and for treatment or prevention of metabolic disorders. However, data supporting the use of sweeteners arelimited, and studies have found both beneficial and detrimental effects of sweetener consumption.

Eran Elinav and colleagues show that mice whose drinking water was supplemented with glucose and a sweetener developed marked glucose intolerance compared with mice drinking water alone, or water with just sugar in it. The authors find that non-caloric artificial sweeteners exert this effect by altering the balance of gut microbes that have been linked to metabolic disease susceptibility. In addition, artificial sweeteners were found to alter the composition and function of the microbiome in a subset of humans. These microbial changes, in turn, contribute to glucose intolerance in these individuals.

These results indicate that non-caloric artificial sweeteners may exacerbate, rather than prevent, metabolic disorders such as glucose intolerance and diabetes.

Market data

Industry estimate of sweetener market size here and here.

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