The microorganisms in our stomach may be disrupted by some artificial sweeteners, which could increase the risk of weight gain, diabetes, and heart disease.Artificial sweeteners, which are typically not metabolised by the human body and can be hundreds to thousands of times sweeter than cane sugar, offer no or very few calories.


You recognise the emotion. You gulp down that diet Coke, enjoying the sweet flavour without worrying about the calories or guilt that come with sugar. But a recent study reveals that these artificial sweeteners might not be as risk-free as previously believed; in fact, they might even make people more likely to develop diabetes or gain weight.

Artificial sweeteners have long been associated with obesity in people, but this association had only been demonstrated in lab animals.Scientists in Israel have now tested these compounds on humans in a first-of-its-kind study. Their findings demonstrate that artificial sweeteners not only interfere with human gut microbes, which are crucial for supplying essential nutrients, producing vitamin K, and digesting dietary fibres among other things, but some may also slow the body's ability to remove sugar from the blood after a meal. The risk of developing diabetes, cardiovascular disease, and chronic kidney disease increases the longer glucose is in the blood.


Low-calorie sweeteners interfere with the function of gut microorganisms. Despite having very distinct chemical compositions, they have comparable impacts, claims Michael Goran, a professor of paediatrics and the programme director for nutrition and obesity at Children's Hospital Los Angeles

Eran Elinav, an immunologist at the Weizmann Institute of Science in Israel and the lead author of the most recent study, explains that they are utilised in the hope of providing us with the sweet flavour without making us fork over the calories. However, non-nutritive sweeteners are not harmless to anyone.

The intestine, nose, mouth, skin, and eyes all contain different types of bacteria, viruses, and fungi that exist naturally in and on human bodies.This enormous microbial community is made up of roughly the same number of cells as there are in the human body. This community, known as the microbiome, is seeded at birth and aids in digestion as well as immune system support and pathogen defence.

Non-nutritional sweeteners induce the alteration to the microbiome because some microorganisms use them as nutrients even though they have no or few calories for humans, leading to their proliferation. This leads to an imbalance in microbial populations, which can result in colon cancer or chronic intestinal inflammation.

Michael Goran, a professor of paediatrics and the programme director for Nutrition and Obesity at Children's Hospital Los Angeles, claims that while they are intended to be calorie-free for humans, they are not for our gut microorganisms, which may still flourish on them.

The Israeli study supports that non-nutritional sweeteners can modify the gut flora within two weeks of exposure and that individual differences may exist in how they affect sugar metabolism.

"It's a convincing study that demonstrates how artificial sweeteners actually impact the health of people. Even while they are different sorts of substances, they also have comparable impacts, according to Goran.

Nutritionist and the head of Yale University's Yale-Griffin Prevention Research Center, David Katz, concurs. This is an ingenious, complex, and convincing study that conclusively shows how non-nutritional sweeteners hinder glucose metabolism by specifically harming the microbiome.

Artificial sweeteners' sour past

Our intrinsic preference for sweet meals and aversion to bitter flavours are evolutionary adaptations that led humans to choose high-energy foods when nutrient-dense foods were in short supply. When natural sugars like glucose, fructose, cane, or milk sugars are digested, calories are produced that support the operation of our organs. Non-nutritional sweeteners, which can be hundreds to thousands of times sweeter than cane sugar, usually do not contain any or very few calories since they are not digested by the body.


At Johns Hopkins University, saccharin, the first commercially available non-nutritive sweetener, was inadvertently found in derivatives of coal tar. Saccharin avoided being outlawed by the fledgling United States because to President Theodore Roosevelt, who believed that this manufactured sugar was a guilt-free way to reduce weight. Drug Enforcement Agency. When the FDA attempted to outlaw saccharin once more in 1977 due to concerns that it might cause cancer in rats, Americans retaliated. They protested the proposed prohibition in countless letters to Congress, the FDA, and President Jimmy Carter.

In the end, all that was needed for saccharin-containing items was a cancer warning label. However, this was also abandoned in 2000 when researchers discovered that saccharin is metabolised differently in humans than in rats and does not increase the risk of cancer in people.

Thousands of beverages and foods around the world have low- or zero-calorie sugar alternatives, which produced $21.3 billion in revenue in 2021. As the demand for these sweeteners continues to grow, particularly in low- and middle-income nations, this number is anticipated to increase. According to a 2017 national nutritional study, more than half of adults and 80% of children in the United States regularly eat low-calorie sweeteners. Adults with obesity consumed more low-calorie sweeteners.

From mice to humans, artificial sweeteners

In order to develop microbiome-based tailored treatment, Elinav has been researching the relationships between diet, gut flora, and the risk of contracting prevalent diseases like obesity and diabetes for more than a decade.

In 2014, Elinav and colleagues discovered that the blood sugar levels of mice fed aspartame, sucralose, and saccharin were all noticeably higher than those of mice fed sugar.

When mice without their own gut bacteria and mice who had never been given artificial sweeteners were given gut germs from mice treated with artificial sweeteners, their blood-glucose levels spiked as though they were ingesting artificial sweeteners themselves.

According to Elinav, some of these artificial sweeteners are detected by mice and have an impact on the gut microorganisms, which are amazingly capable of metabolising a variety of these substances. He made the decision to investigate whether the same was true in humans and whether changed gut flora could affect how glucose is metabolised.

Elinav's team initially checked 1,375 volunteers to see if they regularly consumed any zero-calorie sweeteners. They chose 120 persons who had never been exposed before and administered one of the four widely used sweeteners—saccharin, sucralose, aspartame, or stevia—for two weeks to each of them. After then, the volunteers were observed for a third week. Researchers contrasted their blood glucose responses with those of individuals who did not receive artificial sweeteners.

The populations of gut flora among subjects showed substantial variations 14 days after starting any of the four tested artificial sweeteners. It appears that gut microorganisms react quickly to artificial sweeteners since "we detected very different changes in the composition and function of gut microbes, and the chemicals they secrete in blood," says Elinav.

Volunteers had their blood glucose levels checked after drinking a test glucose beverage to see how artificial sweeteners affected the body's capacity to handle the spikes in blood sugar that occur after eating foods that contain sugar. Blood glucose levels should typically reach their peak in 15 to 30 minutes and then return to normal in 2 to 3 hours. Glucose intolerance is a condition where the blood glucose levels remain elevated and indicate that the body isn't properly digesting and storing extra glucose.

Sucralose and saccharin in the Israeli study caused the body to become more susceptible to glucose intolerance, which, if it continues, can result in weight gain and diabetes. The glucose tolerance was unaffected by aspartame or stevia at the studied intake levels.

Elinav claims that the gut microbiome may have an impact on how pronounced the glycemic responses that are brought on by saccharin and sucralose are.

Researchers gave faecal bacteria from human participant participants' stool to germ-free mice to confirm that changes in microbial populations affected blood glucose levels. According to the study, mice's ability to regulate their blood sugar levels was reduced by microorganisms from volunteers with high blood sugar levels.

The four people who ingest non-nutritive sweeteners all have significantly altered gut microorganisms and the compounds they leak into our bloodstream, according to Elinav. "Each group gave a different response.

The study is the first to demonstrate how uniquely the human microbiome reacts to non-nutritive sweeteners, despite the fact that the volunteers weren't followed in the study for an extended period of time. Depending on their microbiota and the sugars they consume, this may affect some consumers, if not all. According to Goran, "this study is pretty thorough in terms of the microbiota."

However, argues Dylan Mackay, a human nutrition specialist and diabetic at the University of Manitoba in Canada, "this study raises more issues than it answers." According to Katz, it is unknown whether similar glucose dysregulation would be observed in those who regularly consume such sweets or whether there would be some degree of adaptation as participants were screened to be free of prior exposure to non-nutritional sweeteners. It is also not known if variations seen between people could be brought on by genetic, epigenetic, or behavioural factors.

Do we need to start consuming more sugar?

According to several researchers, alterations in the gut flora following a brief exposure to non-nutritional sweets do not warrant alarm. According to endocrinologist Karl Nadolsky of Michigan State University, "it is plausible to assume the diversity of non-nutritional carbohydrates to have some form of impact physiologically." But it's a very large leap to extrapolate it to clinical results and concerns.

According to Mackay, "We don't know anything about the longevity of these results yet." Could this be a side effect of first being exposed to these artificial sweeteners? Does it go on indefinitely? ”

The authors of the study issue a warning that additional research on long-term exposure to various artificial sweeteners may be necessary to thoroughly evaluate any potential health impacts brought on by altered microbiomes. The researchers emphasise, however, that their findings should not be construed as a recommendation to replace non-nutritional sweets with additional sugar.

On the other hand, Elinav notes, "Our findings do not endorse or promote the intake of sugar, as sugar consumption still represents a very negative and well-established health risk for obesity, diabetes, and other health implications." On the other hand, the effects of sweeteners that we have demonstrated suggest that prudence is warranted.

According to Katz, this study offers quite conclusive evidence of both deleterious consequences in the short term and of pathways that could result in the same negative effects in the long term. Instead than substituting sugar for other non-nutritive sweeteners, different methods of lowering sugar intake ought to be given priority.

Elinav says, "We need better ways to satisfy our sweet tooth yearning. "In my opinion, sticking to drinking solely water is preferable."