They discover that artificial sweeteners can cause alterations in the human microbiome

Artificial sweeteners promise us all the sweetness of sugar with hardly any calories. A dream for any sweet tooth. Take care of yourself without giving up pleasure. Today, in addition to being able to add them to coffee to dull the guilt after a meal, we find these additives in many ultra-processed products, especially those that are sold as “light” or zero sugar. It has long been believed that they have no effect on the human body, but a team of researchers has discovered that these sugar substitutes are not inert and, in fact, some can alter the microbiomes of some consumers in ways that change their levels of glucose in the blood. In 2014, the same team, led by Eran Elinav, an immunologist and microbiome researcher at the Weizmann Institute of Science and the German National Cancer Center (DKFZ), already found that artificial sweeteners influenced the microbiomes of mice in ways that could affect your glycemic responses (the effect that drinks and foods have on blood glucose levels after they are eaten). The researchers were now interested in knowing if the same thing happened with people. To find an answer, the team carefully screened more than 1,300 people for those who strictly avoid artificial sweeteners in their daily lives and identified a cohort of 120 participants. These were divided into six groups: two controls and four who ate well below the FDA-recommended maximum daily amounts of aspartame, saccharin, stevia or sucralose. “In subjects who consumed artificial sweeteners, we were able to identify very distinct changes in the composition and function of gut microbes and the molecules they secrete into peripheral blood. This seemed to suggest that gut microbes in the human body are quite responsive to each of these sweeteners,” says Elinav. “When we looked at artificial sweetener consumers as groups, we found that two of them, saccharin and sucralose, significantly affected glucose tolerance in healthy adults. Interestingly, the changes in the microbes were highly correlated with the observed alterations in people’s glycemic responses.” To establish causality, the researchers transferred microbial samples from the study subjects to germ-free mice, which were raised in completely sterile conditions and do not have a microbiome of their own. For the researcher, “the results were quite surprising.” “In all artificial sweetener groups, but none of the controls, when we transferred to these sterile mice the microbiome of the most responsive individuals collected at a time when they consumed the respective sweeteners, the recipient mice developed glycemic alterations that reflected very significantly those of individual donors. In contrast, the microbiomes of those with lower responses were mostly unable to elicit such glycemic responses,” he adds. These results, says the researcher, suggest that changes in the microbiome in response to human consumption of non-nutritive sweeteners can sometimes induce glycemic changes in a »highly personalized« way. »We need to raise awareness that sweeteners are not inert to the human body as we originally believed. That said, the clinical implications for health of the changes that they can cause in humans remain unknown and deserve future long-term studies,” acknowledges Elinav. Cell/Suez et al María del Mar Malagón, president of the Spanish Society of Obesity (SEEDO), points out that the idea that emerges from this study, and that comes from previous work, is that sweeteners can change the microbiota, but she is cautious: «From the authors’ conclusions we cannot say that sweeteners are harmful to health but there are individual responses to sweeteners: Some people may be affected and others not. More studies are needed to see why these people are affected and which ones affect them”. In the opinion of Dr. María Riestra, member of the nutrition area of ​​the Spanish Society of Endocrinology and Nutrition (SEEN), what is interesting about the current study is that “for the first time it has been shown that the consumption of sweeteners produces ca Changes in the microbiota in humans, that is, in the different microorganisms that make up our intestinal flora, and that these changes can be detrimental to maintaining the balance in glucose levels, and can predispose to different diseases, such as type 2 diabetes. Simply put, the bacteria in our gut are swapped out for ones that predispose to diabetes when we over-consume artificial sweeteners.” Dr. Riestra acknowledges that the data is still preliminary and more significant studies are needed before reviewing the recommendations on the consumption of sweeteners, but advocates moderation: “The truth is that health professionals should promote the consumption of real foods, avoiding ultra-processed foods as much as possible, since many contain hidden sweeteners in their composition, such as products labeled “light” or “suitable for diabetes”. Its consumption should be limited, but today, a very occasional use should not be harmful, and it will always be better than products with sugar, within a majority consumption of a healthy diet”. More critical of the study is Francisco Guarner, director of the Digestive System Research Unit at the Vall d’Hebron University Hospital in Barcelona and former president of the Spanish Society of Microbiota, Probiotics and Prebiotics (SEMiPyP).In SMC Spain, the expert says that “it is not a definitive study or of great quality”. “The new publication is not a clinical study, but rather an experimental study: the N (the number of individuals in the study) is low, they did not enroll people with insulin resistance and use exorbitant doses of sweetener “, he writes. He also emphasizes that “they did not detect this negative effect in individuals who treated with stevia or with aspartame. Therefore, the slightly negative effect should not be attributed to all sweeteners ». In his opinion, «there is only one acceptable conclusion, which is also important: the fact that a substance is not absorbable and, therefore, does not pass into the blood, does not mean that it is inert. The substance influences the microbiota of the large intestine and can induce negative or positive changes.”