They promise to offer sweetness to food and drink, without adding kilocalories to our diet. Long accompanied by an aura of healthiness, artificial sweeteners may actually not be without consequences for our health. The first suspicions date back to eight years ago, when a group of researchers from the Weizmann Institute of Science in Jerusalem showed that the intake of these molecules altered the intestinal flora of rats. In a way that makes sugar metabolism more difficult. And thus exposing animals to a greater risk of hyperglycemia, if not diabetes. The time that has elapsed has not served to reduce the question, which was re-launched a few weeks ago by a study conducted on a human sample. The conclusions, published in Cell magazine, are already causing discussion. Convinced that it is worthwhile to look cautiously at sweeteners as a solution to consume sweet foods with fewer worries. So at least until further feedback.
The Israeli white coats, who in 2014 were the first to notice an effect on gut bacterial makeup in mice, have completed a trial on more than 1,300 healthy individuals (none of them had ever used artificial sweeteners before the study began). The sample was initially divided into two: a study group (120 people) and a control group. The protagonists of the research were in turn divided into six samples. Four smaller ones, depending on the type of artificial sweetener taken in sachets three times a day and for two weeks: aspartame, saccharin, stevia and sucralose (in doses, however, lower than the limits set by regulatory authorities and therefore considered safe for human consumption) . While the other two were composed of those called to take sugar or no sweetener.
The ability to tolerate sugars also changes
Objective: to evaluate the impact on human health. The effects were the same as those found on animal models. Following the intake of the four sweeteners, in fact, the researchers found variations in the composition of the microbiota of both the intestine and the oral cavity. And in those who consumed saccharin and sucralose, an impaired ability to tolerate sugars was also recorded. A condition that experts consider prodromal to the onset of overweight, obesity and diabetes.
To clarify the origin of this latest finding, obtained by continuously monitoring blood glucose for 29 days, the researchers added a further step to the study. By transferring samples of the intestinal bacteria collected through the feces from these people into sterile rats (without microorganisms in the intestine) and measuring the fluctuations in blood glucose, the results were similar to those obtained in humans. A finding that, according to scholars, confirms the causal link determined by artificial sweeteners on the alterations of the microbiota and on the regulation of blood sugar.
Bacteria change and blood sugar is altered
“Our results show that changes in the pattern of intestinal bacteria can induce changes in blood sugar in consumers,” he warns. They were Elinav, immunologist at the Weizmann Institute and one of the first researchers in the world to strive to understand the impact that artificial sweeteners have on health. A process that researchers call “highly personalized”. And that, also thanks to an observation that is too short to allow definitive conclusions to be drawn, will require further years of study.
Simple sugars? Dangerous
Only afterwards, eventually, will it be possible to translate the scientific evidence into recommendations addressed to the general population. “Simple sugars remain among the most dangerous molecules for our health – explains Elinav -. Having said that, it is on our desire to consume sweet foods that we need to work. Today we can say almost with certainty that sweeteners are not inert for health,” as we thought until about ten years ago “.
What are artificial sweeteners?
Hence the dilemma: is it better to consume (always in moderation) sugar in coffee and among the ingredients of desserts or prefer these sweeteners? Difficult to answer at the moment. The reality shows that, thanks to the increase in the prevalence of overweight and obesity and related diseases, the consumption of artificial sweeteners has grown significantly in the last forty years. These are substances produced in the laboratory – unlike natural sweeteners, recognizable by the ending in “ol”: this is the case of sorbitol, mannitol, xylitol – through a process of chemical synthesis. And characterized by an extremely high sweetening power but with an almost zero calorie content, since they are not absorbed by the body. Among the best known synthetic sweeteners, those “tested” in the study. Hence the interest of the scientific community, intent on understanding what the effects on health can be caused by constant consumption over time.
The most significant evidences, obtained first on an animal model and then on humans, concern the alteration of the intestinal flora. A complex ecosystem of bacteria, fungi and viruses that is sensitive to the components of the diet and on whose composition our health seems to depend. In fact, some bacteria synthesize useful substances (for example vitamin K) and digest complex molecules. Others help keep the intestine healthy, protecting it from inflammation and the onset of tumors.
Because it must be rich in bacteria
Furthermore – according to the scientific evidence collected in the last decade – a microbiota rich in bacteria capable of digesting and fermenting the flavonoids contained in fruit and vegetables promotes the production of substances that have protective effects on cardiovascular health. Conversely, however, foods rich in saturated fatty acids and high-calorie foods stimulate the proliferation of strains that promote inflammation. The alteration (in a negative sense) of the microbiota has been correlated with an increased risk of the onset of various diseases: from diabetes (with all the possible consequences) to various cancers.
Genes play a role on the microbiota
How to behave, then, in the light of these evidences? The difficulty, as admitted by the researchers themselves, lies in “transferring” them into useful advice for the general population. In fact, there cannot be an ideal microbiota that is the same for everyone: genes and individual characteristics play a decisive role in its composition. What can be said at the moment is that the more diverse the microbiota is, the more it appears to be protective of health.