When sweeteners undermine blood sugar control and disrupt the microbiota

Guilt-free pleasure, the sweet taste of sugar without either the calories or the health problems (obesity, diabetes etc.) likely to rear their ugly heads if we eat too much: such is the promise of sweeteners, these sugar substitutes that we add to drinks, “diet” fizzy drinks and even “diet” cookies, which are increasingly popular among consumers. Could they be too good to be true? That is what an Israeli study of 120 adults asked to use one of four sweeteners for two weeks (sucralose, saccharine, aspartame or stevia) suggests.

A varying impact on blood sugar, depending on the individual

Ironically, some of the groups taking the sugar substitutes (sucralose and saccharine) soon recorded an abnormal rise in their blood levels of...sugar (glycemia). However, within a single group, there was a wide range in glycemic response between individuals. Given this variability, the researchers turned their attention to the gut microbiota gut microbiota, which is specific to each person and already known to play a direct role in digestion. They found that the four sweeteners, affected the composition of the intestinal (and oral) microbiota and/or its functions, each in its own way. These changes were correlated to the effects on blood sugar levels, suggesting a causal link.

The gut microbiota, a “hangout” for sweeteners

Wanting to be sure of their findings, the researchers transferred the gut microbiota of the participants into axenic (sidenote: Germ-free mice mice that have no microbes at all, raised in sterile conditions. ) mice. In confirmation of their hypothesis, this sole step was enough to reproduce in the recipient mice the same glycemic responses observed in their respective donors. In other words, the mice had a higher blood sugar level if they had received microbiota from participants whose blood sugar level was also affected. This led the researchers to compare the microbiota to a center of reactivity, producing a greater or lesser reaction to sweeteners depending on its make-up.

Although some individuals seem better protected by their microbiota against sweeteners than others, these results cast serious doubt onto the supposed inertia of these substances. Pending further studies to clarify the health recommendations, your next can of soda, whether sugar-full or sugar-free, may leave a bitter taste in your mouth.