If you’re trying to lose weight, then sugar is one of your main enemies. But everybody wants something sweet once in a while, so artificial sweeteners were invented, and in recent years, they’ve become quite popular. But now, a new study shows that artificial sweeteners are messing with our gut bacteria, also causing high sugar levels in our blood.

This seems pretty weird; our bodies can’t digest artificial sweeteners, so then how is it that they’re causing increased sugar levels? A team from the Weizmann Institute of Science in Israel found that artificial sweeteners are messing with our stomach’s “fauna” – the bacteria which inhabit our gut -, triggering glucose intolerance in the body – which is the first step towards metabolic syndrome and adult-onset diabetes.

“Our results suggest that in a subset of individuals, artificial sweeteners may affect the composition and function of the gut microbiome,” Eran Elinav, an immunologist and co-author of the study, explained at a press conference.

To understand exactly how this is happening, researchers analyzed three artificial sweeteners: aspartame, sucralose and sacchari; they found that all three of have an effect even stronger than sugar. The substances led to an increase in the bacterial fauna population, increasing the sugar levels.

Researchers then gave mice antibiotics, which interestingly enough wiped out the entire bacteria population, sending sugar levels back to normal values.

“This, in itself, was conclusive proof that changes to the gut bacteria are directly responsible for the harmful effects to their host’s metabolism. The group even found that incubating the microbiota outside the body, together with artificial sweeteners, was sufficient to induce glucose intolerance.”

After settling the issue on mice, they moved on to humans. Similar effects were observed – eating artificial sweeteners causes gut bacteria to thrive, raising the sugar levels in the blood, more than eating the same amount of sugar.

“Elinav believes that certain bacteria in the guts of those who developed glucose intolerance reacted to the chemical sweeteners by secreting substances that then provoked an inflammatory response similar to sugar overdose, promoting changes in the body’s ability to utilise sugar,” the press release explains.

So, while the exact underlying mechanisms remain to be figured out, and while researchers study why some bacteria are affected and some not, the takeaway message is really simple: avoid artificial sweeteners – they do more harm than sugar.

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