The Truth about Sugar Substitutes and Gut Health

Research shows sugar substitutes alter gut bacteria and should not be assumed to be safe.

New peer-reviewed research finds that 4 common sugar substitutes alter gut bacteria and may harm the ability to process glucose, thereby increasing sugar levels in the body and should not be assumed to be safe.

Previously, it was commonly assumed that sweeteners provided a harmless hit of sweetness without any health cost, however, “Our trial has shown that non-nutritive sweeteners may impair glucose responses by altering our microbiome,” said Immunologist Prof. Eran Elinav of the Weizmann Institute of Science.

The scientists conducted their experiment with the four most common sweeteners: saccharin, sucralose, aspartame, and stevia. The first two appeared to significantly impair glucose response, but all four of them caused changes in the gut bacteria, the microbiome.

artificial sweeteners, microbiome

Image shows glucose levels among trial participants who took different sweeteners, and those who were part of control groups. The control groups are labelled ‘control’ and ‘vehicle.’ (courtesy of the Weizmann Institute of Science.

Elinav stated: “We found that the gut microbe composition and function changes in response to consumption of all four sweetness, meaning that they are not inert to the human body.”

These changes weren’t detected among those in control groups who didn’t consume sweeteners.

They discovered that sweeteners affected the microbiome, which then impacted glucose tolerance — so markedly that it has this effect even if transplanted to another species.

They concluded that, “[non-nutritive] sweeteners are not inert to the human body or to the gut microbiome, as once thought, and may potentially mediate changes in people, possibly in a highly personalized manner stemming from different people’s unique gut microbe populations” and “we should not assume they are safe until proven otherwise. Until then, caution is advised.” 

Enjoy some of “Marsha’s favourite sugar substitutes”, which are safer and healthier choices.


“Artificial sweeteners can harm sugar levels, shouldn’t be assumed safe – Israeli lab”, Nathan Jeffay, The Times of Israel, Retrieved 28 August 2022 <>.

Marsha Fenwick, C.N.P.  R.R.T.

Marsha is not your typical nutritionist. She began her career 20 years ago as a Registered Respiratory Therapist. Later, she earned her certifications as a Registered Nutritional Consultant Practitioner, Certified Nutritional Practitioner, and Registered Orthomolecular Health Practitioner. Marsha is also a Certified Cancer Coach. Her clinical practice specializes in: sustainable healthy weight loss, digestive health, women's hormones, diabetes, heart health, and cancer prevention and recovery. For more information and to book a FREE 15 minute consultation go to

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