The Effects of Non-Nutritive Artificial Sweeteners, Aspartame and Sucralose, on the Gut Microbiome in Healthy Adults: Secondary Outcomes of a Randomized Double-Blinded Crossover Clinical Trial

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Author(s): Ahmad SY, Friel JK, MacKay DS.
Publication name: Nutrients 2020; 12(11): 3408. Doi:10.3390/nu12113408
Publication year: 2020


Non-nutritive artificial sweeteners (NNSs) may have the ability to change the gut microbiota, which could potentially alter glucose metabolism. This study aimed to determine the effect of sucralose and aspartame consumption on gut microbiota composition using realistic doses of NNSs. Seventeen healthy participants between the ages of 18 and 45 years who had a body mass index (BMI) of 20–25 were selected. They undertook two 14-day treatment periods separated by a four-week washout period. The sweeteners consumed by each participant consisted of a standardized dose of 14% (0.425 g) of the acceptable daily intake (ADI) for aspartame and 20% (0.136 g) of the ADI for sucralose. Faecal samples collected before and after treatments were analysed for microbiome and short-chain fatty acids (SCFAs). There were no differences in the median relative proportions of the most abundant bacterial taxa (family and genus) before and after treatments with both NNSs. The microbiota community structure also did not show any obvious differences. There were no differences in faecal SCFAs following the consumption of the NNSs. These findings suggest that daily repeated consumption of pure aspartame or sucralose in doses reflective of typical high consumption have minimal effect on gut microbiota composition or SCFA production.


The results of a secondary analysis of data from the current randomised controlled trial showed that aspartame and sucralose did not cause measurable changes in the gut microbiota or in short-chain fatty acids after 14 days of a realistic daily intake of these two low/no calorie sweeteners in healthy participants. This study also found no effects of pure aspartame and sucralose ingestion on glucose metabolism and insulin sensitivity in healthy adults (Ahmad et al, 2020).

This is one of the first human studies to assess the effects of repeated daily oral intake of beverages sweetened with a pure powder of sucralose or aspartame by healthy adults on the human microbiome. It showed no measurable impact on the gut microbiota in healthy participants, nor any change in the gut microbiota structure. Short-chain fatty acids (SCFAs) production was also unaffected by aspartame and sucralose consumption. The doses of low/no calorie sweeteners used in this study resemble an intake of approximately three cans of beverages per day.

This study by Ahmad et al is an important addition to the scientific literature and informs further research on the relationships between low/no calorie sweeteners, glucose metabolism and the gut microbiota in the context of human health and disease. The findings of this human trial do not confirm claims by some microbiome studies conducted in animal models that suggest that low/no calorie sweeteners might negatively affect gut microbiota. Experts warn that there are large differences between the gut microbiome profile in laboratory animals and people, so translating data from animal studies that test effects of high doses of low/no calorie sweeteners to humans is very suspect. Current data establish no evidence of any adverse effect of low/no calorie sweeteners on the human gut microbiota and at doses relevant to human use.

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