Summary of “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”

CITATION & LINK: Nutrients 2020, 12, 3408; doi:10.3390/nu12113408

AUTHORS: Ahmad SY, Friel J and Mackay D.  

REVIEWER: CCC Staff

OBJECTIVE:

• To determine the effect of sucralose and aspartame consumption on gut microbiota composition using realistic doses of non-nutritive sweeteners (NNS).

BACKGROUND:

• In recent years, research interest has focused on the interaction between the microbiota and the host and how the human gut microbiota composition may potentially have an effect on the development of certain diseases, such as metabolic syndrome, obesity and diabetes. More recently, NNS research has focused on the effect of NNS on the gut microbiota.
• There is currently no clinical trial that has investigated the effects of aspartame or sucralose at levels reflecting the high habitual diet soda intake in healthy participants, or has addressed their possible effect on the gut microbiome.
• This study aimed to determine the effect of sucralose and aspartame consumption on gut microbiota composition, diversity, and community structure and the effect of sucralose and aspartame consumption on short-chain fatty acids (SCFAs) (microbiota metabolites).
• This is the secondary outcome of a previously published clinical trial.

METHODS:

• The current study is a randomized, double-blind crossover and controlled clinical trial that took place in the Richardson Centre for Functional Foods and Nutraceuticals (RCFFN) at the University of Manitoba in Winnipeg, Canada.
• A total of 17, healthy participants, aged 18-45 and of normal BMI, consented to follow and complete a 12-week diet regimen in a crossover design:
  • First four weeks: (Baseline period) No NNS were consumed.
  • Weeks 5-6: Nine participants were randomly assigned to consume aspartame; Eight participants consumed sucralose.
  • Weeks 7-10: (Washout period) No NNS were consumed.
  • Weeks 11-12: All participants consumed the sweetener that they did not previously consume.
• The amount each participant consumed was determined based on the average body weight in adults to meet 14% of the ADI for aspartame (approximately equivalent to 0.425 g or 10 packets) and 20% of the ADI for sucralose (approximately equivalent to 0.136 g or 10.5 packets). These dosages are based on the patterns of regular soft drink intake in Canadian men and women. The authors note that, while this dosage level is high, it is reasonable and realistic, reflecting the intake of consumers, who drink approximately three cans of diet soda a day.
• Participants were advised to avoid consuming any NNSs during the study period and were taught about the hidden sources of any NNSs in different foods, beverage products and medication. There were also restricted from consuming alcohol, probiotics and ibuprofen due to their effect on gut microbiota function and composition.
• All anthropometric and biochemical measurements were performed on the first day after a 10- to 12-h overnight fast. During the intervention periods, a baseline fasting blood and fecal samples were drawn at day 1 and then at the beginning and end of each treatment period (i.e., days 28, 42 and 84).

FINDINGS:

• The gut microbiota richness and evenness in the fecal samples did not change following aspartame or sucralose consumption.
• No differences were seen in the number of observed species before or after consumption of either sweetener.
• Across treatment groups, the relative proportions of the most abundant bacterial phyla and genus-level taxa were similar before and after treatments (p > 0.05), and the microbiota community structure did not show any obvious differences.

CONCLUSIONS:

• Daily oral consumption of beverages sweetened with 136 mg/day sucralose or 425mg/day aspartame did not measurably effect the gut microbiota in healthy participants.
• No changes in the gut microbiota structure were detected.
• SCFAs were also unaffected by aspartame and sucralose consumption.

POINTS TO CONSIDER:

• Though the intervention period of the current study was relatively short in duration, the inclusion of washout and multiple treatment periods strengthen the design of the trial.
• The design of this study is also limited, as the primary study was powered to determine the effect of NNS on blood glucose levels, and not their effect on the gut microbiota (an exploratory outcome).