Many people turn to artificial or so-called natural sweeteners to cut calories and lose weight. A new study led by Dr. Raylene Reimer, PhD, at the University of Calgary, published in the high-impact journal Gut, discovered that the consumption of low-calorie sweeteners while pregnant increased body fat in their offspring and disrupted their gut microbiota — the trillions of bacteria and other micro-organisms that inhabit the intestinal tract and affect our health and risk of numerous diseases.

The findings are significant as they impact the critical early years of life, particularly during pregnancy and breast-feeding.

“Low-calorie sweeteners are considered safe to consume during pregnancy and lactation. However, evidence is emerging from human studies to suggest they may increase body weight and other cardiovascular risk factors,” says Reimer, a professor in the Faculty of Kinesiology, and Department of Biochemistry and Molecular Biology at the Cumming School of Medicine, and member of the Alberta Children’s Research Institute.

Photo above, from left: Dr. Erin Noye Tuplin, PhD; Dr. Raylene Reimer, PhD; and PhD student Fatima Chleilat. Photo by Riley Brandt, University of Calgary

“Even stevia, which is hailed as a natural alternative to aspartame and other low-calorie artificial sweeteners, showed a similar impact on increasing offspring obesity risk in early life.”

Aspartame, an artificial sweetener, and stevia, a natural low-calorie sweetener extracted from a plant native to South America, are 200 to 400 times sweeter than sugar. Stevia, gaining popularity, was historically used in Paraguay and Brazil to treat diabetes and is an emerging ingredient in many natural products and protein drinks.

Demand for sweeteners for weight loss

In response to higher obesity rates, the use of low-calorie sweeteners has risen, particularly in women and children. Daily consumption is associated with large babies and early menstruation in young females under 10 years — a known risk factor for chronic diseases. Additionally, the presence of some but not all of these sweeteners has been detected in breast milk, presenting a potential mode of transmission, according to the study.

“Understanding the impact of dietary ingredients on maternal metabolism and gut microbiota may help to define the optimal maternal diet, one which promotes a healthier future for both mother and child,” says Reimer.

Altering the gut microbiota of babies

Our understanding of how sweeteners affect weight gain is not complete but there is reason to believe that alterations in the gut microbiota may play a key role. In this animal study, a fecal transplant was used to show the direct influence of altered gut microbiota on the increased obesity risk. Transplanting fecal matter from the offspring of mothers who consumed the low-calorie sweeteners into sterile, germ-free mice caused the mice to gain more weight and have worse blood glucose control. Even though the offspring had never consumed the sweeteners themselves, the changes to mom’s microbiota and metabolism were sufficient to change the microbiota in their offspring and trigger obesity.

“A healthy pregnancy, including good nutrition, is important for a healthy baby,” says Reimer. “Our research will continue to examine what makes an optimal diet, and more importantly, seek to find ways to correct disruptions to gut microbiota should they occur.”

About the International Microbiome Centre

The International Microbiome Centre at UCalgary is the largest microbiome research facility at an academic institution in the world. It allows researchers to investigate how the microbiome from various sites of the body control organ function. Find out more about microbiome research at UCalgary.

UCalgary has partnered with the Canadian Museum of Nature in Ottawa to help people better understand the microbiome’s influence on our body and disease, and how we might be able to harness the power of the microbiome to cure illnesses. The museum is hosting the Canadian premiere of a travelling exhibit entitled Me and My Microbes: The Zoo Inside You until March 29, 2020. Watch for Guts Talks by UCalgary researchers. Raylene Reimer will be holding a lecture on Feb. 6 at the Canadian Museum of Nature in Ottawa.

This research was supported by a Canadian Institutes of Health Research grant. Trainee support was provided by the Alberta Children’s Hospital Foundation, Canadian Institutes of Health Research, Talisman Energy Fund Healthy Living and Injury Prevention Studentship, Alberta Innovates Health Solutions, Eyes High Doctoral Scholarship, Vanier Canada Graduate Scholarship, and Faculty of Kinesiology Dean’s Doctoral Scholarship.