An atlas of the brain and pointing out the hippocampus in Dana Small's lab at the Modern Diet and Physiology Research Center on September 21, 2023 in New Haven, Connecticut.
An atlas of the brain and pointing out the hippocampus in Dana Small’s lab at the Modern Diet and Physiology Research Center in New Haven, Connecticut.

Unveiling the Controversy Around Artificial Sweeteners

Published in the Financial Times

Artificial sweeteners have always carried a controversial reputation, and recent research is reigniting the debate. Professor Dana Small, a psychiatry expert from Yale University, made a surprising discovery when investigating artificially sweetened drinks’ impact on the brain and gut.


Her study revealed that participants who consumed sucralose-sweetened beverages experienced no adverse effects. However, the group that consumed the same drink with added liquid carbohydrates showed signs of impaired metabolism, leaving them susceptible to weight gain and glucose intolerance. Small referred to this finding as “a smoking gun,” questioning the recommendation of diet sodas for people with diabetes if consumed with certain foods like french fries.

Portrait of Dana Small at the Modern Diet and Physiology Research Center
Portrait of Dana Small at the Modern Diet and Physiology Research Center


Published in 2020, Small’s study contributes to the growing body of evidence challenging the assumption that sweeteners offer a safe way to satisfy sugar cravings without the associated risks. However, it also highlights the limited understanding of the physiological impact of the various sweeteners present in today’s supermarket shelves.


The history of artificial sweeteners is plagued with safety concerns that date back to the commercial production of saccharin in 1886. Matters intensified in 1977 when a Canadian study linked saccharin to bladder tumors in rats. Although the industry heavily contested these findings, saccharin remained on the list of known carcinogens until 2000.


The controversy resurfaced in May when the World Health Organization (WHO) recommended against using non-sugar sweeteners to support weight loss or maintain healthy blood glucose levels. The WHO cited evidence suggesting potential undesirable effects from long-term sweetener use, including an increased risk of type 2 diabetes, cardiovascular diseases, and mortality in adults. In July, the WHO’s International Agency for Research on Cancer went on to classify aspartame, a widely used sweetener, as “possibly carcinogenic to humans.”

Bottles of mixtures to be consumed in a trial
A tray used for portioning out mixtures to be consumed by test participants
A mock scanner and feeding tubes used to help train test subjects
A mock scanner and feeding tubes used to help train test subjects

Dr. Jotham Suez from Johns Hopkins University echoes these concerns, noting that sweeteners may be damaging based on research linking them to altered gut bacteria and disrupted blood glucose levels. The gut microbiome plays a significant role in metabolic health and cancer formation, warranting caution.

While some experts question the significance of these effects and call for more research, the benefits of artificial sweeteners may be overstated. The industry claims that sweeteners provide safe alternatives to reduce sugar and calorie intake, but they should not be viewed as dietary panaceas. The understanding of sweeteners’ impact on individuals may be personalized and requires further exploration.

The uncertainty surrounding sweeteners is influencing scientists, policymakers, manufacturers, and consumers. As food and drinks companies seek to reduce costs and comply with sugar taxes, they have replaced sugar with sweeteners in thousands of products. However, concerns persist, with studies showing increased intake of sweeteners among both adults and children.

Dana Small in her office.

Manufacturers are navigating the shifting landscape by switching to “natural” sweeteners to address negative consumer perceptions. Despite claims that natural and artificial sweeteners are similar from a food safety perspective, consumer attitudes often favor natural options. Companies like Tate & Lyle and Ingredion are investing in stevia, a popular natural sweetener, in response to market demand.

Regulatory crackdowns are not expected in the near future, but companies are exploring alternatives and experimenting with sugar reduction strategies. Nestlé has developed a sugar-reduction technology that uses enzymes to reduce intrinsic sugar in ingredients. Additionally, the use of fibers and sweet proteins derived from African fruits is being explored to reduce the sweetness of products.

With multiple types of sweeteners available, more research is necessary to fully understand their effects. Large-scale human studies are crucial, as evidence suggests that artificial sweeteners have an impact on the body. Striking the right balance between reducing sugar consumption and avoiding potential health risks remains an ongoing challenge that requires clarity and further scientific investigation.

Dana Small at her computer in the Modern Diet and Physiology Research Center
Dana Small at her computer in the Modern Diet and Physiology Research Center