An interview with Stephen Fleming, PhD, Traverse Science
An unhealthy diet high in free sugars is commonly recognised as a risk factor for dental caries which has led to increased interest on the role of low/no calorie sweeteners in oral health. Sweeteners like aspartame, sucralose and stevia do not affect our teeth in the same way that sugar does, and are considered “non-cariogenic”. In this interview, Dr Stephen Fleming, a neuroscientist, co-founder and CEO of Traverse Science, talks about the findings of a new study on aspartame and oral health and explains what the non-cariogenicity of aspartame means.
ISA: Can you tell us about your recent study on aspartame and oral health? Which are the main findings of your work?
Dr. Stephen Fleming: Our systematic review and meta-analysis examined the cariogenicity of aspartame, comparing its effects to sucrose and other controls. The study included evidence from preclinical models, in vitro studies, and human trials. We found that aspartame is non-cariogenic, meaning it does not contribute to tooth decay in the way that sucrose does.
Clinical studies demonstrated that aspartame was less acidogenic than sucrose and maintained oral pH levels comparable to water. Preclinical studies indicated that replacing sucrose with aspartame significantly reduced caries formation in rodents. However, when aspartame was added on top of sucrose, its effect on reducing caries was less clear. Studies on bovine blocks also showed that aspartame was less acidogenic and erosive than sucrose. Overall, the reduction in caries observed with aspartame use is primarily due to its role in minimizing sugar intake rather than an intrinsic anti-cariogenic effect. More long-term human studies are needed to further understand its impact on oral health.
The review has been published in the Journal of Dentistry and can be seen here.
ISA: How do low/no calorie sweeteners affect the oral microbiome and what does this mean for oral health?
Dr. Stephen Fleming: Our analysis found limited evidence that aspartame directly affects the composition of the oral microbiome. In preclinical studies, replacing sucrose with aspartame led to reductions in Streptococcus mutans—a key bacteria involved in caries development—but had little impact on total bacterial abundance or the presence of other species like Actinomyces viscosus or Streptococcus sobrinus. When aspartame was added to sucrose rather than replacing it, there was no significant effect on bacterial populations.
In vitro studies using bovine blocks suggested that aspartame reduces biofilm lactic acid production and may result in lower plaque acidification compared to sucrose. However, studies that compared aspartame to a negative control (such as water) found that it had a similar or slightly higher impact on acid production, suggesting that while it is not cariogenic, it does not strongly inhibit bacterial growth either. In practical terms, this means that using aspartame instead of sugar can help maintain a healthier oral environment, primarily by reducing exposure to free sugars, which are a key driver of tooth decay. However, there is not strong evidence to suggest that aspartame actively alters the microbiome in a way that directly prevents caries.
ISA: Beyond the oral health benefit of using sweeteners in place of sugars, is there evidence supporting an anti-cariogenic potential of low/no calorie sweeteners?
Dr. Stephen Fleming: While replacing sugar with low/no calorie sweeteners is beneficial for reducing caries risk, our study found only limited evidence that aspartame has intrinsic anti-cariogenic properties. In preclinical models, aspartame-fed rodents developed significantly fewer caries compared to sucrose-fed rodents, but this effect was primarily due to the removal of sucrose rather than any direct protective action of aspartame. Some findings suggest that aspartame may have minor cariostatic effects. For example, in bovine block studies, aspartame was associated with reduced mineral loss and erosive wear compared to sucrose. Additionally, preclinical studies found that aspartame combined with sucrose reduced caries development in certain regions of the tooth, such as sulcal caries. However, these effects were not consistently observed across all caries types or study models. Ultimately, the current evidence suggests that aspartame is best described as non-cariogenic rather than actively anti-cariogenic. Future long-term human studies are needed to determine if it has any clinically significant protective effects beyond simply replacing sugar.
For more information about low/no calorie sweeteners and oral health, you may read and download a series of ISA resources including the ISA factsheet “Low/no calorie sweeteners and their beneficial role in oral health” and Chapter 6 of the ISA booklet “Low/no calorie sweeteners: Role and benefits”.
