Sorbitol: The ‘Healthy’ Sugar Substitute Linked to Liver Disease, New Research Reveals
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A growing body of evidence challenges the notion that sugar alcohols like sorbitol offer a harmless choice to refined sugar, with a recent study suggesting a potential link to liver dysfunction. Published in Science Signaling in July 2025, the research indicates that sorbitol, commonly found in “low-calorie” products and stone fruits, can be converted into fructose in the liver, triggering similar harmful effects as excessive fructose consumption.
The Fructose Connection and Liver Health
For years, scientists have understood the detrimental effects of high fructose intake on the liver and overall health. Previous research from the lab of Gary Patti, the Michael and tana Powell Professor of Chemistry at Washington University in St. Louis, has shown that the liver readily processes fructose, but excessive amounts can lead to non-alcoholic fatty liver disease (NAFLD). The new study builds on this understanding, revealing that sorbitol is “one transformation away from fructose,” meaning the body can readily convert it into fructose within the liver. Experiments with zebrafish showed that sorbitol, present in candies, gums, and naturally occurring in certain fruits, is created by enzymes in the gut and ultimately metabolized into fructose.
“There are manny roads to fructose in the liver, and potential detours,” explained a senior researcher involved in the study, highlighting the complex interplay between dietary intake, gut bacteria, and metabolic processes.
The Role of Gut Bacteria
The body’s ability to process sorbitol is heavily influenced by the composition of gut bacteria. Certain strains, like Aeromonas, can effectively break down sorbitol into harmless byproducts. However, if these beneficial bacteria are absent or overwhelmed, sorbitol remains intact and is passed on to the liver for conversion into fructose.
“If you have the right bacteria, it doesn’t matter,” a professor at Washington University in St. Louis stated. “However, if you don’t have the right bacteria, that’s when it becomes problematic.”
While sorbitol production is frequently enough associated with diabetes due to elevated glucose levels,the research indicates that even individuals with healthy metabolisms can produce notable amounts of sorbitol in the gut after consuming meals. The enzyme responsible for sorbitol production requires high glucose levels to function effectively, but even moderate increases in gut glucose can trigger its activity.
Implications for ‘Sugar-Free’ Diets
These findings raise concerns about the widespread use of sorbitol and other sugar alcohols in “sugar-free” products, notably for individuals with diabetes or other metabolic disorders. The study underscores the importance of understanding whether these alternative sweeteners truly offer a healthier option compared to traditional sugar.
The research team observed that even when gut bacteria are present to clear sorbitol, excessive consumption of glucose and sorbitol can overwhelm their capacity. This suggests that a high-sugar,high-sorbitol diet can negate the benefits of a healthy gut microbiome.
A Complicated Landscape
Navigating the world of sweeteners is becoming increasingly complex, as many processed foods contain a combination of sugars and sugar alcohols. The lead researcher even noted discovering a significant amount of sorbitol in his own favorite protein bar. Further research is needed to fully understand the mechanisms by which bacteria clear sorbitol and to determine the long-term effects of chronic sorbitol exposure.
“We do absolutely see that sorbitol given to animals ends up in tissues all over the body,” the professor confirmed.
Ultimately, the research suggests that “there is no free lunch” when seeking sugar alternatives, with multiple pathways potentially leading to liver dysfunction.
Source: Washington University in St. Louis
Journal reference: Jackstadt, M. M.,et al. (2025). Intestine-derived sorbitol drives steatotic liver disease in the absence of gut bacteria. Science Signaling. doi: 10.1126/scisignal.adt3549. https://www.science.org/doi/10.1126/scisignal.adt3549
