Do you reach for labels such as ‘sugar-free’, ‘low-calorie’, or ‘guilt-free’, thinking they’re the healthier choice? You are not alone. As we live in an era where diabetes and other lifestyle diseases have become increasingly prevalent, most people are turning to alternative sweeteners. People are swapping refined sugar for sweeteners such as aspartame, sucralose, or sugar alcohols; however, are these alternatives really safe? A new study by researchers at Washington University in St. Louis found that sorbitol, a common sugar alcohol found in low-calorie foods and beverages, may not be as harmless as once believed. The findings of the study were published in the journal Science Signaling.
Not so sweet
In the United States, about 38.4 million people had diabetes, according to CDC data in 2024. What’s more problematic is that 8.7 million people are unaware they have the condition. For years, sorbitol has been positioned alongside aspartame and sucralose as a healthier pick over refined sugar. However, the new research, led by Gary Patti at Washington University, is challenging that assumption. In their previous research, the team uncovered how fructose metabolism in the liver can fuel cancer cells and contribute to steatotic liver disease. Adding to this, the current work discovered that sorbitol is essentially “one transformation away from fructose” and can induce similar effects.
Sorbitol’s impact on the body
The researchers found that sorbitol, a sugar alcohol found in low-calorie snacks, protein bars, and sugar-free products such as gums, cough syrups, and stone fruits, has the same effect as fructose, a key contributor to steatotic liver disease, which affects 30% of the adult population worldwide. Using zebrafish models, Patti’s team found that sorbitol is naturally made by enzymes in the gut and eventually converted into fructose in the liver. “For starters, although most of the research on sorbitol metabolism has focused on its production due to glucose overload in pathological settings such as diabetes, sorbitol can be naturally produced in the gut from glucose after eating,” Patti said. Later, sorbitol moves from the gut to the liver, where it is converted into a fructose derivative. As fructose is a major driver of fatty liver disease, this conversion pathway is concerning. The enzyme that produces sorbitol has a low affinity for glucose, which means glucose levels must be high for it to act. This is why sorbitol production has traditionally been linked to diabetes, where blood glucose levels can rise significantly. But the researchers have now found that even in healthy conditions, glucose levels in the gut become sufficiently elevated after feeding to trigger sorbitol production within the intestine. “It can be produced in the body at significant levels. But if you have the right bacteria, it turns out, it doesn’t matter,” Patti said. “However, if you don’t have the right bacteria, that’s when it becomes problematic. Because in those conditions, sorbitol doesn’t get degraded and, as a result, it is passed on to the liver,” he added. When it reaches the liver, it is converted to a derivative of fructose.
What does this mean?
Avoiding both sugar and sugar alternatives may not be as easy as you assume because many products blend multiple sweeteners. So, avoiding sorbitol is far from easy. During the research, Patti was bemused to discover that his own favourite protein bar was filled with sorbitol. The researchers noted that more studies are needed to understand the specific mechanisms by which bacteria clear sorbitol, but the basic idea that these sugar alcohols, called polyols, are harmlessly expelled may not hold true. “We do absolutely see that sorbitol given to animals ends up in tissues all over the body,” he said.Note: The information provided in this article is for educational purposes only and is not intended as medical advice. Always consult a qualified healthcare professional before starting any new medication or treatment, or before changing your diet or supplement regimen.
