The common sugar-free sweetener sorbitol may damage your liver in the same way as the older sweetener fructose, researchers found, triggering processes linked to fatty liver disease in people without a history of drinking alcohol.

“The most surprising finding from the current work is that because sorbitol is essentially ‘one transformation away from fructose,’ it can induce similar effects,” senior author Gary Patti, professor of chemistry, genetics and medicine at Washington University Medicine, told SciTechDaily.

Gut microbes play a key role.

“If you have the right bacteria, 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.”

In studies with zebrafish — whose digestive processes resemble those of humans — researchers from Washington University in St. Louis, Missouri, found that fish with gut biota depleted by antibiotics converted glucose and sorbitol into fructose in the intestines, leading to an unhealthy buildup of fat in the liver.

Sorbitol, touted for its low-calorie count and marketed as diabetes-friendly, behaves much like fructose in the body under these conditions. Fructose, coming in at 4 calories per gram, is popularly used in soft drinks and processed foods because it does not interact with blood insulin. However, it has been strongly tied to liver disease affecting up to 25% of adults and a growing number of younger people.

The liver is the largest organ inside the body and is essential to digesting food, storing energy and clearing poisons from the blood. With few symptoms, most people aren’t diagnosed with fatty liver until it advances towards cirrhosis or liver cancer, according to MedlinePlus. People with type 2 diabetes or prediabetic conditions are most at risk, along with factors like obesity, age and high cholesterol and blood pressure. Symptoms can include being excessively tired or having pain in the upper right part of your abdomen.

The research suggests that sorbitol and fructose can be as bad for your liver as excessive drinking — the other main cause of fatty liver disease — while a healthy gut biome helps protect your liver. Regular, low levels of sorbitol are not likely to cause harm, the researchers said.

They published their findings in Science Signaling.

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