Can Common Artificial Sweeteners Harm Your Liver? New Study Says Yes

A recent study found that artificial sweeteners like sugar alcohol sorbitol affect the liver and other organs. Artificial sweeteners are usually promoted as healthier alternatives to refined sugar and people consume them. However, recent studies have highlighted that these options might not really be as healthy as people presume them to be. The study was published in the journal Science Signaling and was conducted at the laboratory of Gary Patti at Washington University in St. Louis. Patti is the Michael and Tana Powell Professor of Chemistry in Art & Sciences and of genetics and medicine at WashU Medicine.

His earlier studies have shown that fructose that's processed by the liver can be diverted in ways that can lead to cancer cell growth. Other studies have also linked fructose to steatotic liver disease. Also known as fatty liver disease, it is a condition that affects nearly 30% of adults across the world. When there's a fat buildup in the liver, it is known as fatty liver disease. It can become a problem when the fat deposit reaches 5% of your liver's weight.

Patti says that one of the most unexpected results of the new study is that one of the most unexpected results of the new study is that sorbitol is essentially "one transformation away from fructose". Due to this, sorbitol can have similar effects like that of fructose. The researchers used zebrafish as a model for the study and found that sorbitol can be produced inside the body. Enzymes in the gut can generate sorbitol, which is then transported to the liver and converted into fructose. Researchers also found that the liver also receives fructose through multiple metabolic routes.

Past research on sorbitol metabolism have focused on diseases like diabetes, where increased blood sugar triggers excess production. However, as Patti notes, the gut naturally generates sorbitol after meals, even in healthy people without diabetes.

The enzyme at the heart of this process has a low affinity for glucose. This means that glucose concentrations must increase to an unusually high level before the enzyme converts it into sorbitol. This characteristic has been linked with sorbitol production to hyperglycemia in diabetes. However, the new study using zebrafish has demonstrated that intestinal glucose levels can spike high enough after eating which can activate this pathway and generate meaningful amounts of sorbitol. Patti said, "It can be produced in the body at significant levels. But if you have the right bacteria, turns out, it doesn't matter."

Not all gut microbes are created equal when it comes to handling sorbitol. Certain strains of Aeromonas bacteria have the enzymatic machinery to efficiently ferment and break down sorbitol, transforming it into inert bacterial byproducts like short-chain fatty acids or gases. When these beneficial bacteria are abundant and metabolically active, they act as a robust first line of defense, preventing sorbitol from escaping the gut.

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."

Upon reaching the liver, sorbitol undergoes further transformation that can lead to fat accumulation. This revelation raises serious questions about the safety of sugar alcohols like sorbitol and others, which are staples in "sugar-free" products for people with diabetes, insulin resistance, or other metabolic disorders.

In everyday scenarios, consuming sorbitol at low levels that's naturally present in whole fruits like apples, pears, or peaches, the gut microbiome typically manages to clear without issue. Challenges start only when sorbitol production or intake surpasses the processing capacity of the microbes.

This overload can happen when an individual consumes large amounts of glucose, leading to increased production of sorbitol from glucose, or when the diet itself contains high levels of sorbitol. Even people with good bacteria may have problems if their glucose and sorbitol consumption becomes too high.

Navigating this has become even trickier as processed foods often have multiple sweeteners. Patti shared a personal anecdote wherein he said that he was startled to discover a substantial amount of sorbitol in his favorite protein bar. Patti added, "We do absolutely see that sorbitol given to animals ends up in tissues all over the body." The highlight of this research challenges the narrative around sugar replacement.

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