Sweeteners are often seen as a healthier alternative to products containing refined sugars, such as glucose. Common types of sweeteners include aspartame (used in products like Equal), sucralose (Splenda), and sugar alcohols like sorbitol.

However, recent research suggests that these alternatives are not always safer than sugar. A recent study published in Science Signaling found that sorbitol can have metabolic effects that make it less harmless than previously thought.

Sorbitol Metabolism and Its Connection to Fructose

This study continues a series of works dedicated to the effects of fructose on the liver and other organs. Previous research established that fructose metabolism products can be used by cancer cells for growth and are linked to the development of fatty liver disease—a condition where excess fat accumulates in the liver (affecting about 30% of adults worldwide).

Sorbitol is closely related to fructose in terms of metabolic pathways. The body can convert sorbitol into compounds similar in effect to fructose. Sorbitol is often added to low-calorie sweets and chewing gums, and it also occurs naturally in some fruits.

How Sorbitol Is Formed and Absorbed

Experiments on zebrafish have shown that sorbitol can be produced not only from food but also synthesized in the gut from glucose after eating. The fate of sorbitol depends on the amount of glucose and sorbitol consumed, as well as the composition of the gut microbiota.

Certain bacteria, such as Aeromonas strains, can break down sorbitol and convert it into harmless byproducts. If there are not enough of these bacteria, sorbitol is not broken down and can enter the liver, where it is converted into fructose derivatives.

Effects on the Body and Risks

It was previously believed that sorbitol production in the body was mainly associated with diabetes, since the enzyme responsible for its synthesis is activated at high glucose concentrations. However, studies have shown that even under normal conditions, after eating, glucose levels in the gut can be sufficient for significant sorbitol formation.

In small amounts, such as those from fruit, gut bacteria efficiently remove sorbitol. However, with high intake of glucose or sorbitol, the capacity of the microbiota can be exceeded, and some sorbitol reaches the liver.

This is especially important for people with diabetes and other metabolic disorders, who often choose products labeled "sugar-free" to reduce the risk of negative effects from regular sugar. It is important to remember that alternative sweeteners do not always provide a more favorable metabolic outcome.

Features of Sugar Alcohols

Sorbitol belongs to the group of polyols, or sugar alcohols, which are widely used for their sweet taste and lower calorie content compared to regular sugar. It was previously assumed that these compounds are excreted from the body without serious metabolic consequences, but new data indicate more complex processes.

Conclusion

Research shows that replacing regular sugar with other sweet components does not always eliminate metabolic consequences. This is especially relevant when several metabolic pathways can lead to impaired liver function. Therefore, choosing sweeteners requires careful consideration of individual metabolic characteristics and the composition of the gut microbiota.