Does Trehalose Cause Diarrhea? Understanding Sugar and Digestive Health

December 28, 2025 •

4 min read

While trehalose is considered safe for most people and holds a GRAS status from the FDA, it can cause diarrhea in individuals who have a rare genetic condition called trehalase deficiency. For others, digestive upset is primarily a matter of dosage, as high intake can overwhelm the digestive system and cause osmotic diarrhea.

Quick Summary

Trehalose may cause diarrhea, especially in individuals with trehalase deficiency who cannot break down this sugar, or in healthy people consuming very high doses. The undigested sugar draws water into the intestines, causing discomfort, gas, and loose stools.

Key Points

Trehalase Deficiency: This rare genetic condition is the primary cause of trehalose-induced diarrhea, as affected individuals lack the enzyme needed for proper digestion.
High-Dose Overload: Consuming very large amounts of trehalose can cause temporary malabsorption and osmotic diarrhea even in healthy people, as their digestive system can become overwhelmed.
Osmotic Mechanism: When trehalose isn't absorbed, it pulls excess water into the colon, leading to loose stools, bloating, and gas.
Dose Dependency: Studies show a threshold exists for trehalose's laxative effect in healthy subjects, with some experiencing symptoms at around 25g, though individual tolerance varies.
Rare but Notable: Trehalase deficiency is more common among Greenland's population than in other parts of the world, though still rare overall.
Microbiome Interactions: While initial concerns linked trehalose to certain C. difficile strains, later studies found no evidence of a direct causation, and some suggest potential prebiotic effects.

What is Trehalose?

Trehalose is a naturally occurring disaccharide, or double sugar, composed of two glucose molecules joined by an α,α-1,1 glycosidic bond. This unique bond makes it more stable under heat and acidic conditions compared to other sugars. It is naturally found in a variety of organisms, including certain mushrooms (like shiitake), baker's yeast, honey, shrimp, and insects. The industrial production of trehalose from starch has led to its widespread use as a food additive in a range of products, from frozen foods and baked goods to confectionery and dried fruits, valued for its mild sweetness and stabilizing properties.

How Trehalose is Digested

For the body to absorb trehalose, it must first be broken down into two individual glucose molecules. This process is carried out by an enzyme called trehalase, which is located in the brush border of the small intestine. In most healthy individuals, this enzyme efficiently digests trehalose, and the resulting glucose is readily absorbed. The digestion rate of trehalose is slower than that of common table sugar (sucrose), which can result in a more gradual and sustained impact on blood glucose levels.

The Link Between Trehalose and Diarrhea

Diarrhea from trehalose is primarily linked to maldigestion, a condition where the sugar is not properly broken down and absorbed in the small intestine. When undigested trehalose continues its journey to the large intestine, it acts as an osmotically active substance, drawing water into the colon. This increased fluid volume in the bowel, combined with fermentation by gut bacteria, leads to the characteristic symptoms of osmotic diarrhea. This can happen for two main reasons.

Trehalase Deficiency

The most direct cause of trehalose-induced diarrhea is a rare, genetic metabolic condition known as trehalase deficiency, or isolated trehalose intolerance. Individuals with this condition have little to no functional trehalase enzyme in their small intestine. As a result, even small amounts of trehalose, such as those found in a serving of mushrooms, can trigger significant gastrointestinal distress, including abdominal pain, bloating, and diarrhea. While rare in most populations, this condition has a higher prevalence in certain groups, such as the Greenlandic Inuit.

High-Dose Trehalose Malabsorption

Even individuals with normal trehalase activity can experience malabsorption if they consume very large quantities of trehalose at once. Just as with other carbohydrates, there is a limit to how quickly the small intestine can process and absorb a sugar. A study found that the "transitory laxative threshold" for trehalose in healthy adults varied, but that some subjects experienced malabsorption and symptoms with doses as low as 25 grams. For perspective, that amount is roughly equivalent to what might be added to a large serving of certain processed foods. The resulting osmotic effect is similar to the cause of diarrhea from excessive consumption of sugar alcohols like sorbitol.

Digestive Symptoms of Trehalose Maldigestion

When trehalose is not properly absorbed, a number of gastrointestinal symptoms can arise from the fermentation process in the colon. These symptoms can range in severity depending on the individual's sensitivity and the dose consumed.

Osmotic Diarrhea: The defining symptom, caused by the influx of water into the colon.
Bloating and Distension: Caused by the gas produced by gut bacteria fermenting the undigested sugar.
Abdominal Pain and Cramping: The stretching of the intestinal walls due to gas and fluid accumulation leads to pain.
Flatulence: The release of gases such as hydrogen and methane, which are byproducts of bacterial fermentation.
Borborygmi: The audible rumbling of gas and fluid moving through the intestines.

Trehalase Deficiency vs. High-Dose Malabsorption


Feature	Trehalase Deficiency	High-Dose Malabsorption
Cause	Genetic inability to produce sufficient trehalase enzyme.	Exceeding the digestive capacity of a healthy person's trehalase.
Dose Required	Small amounts, often from naturally occurring sources like mushrooms, can trigger symptoms.	High doses, typically from additives in processed foods or supplements, are needed to cause issues.
Severity	Can be consistently severe with every exposure to trehalose.	Symptoms are usually temporary and disappear after the high dose is processed or excreted.
Prevalence	Rare in most populations, with a higher incidence in Greenland.	Occurs in anyone who over-consumes trehalose, regardless of ethnicity.

The Gut Microbiome and Trehalose

Research into trehalose's interaction with the gut microbiome has also attracted attention. While trehalose itself is broken down by the trehalase enzyme, some gut bacteria also possess the ability to metabolize it. This was brought into focus with a 2018 study linking a rise in hypervirulent strains of Clostridioides difficile (RT027 and RT078) to increased trehalose consumption. However, subsequent, more extensive research has questioned this causal link, suggesting that the trehalose-metabolizing traits in these bacteria were widespread before the increase in food additive use and that trehalose intake does not directly lead to worse outcomes in infections. In fact, some studies have even suggested trehalose can have beneficial prebiotic effects by promoting the growth of certain probiotic species.

Conclusion

While trehalose is a generally safe food additive approved by regulatory bodies, the question of whether it can cause diarrhea has a nuanced answer. For the vast majority of people, moderate consumption is unlikely to cause any issue due to the effective action of the trehalase enzyme. However, there are two important exceptions. Individuals with the rare genetic disorder trehalase deficiency will almost certainly experience gastrointestinal symptoms, including diarrhea, after consuming trehalose. Additionally, even healthy individuals can experience osmotic diarrhea if they consume a very high amount in a single sitting, overloading their digestive capacity. Therefore, for most, moderation is key, but those with a known intolerance should avoid it entirely. For more information, the National Institutes of Health (NIH) provides details on genetic conditions like trehalase deficiency and related research findings.

Frequently Asked Questions

Trehalase deficiency is a rare metabolic disorder where a person's small intestine does not produce enough of the enzyme trehalase to digest trehalose. This leads to malabsorption and symptoms like diarrhea after consuming trehalose.

Yes, even healthy individuals can experience diarrhea from trehalose if they consume a very large dose. The digestive system can be overwhelmed, leading to malabsorption and the osmotic effect that causes diarrhea.

The mechanism is osmotic diarrhea. When undigested trehalose reaches the colon, its high concentration draws water into the intestine. This, combined with fermentation by gut bacteria, results in loose stools and other symptoms.

Trehalose is found naturally in mushrooms, baker's yeast, algae, and some shellfish. It is also widely used as an additive in processed foods like baked goods, frozen desserts, and confectioneries.

Yes, the digestive consequences are similar. Both are caused by the lack of a specific digestive enzyme (trehalase vs. lactase) needed to break down a specific sugar. The resulting malabsorption leads to similar osmotic symptoms.

The amount varies by individual, but studies have shown that some healthy adults experience malabsorption at doses around 25 grams, while others tolerate up to 60 grams without issues. In highly processed foods, the concentration is usually low.

When malabsorption occurs, other symptoms besides diarrhea can include abdominal bloating, pain, cramping, and increased flatulence. In individuals with the deficiency, these symptoms are more pronounced and consistent.