The Role of the Trehalase Enzyme in Digestion
Trehalose is a disaccharide, or double sugar, made of two glucose molecules linked by a unique $\alpha,\alpha-1,1$ glycosidic bond. Unlike maltose, which is also a double glucose sugar but has a different bond, trehalose requires a specific enzyme for digestion. This enzyme, known as trehalase, is produced in the human body and is located at the brush border of the small intestine.
When trehalose is consumed, it travels to the small intestine, where trehalase gets to work. The trehalase enzyme cleaves the $\alpha,\alpha-1,1$ bond, breaking the trehalose molecule into two individual glucose molecules. These simpler, single glucose molecules are then readily absorbed by intestinal cells via sodium glucose transporter 1 (SGLT1) for use as energy. This process is efficient for the majority of the population, leading to full digestion of trehalose.
The Slower Digestion Advantage and Glycemic Response
The specific $\alpha,\alpha-1,1$ linkage in trehalose is more resistant to rapid hydrolysis compared to the bonds in other common disaccharides like sucrose or maltose. This slower digestive breakdown means that the release of glucose into the bloodstream is more gradual, resulting in a lower and more prolonged glycemic response.
This prolonged energy release is one of the reasons trehalose is marketed as a healthier sugar alternative. By avoiding the rapid spike and subsequent crash in blood sugar and insulin levels often associated with sucrose, trehalose provides a steadier supply of energy. This property makes it a potentially beneficial option for individuals looking to manage their blood sugar levels more effectively, though it still provides calories and should be consumed in moderation.
Understanding Trehalase Deficiency
While most people digest trehalose without issue, a rare genetic condition known as trehalase deficiency can hinder or prevent its proper breakdown. In affected individuals, there is a lower-than-normal level of functional trehalase enzyme in the small intestine due to a genetic mutation. This leads to trehalose intolerance, with symptoms appearing after consuming foods containing the sugar.
Symptoms of Trehalase Deficiency
When undigested trehalose passes into the large intestine, it is fermented by the gut microbiota. This fermentation process causes various gastrointestinal symptoms, including:
- Abdominal pain and cramps
- Osmotic diarrhea
- Increased rectal flatulence and bloating
- Vomiting (in some cases)
The condition is most prevalent in certain populations, notably affecting up to 8% of the population in Greenland due to an autosomal dominant inheritance pattern. For individuals diagnosed with trehalase deficiency, management involves avoiding foods that contain trehalose, such as mushrooms, and being mindful of it as an additive in processed foods.
Trehalose vs. Sucrose Digestion: A Comparison
| Feature | Trehalose (α,α-1,1 glucose) | Sucrose (glucose-fructose) |
|---|---|---|
| Enzyme for Digestion | Trehalase | Sucrase (part of sucrase-isomaltase complex) |
| Digestion Rate | Slower due to unique glycosidic bond | Faster due to less resistant glycosidic bond |
| Glycemic Impact | Lower and steadier blood sugar response | Higher and more rapid blood sugar spike |
| Component Sugars | Two glucose molecules | One glucose and one fructose molecule |
| Final Absorbed Product | Glucose only | Glucose and Fructose |
The Role of Trehalose in the Gut Microbiota
The gut microbiome plays a significant role in digestive health, and recent research has explored the relationship between trehalose and gut bacteria. Studies have found that trehalose can have prebiotic effects, promoting the growth of certain beneficial bacteria, such as specific strains of Lactococcus.
Interestingly, a 2018 study suggested a link between increased trehalose consumption and the virulence of certain strains of the pathogenic bacterium Clostridioides difficile (C. difficile). However, more recent and rigorous research has largely contradicted this initial correlation. For example, a 2021 study using a human gut model found that trehalose supplementation actually prevented simulated C. difficile infection and promoted the growth of nutritionally competitive microbiota. A subsequent meta-analysis also found no conclusive link between trehalose usage and C. difficile outbreaks. This highlights the importance of well-controlled studies to evaluate the effects of dietary changes on the gut microflora.
Where is Trehalose Found?
Trehalose is present in a variety of natural and processed foods:
- Mushrooms: A common natural source of trehalose.
- Baker's and Brewer's Yeast: Found in yeast and products containing it, such as bread.
- Seaweed: Some types of seaweed contain trehalose.
- Insects: Some insects use trehalose as a primary energy source.
- Processed Foods: Due to its functional properties as a stabilizer and sweetener, trehalose is used in many food products, including baked goods, confectionery, and frozen desserts. It is also added to dried food to improve its longevity and quality.
Can Trehalose be Digested by People with Celiac Disease?
According to research, trehalase activity may be temporarily affected by intestinal diseases like untreated celiac disease. In individuals with celiac disease, trehalase activity has been shown to be lower during periods of villous atrophy but can recover to normal levels on a gluten-free diet. This suggests that for many celiac patients who adhere to a strict gluten-free diet, trehalose digestion is not a long-term issue. However, individuals with celiac disease who are still experiencing intestinal damage may have reduced trehalase activity and could experience mild symptoms after consuming trehalose.
Conclusion
For the vast majority of healthy individuals, trehalose is fully digestible thanks to the enzyme trehalase in the small intestine. Its slow and steady breakdown into glucose provides a more gradual glycemic response compared to other common sugars, which is often seen as a health advantage. However, for the small percentage of the population with trehalase deficiency, this sugar can cause significant gastrointestinal discomfort. The relationship between trehalose and the gut microbiome is still being explored, with initial concerns about its impact on C. difficile being largely dispelled by more comprehensive studies. Ultimately, while moderation is key with any sugar, understanding how trehalose is metabolized can help inform dietary choices, especially for those with digestive sensitivities.
