Trehalose is a fascinating disaccharide found in various organisms, celebrated for its ability to protect cells from environmental stress. However, as with any food additive or dietary supplement, a balanced perspective requires a look at the potential downsides. For many, trehalose is well-tolerated, but for some, particularly when consumed in high doses, there are notable drawbacks to consider, from digestive discomfort to more complex health controversies.
The Trehalose and C. difficile Controversy
One of the most publicized disadvantages of trehalose emerged from a 2018 study published in Nature, which suggested a link between increased trehalose consumption and the rise of particularly virulent strains of Clostridioides difficile (C. difficile). The study, based on laboratory and animal experiments, found that certain hyper-virulent strains of C. difficile could thrive on low doses of trehalose, potentially giving them a competitive advantage in the gut microbiome. This research led to sensationalized media reports and significant public concern regarding the safety of trehalose as a food additive.
However, later research and epidemiological reviews have largely refuted this direct link, pointing out critical flaws in the original study's conclusions. Later analyses showed that the increase in commercial trehalose use often postdated the emergence of these hyper-virulent C. difficile strains in some regions, such as Canada and the US. Furthermore, other studies found no significant correlation between trehalose consumption levels and the incidence of C. difficile infections. The broader scientific consensus now suggests that the alarm over trehalose's role in the C. difficile epidemic was likely unwarranted and based on a misunderstanding of complex ecological factors. Despite the scientific backtracking, the initial media panic means this controversy remains a well-known, though contested, disadvantage associated with trehalose.
Incomplete Digestion and Gastrointestinal Issues
For a small percentage of the population, consuming trehalose can lead to classic symptoms of carbohydrate malabsorption, such as bloating, abdominal pain, and diarrhea. Trehalose is broken down into two glucose molecules by the enzyme trehalase in the small intestine. A rare genetic condition, particularly common in some populations like those in Greenland, results in a deficiency of this enzyme. For these individuals, consuming trehalose can cause significant gastrointestinal distress.
Even in people with normal trehalase activity, excessive intake of trehalose can overwhelm the digestive system's capacity to break it down, leading to similar symptoms. The undigested sugar passes into the large intestine, where it is fermented by gut bacteria, producing gas and potentially leading to osmotic diarrhea. This is a key reason why clinical studies often use moderate doses of trehalose to avoid these side effects.
Caloric Content and Weight Gain
Unlike non-nutritive sweeteners, trehalose is a sugar that provides calories—approximately 4 kcal per gram, identical to sucrose and other digestible carbohydrates. While its slower absorption rate and lower glycemic index are often cited as health benefits, this does not make it a calorie-free alternative for weight management. Overconsumption of any caloric sugar, including trehalose, can contribute to excess calorie intake and potential weight gain. For individuals on a ketogenic or low-sugar diet, the caloric contribution of trehalose is a significant disadvantage to monitor.
Comparison: Trehalose vs. Other Sugars
Understanding the drawbacks of trehalose is best done in comparison with other common sugars. While trehalose has a lower glycemic index, its caloric content and taste profile present different considerations.
| Feature | Trehalose | Sucrose (Table Sugar) | High-Fructose Corn Syrup | Caloric Sweeteners | Non-Nutritive Sweeteners |
|---|---|---|---|---|---|
| Glycemic Index | Relatively low (around 72) | High | High | Varies | Zero |
| Sweetness Level | About 45% as sweet as sucrose | Standard (100%) | Very sweet | Varies | Can be much sweeter |
| Caloric Density | 4 kcal/g | 4 kcal/g | 4 kcal/g | Varies | Zero |
| Risk of Bloating/Gas | Possible, especially with high intake or deficiency | Low in normal doses | Possible with high intake | Varies | Possible with certain types (e.g., sugar alcohols) |
| C. difficile Link | Controversial, now largely disproven epidemiologically | No known link | No known link | No known link | No known link |
| Cost | Can be more expensive than standard sugars | Inexpensive | Inexpensive | Varies | Can be expensive |
Cost and Production Considerations
Trehalose was considered a "novel food" in many regions, including Australia/NZ and Canada, because its use was expected to increase significantly beyond traditional dietary sources. While production methods have become more efficient, the cost of trehalose remains a factor compared to common, inexpensive sweeteners like sucrose or high-fructose corn syrup. The industrial synthesis of trehalose, while advancing, can still suffer from low yields and elevated costs, which can limit its widespread application in certain food products.
Side Effects in Other Applications
While this article primarily focuses on dietary disadvantages, it is worth noting other applications. For example, trehalose is used in eye drops to treat dry eye syndrome. In this context, some individuals have reported side effects such as temporary eye irritation, burning, redness, or blurred vision. Though not a disadvantage of oral intake, it highlights that even in non-dietary uses, trehalose can have specific adverse reactions for sensitive individuals.
Conclusion
While trehalose offers several interesting properties, including a lower glycemic index and potential cellular protection, it is not without its disadvantages. The once-alarming link to virulent C. difficile strains has been largely discredited by subsequent studies, but it serves as a cautionary tale about potential unintended consequences of novel food additives and the impact of sensationalized media. For most people, trehalose in moderation is safe. However, individuals with trehalase deficiency or those consuming large amounts may experience uncomfortable digestive side effects. Furthermore, its caloric content means it is not a zero-calorie sugar alternative, which is a disadvantage for those managing their weight. As always, it is wise to be aware of the full spectrum of effects when introducing any new ingredient into your diet.
For more detailed information on trehalose safety, refer to authoritative sources such as the Food and Drug Administration (FDA) and comprehensive reviews like the one linked here from a food ingredients manufacturer: Is Trehalose Safe?
