Connect two glucose molecules, and you get a food additive that offers surprising health benefits. Trehalose is a common ingredient in eye drops, but its potential uses range from diabetes to fatal nerve diseases. The media recently suggested that trehalose is to blame for the rise in resistant superbugs – but is that really so? Read on to learn all the perks and dangers of trehalose.
What Is Trehalose?
Two molecules of glucose build trehalose, also known as tremalose or mycose. Bacteria, plants, fungi, and insects use it as an energy source and a guard against extreme conditions.
Trehalose enables some species to survive up to 99% dehydration and complete freezing. Insects also use it as flight fuel because it releases 2 molecules of glucose and gives twice as much energy [R, R+].
The food industry recognized these unique properties of trehalose and introduced it as an additive in dried and frozen foods. For this purpose, they make trehalose from corn starch.
Did you know? Trehalose is a secret weapon of the “resurrection plant” (S. lepidophylla), which can survive months of complete drought.
Some microbes use trehalose to make toxins and defensive weapons. For example, Mycobacterium tuberculosis protects its cell with trehalose-6’6-dimycolate (TDM), which triggers inflammation and lung damage in humans [R, R].
Is Trehalose a Reducing Sugar?
No, it’s not. In trehalose, 2 reducing groups of glucose form a (1,1-glycosidic) bond and thus lose their reducing properties. This bond makes trehalose resistant to harsh changes in temperature and acidity [R].
Sucrose, or common table sugar, is also a non-reducing sugar.
On the other hand, reducing sugars like dextrose, lactose, and maltose are less stable. They increase browning and caramelization in the presence of protein (such as those from eggs or dairy) during baking.
Foods and Products with Trehalose
Mushrooms, shrimps, and algae contain small amounts of trehalose, followed by certain seeds, honey, and baked products.
Trehalose binds water, prevents oxidation, and preserves the structure of food during freezing and heating. It also improves the taste while causing slightly milder blood glucose spikes. These properties made trehalose a common food additive in [R, R, R]:
- Dried and frozen food
- Instant food (noodles, rice, soups)
- Sugar coatings and fillings
- Baked goods
Most manufacturers label trehalose under “added sugars” or “natural flavors.”
Trehalose Medical Uses
Trehalose can bind water and retain moisture, which makes trehalose eye drops a popular choice for dry eye. Skin care products, quick-dissolving tablets, and some advanced biological drugs also contain trehalose [R, R, R, R].
Besides its physical properties used in technology, trehalose may have essential health benefits.
Snapshots of Trehalose
- Provides energy
- Boosts cardiovascular health
- May protect the brain and nerves
- May prevent diabetes
- Not well studied in humans
- May increase the risk of gut infections
- Some people don’t tolerate it
- Comes with other drawbacks of simple sugars
Trehalose Health Benefits
How It Works
Autophagy is a vital defensive mechanism that removes mutated and damaged cells. The lack of autophagy lurks behind metabolic disorders, brain damage, cancer, aging, infections, and more. Trehalose may boost autophagy, which makes it a promising drug candidate [R].
As you’re about to see in “Trehalose Dangers and Side Effects”, its impact on our gut bacteria also has its dark side.
1) Eye Care
Trehalose eye drops protected rabbits from UV-induced eye damage by blocking oxidative stress. Cell experiments confirmed the ability of trehalose to prevent drying, strengthen the cells, and combat UV damage [R, R, R, R].
2) Boosts Cardiovascular Health
In 32 healthy adults, trehalose (100 g daily for 12 weeks) relaxed blood vessels and improved their function by 30%, which may cut the risk of major cardiovascular diseases. Trehalose probably achieved this by raising nitric oxide levels [R].
That said, 100 g of trehalose (sugar) delivers ~400kcal and it’s not the healthiest addition to one’s diet. The researchers noted that some patients struggled to maintain their body weight.
Trehalose induced autophagy in blood vessel cells and inhibited a virus linked to clogged blood vessels (the human cytomegalovirus or HCMV) [R].
Health Benefits with Limited Evidence
Clinical trials haven’t confirmed the following health benefits of trehalose.
3) Protects the Brain and Nerves
- Stimulated autophagy
- Reduced protein mutations and brain inflammation
- Raised the levels of protective proteins: progranulin and BDNF
- Improved symptoms
- Increased survival
Amyotrophic lateral sclerosis (ALS) is a fatal disease that attacks motor neurons and eventually leads to total paralysis. Doctors are still looking for ALS causes and cures [R+].
In mice with ALS, trehalose prevented the accumulation of harmful proteins and induced autophagy in motor neurons. As a result, it slowed down disease progression and extended the animals’ lifespan [R, R, R].
Trehalose may shield against fetal nerve damage caused by mother’s diabetes. In the embryos of diabetic mice, trehalose induced autophagy and prevented neural tube defects [R].
4) May Prevent Diabetes
In diabetic rats, a combination of guava juice and trehalose [R]:
- Boosted glucose tolerance (OGTT) and metabolism
- Relieved oxidative damage
- Protected the pancreas and kidneys
Tests on 20 volunteers confirmed that trehalose causes a milder increase in blood glucose (38%) and insulin (36%), compared with an equal amount of glucose. Fat accumulation was also lower [R].
The glycemic index of trehalose – how much it spikes glucose levels compared to sugar – is still debated. The above study suggests it’s index is surprisingly low (38) while other studies indicate it’s borderline high (~70) [R, R].
All in all, trehalose might help prevent diabetes or reduce complications. But clinical studies would need to evaluate its effectiveness and safety as a sweetener in diabetic patients.
5) May Help with Fatty Liver
Trehalose boosted autophagy and prevented further fat buildup in the liver in mice with fatty liver. A cell study verified these effects and found that trehalose blocks glucose transport in the liver [R, R].
6) May Protect the Stomach
Aspirin is a well-known trigger of stomach ulcers, despite modern formulations that may bypass the stomach [R].
Scientists have developed a new formulation of aspirin with trehalose that’s gentler for the stomach. In rats, it prevented ulcers and damage to the stomach lining while maintaining the desired effects [R].
Trehalose in Skin Care
7) May Shield Against UV Damage and Skin Cancer
In test tubes, trehalose induced autophagy in skin tissue. This effect prevented the spreading of cancer cells and protected healthy cells against UV damage. The results make trehalose a promising candidate for sunscreen lotions and other cosmetic products [R].
Trehalose Dangers & Side Effects
Safety studies found no trehalose dangers in pregnancy and childhood. They suggest limiting the intake of trehalose to 50 g daily, or 10% of total calories [R].
But is there another side of the trehalose coin?
Trehalose and the C. Diff. Epidemic
Indeed, a study recently published in Nature suggests that the use of trehalose as a food additive may have triggered the uncontrolled growth of aggressive, antibiotic-resistant superbugs.
Trehalose may stimulate the growth of Clostridium difficile (C. diff.), a germ that causes dangerous, hard-to-treat gut infections. In mice infected with certain strains of C. diff., trehalose increased the death rate 3 times. These strains thrived on trehalose and produced much more toxins [R, R].
Although these findings echoed loudly in the media, they are far from conclusive. Before pressing the panic button, we should consider the following facts [R]:
- So far, only one animal study showed this effect on a small sample (55 mice)
- Trehalose boosted only a few mutated strains of C. diff.
- “Outbreaks” of C. diff infections are mostly limited to hospitals and caused by other strains, which don’t seem to thrive on trehalose
And, after all, trehalose is a sugar; our gut quickly breaks it into 2 glucose molecules. Just like with other simple sugars, you may want to go slow with trehalose.
While it may be a good idea to swap glucose for trehalose, avoid adding it on top of your daily sugar intake. People with diabetes and insulin resistance should pay extra attention.
How to Avoid Trehalose
A small percentage of people lack trehalase, an enzyme that breaks down trehalose. This leads to trehalose intolerance, in which foods with trehalose cause digestive issues. It is common among the Inuits from Greenland (approx. 8%) but rare around the globe [R].
If you suspect trehalose intolerance, you may want to avoid mushrooms, seafood, dried and frozen foods. You already avoid insects, right? (pun intended)
For a complete list, see “Foods and Products With Trehalose.” The lack of strict labeling regulation makes trehalose a bit harder to avoid.
But there might be a solution to this issue.
A popular probiotic yeast, S. boulardii, releases trehalase in the gut. S. boulardii increased gut trehalase activity by 25 – 45% in mice. In a cell experiment, this enzyme was 175 times more active than a human form [R].
Limitations and Caveats
Research on the health benefits of consuming trehalose is promising, but the data are scarce. With only 1 placebo-controlled clinical trial (32 patients), we can’t conclude much about its effects in humans [R].
The fact that some people don’t tolerate trehalose also limits its potential applications.
When it comes to cosmetics, low skin permeability of trehalose is a big drawback. Modern formulations with liposomes (tiny lipid particles) may overcome this issue [R].
The Verdict: Is Trehalose Safe or Dangerous?
In light of the available evidence, trehalose remains safe for healthy people in doses up to 50 g a day. People with diabetes and insulin sensitivity should pay special attention to their daily sugar intake, which includes trehalose.
To stay on the safe side, avoid trehalose if you have any digestive issues, especially hospital-acquired gut infections.
Trehalose is a non-reducing sugar with 2 glucose molecules (disaccharide). Microbes, plants, fungi, and insects use it as a source of energy and protection against extreme conditions. It shields the cells from freezing and dehydration.
Mushrooms, seafood, seeds, and baked products contain small amounts of trehalose. The food industry adds it to dried and frozen food; candy and fruit fillings; chocolate and juices.
In medicine, trehalose is used in eye drops and advanced drug formulations. Trehalose eye drops can help with dry eye.
Trehalose stimulates autophagy, a vital cell repair process that prevents damage and mutations. It may thus protect nerves, the heart, and blood vessels, but the evidence is limited. Trehalose may also shield the skin against UV damage and mutations. It’s commonly added to skin care products.
Safety studies found no adverse effects of trehalose in adults, children, and pregnant women. To stay on the safe side, limit the intake to 50 g daily, or 10% of total calories.
Some people are trehalose-intolerant because they lack trehalase, an enzyme that breaks it down. They should avoid foods and products with trehalose. Supplementing with a probiotic yeast, S. boulardii, may increase trehalase in the gut.