What is Isomaltose?
Isomaltose is a disaccharide, or double sugar, that is naturally present in some fermented foods like sake and soy sauce and is also a breakdown product of starch. In the food industry, isomaltulose (also known by the trade name Palatinose) is the most common isomer of isomaltose used as a sugar alternative. Both isomaltose and isomaltulose are composed of glucose and fructose, but their unique chemical bonds mean they are digested and absorbed more slowly than sucrose (table sugar). This slow digestion provides a sustained energy release and a lower glycemic and insulinemic response, which is why isomaltulose is often marketed as a healthier sugar option.
Unlike isomaltulose, the substance known as isomalt is a sugar alcohol produced by hydrogenating isomaltulose. As a sugar alcohol, isomalt is known to be poorly absorbed and, when consumed in large quantities, can cause more direct gastrointestinal side effects like diarrhea. It is important to distinguish between isomaltose/isomaltulose and isomalt, as their effects on the body are different. The primary focus of the side effects related to isomaltose in its natural or isomaltulose form relates to how it is handled by the digestive system.
Digestive Side Effects in Healthy Individuals
For most healthy individuals, isomaltose, particularly in the form of isomaltulose, is generally well-tolerated, even at doses of up to 50 grams. However, its slow-digesting nature means that consuming large quantities can sometimes lead to gastrointestinal distress. When digestion is delayed, the unabsorbed sugar travels further down the small intestine and into the large intestine, where it can be fermented by gut bacteria. This fermentation process can lead to common digestive symptoms such as:
- Abdominal bloating and distention
- Excess gas (flatulence)
- Stomach cramps
- Diarrhea
These symptoms are typically mild and dose-dependent. A person unaccustomed to consuming large amounts of slowly digestible carbohydrates is more likely to experience these effects. As the gut adapts to increased intake, the symptoms may subside. The side effects are similar to those seen with other fermentable carbohydrates known as FODMAPs, though isomaltulose is generally not considered a high-FODMAP food in typical serving sizes.
Isomaltose and Specific Intolerances
While isomaltose is largely safe for the general population, it can cause severe adverse reactions in individuals with specific genetic or metabolic disorders. These conditions directly impact the body's ability to process this type of sugar.
Congenital Sucrase-Isomaltase Deficiency (CSID)
This is a rare genetic disorder where individuals have a deficient or absent sucrase-isomaltase enzyme in their small intestine. Since this enzyme complex is responsible for breaking down isomaltose (and sucrose), those with CSID cannot properly digest it. This results in significant symptoms, especially after consuming sucrose or starches, and is often diagnosed in infancy. The undigested sugars act as an osmotic laxative and are fermented by bacteria, leading to more pronounced gastrointestinal symptoms, including:
- Chronic, watery diarrhea
- Severe abdominal cramps and bloating
- Nausea and vomiting
- Failure to thrive (in infants)
Hereditary Fructose Intolerance
Because isomaltose breaks down into glucose and fructose, individuals with hereditary fructose intolerance (HFI) are advised to avoid it. HFI is a serious genetic disorder where the body lacks an enzyme needed to metabolize fructose. Consuming isomaltose could lead to severe health issues in these individuals, including hypoglycemia (low blood sugar) and liver damage.
Comparing Isomaltulose and Sucrose Digestion and Side Effects
| Feature | Isomaltulose (Palatinose™) | Sucrose (Table Sugar) |
|---|---|---|
| Digestion Rate | Slow and gradual | Fast and rapid |
| Glycemic Response | Low GI (approx. 32) | High GI (approx. 67) |
| Insulin Response | Lower and slower | Higher and faster |
| Gastrointestinal Side Effects | Possible with large doses due to slow transit | Less likely in healthy individuals due to rapid absorption |
| Impact on Gut Microbiota | Modulates composition, may increase beneficial bacteria | Can feed pathogenic bacteria when in excess, potentially causing imbalance |
| Dental Health | Non-cariogenic, does not promote tooth decay | Highly cariogenic, contributes to tooth decay |
| Caloric Value | 4 kcal/g, same as sucrose | 4 kcal/g, same as isomaltulose |
Isomaltulose and Gut Microbiota Modulation
Beyond the potential for mild distress with overconsumption, there is research to suggest that isomaltulose and isomalto-oligosaccharides (IMO), a type of carbohydrate containing isomaltose, may have beneficial effects on the gut microbiome. As slowly digested carbohydrates, they can serve as a prebiotic, feeding beneficial bacteria in the colon. Studies in rats have shown that isomaltulose increases the abundance of beneficial bacteria like Faecalibacterium while decreasing pathogens. This process can lead to an increase in beneficial short-chain fatty acids like propionate and butyrate, which are important for gut and overall health. For most people, this modulation of gut bacteria is considered a positive effect, not a negative side effect, although the fermentation process itself can cause gas and bloating.
Conclusion
For the average person without specific intolerances, the side effects of isomaltose are minimal and generally related to consuming an excess amount, which can cause temporary digestive discomfort. The most significant risks are associated with underlying genetic conditions like Congenital Sucrase-Isomaltase Deficiency or Hereditary Fructose Intolerance, where isomaltose digestion is impaired. Isomaltulose is a safer and potentially healthier alternative to sucrose for managing blood sugar levels, and its slow digestion may offer prebiotic benefits to the gut. However, those with known sensitivities or who are new to consuming isomaltose or related products should start with small quantities to assess their tolerance. For individuals with CSID or HFI, complete avoidance is necessary. When evaluating any sugar alternative, including isomaltose, it is always wise to listen to your body and consult a healthcare professional for personalized dietary advice. You can find more information about these and other carbohydrates on the NIH website, which provides comprehensive medical genetics resources.
Visit MedlinePlus for more on Sucrase-Isomaltase Deficiency
Navigating Isomaltose for Health-Conscious Consumers
This low-glycemic sugar offers a sustained energy release and is tooth-friendly. Digestive side effects are mainly an issue for those with specific genetic disorders or with excessive consumption. The slow digestion of isomaltulose can beneficially modulate gut bacteria, promoting prebiotic effects. It is crucial to distinguish between isomaltose, isomaltulose, and isomalt, which is a sugar alcohol with different side effects. For individuals with CSID or hereditary fructose intolerance, isomaltose and isomaltulose must be strictly avoided. Testing tolerance with small amounts is recommended for healthy individuals new to this sugar substitute.
Managing Potential Discomfort
If you experience digestive discomfort, reduce the amount of isomaltose consumed. Staying hydrated can also help mitigate symptoms of gastrointestinal upset. For those with severe or persistent symptoms, a doctor's evaluation is important to rule out underlying conditions. Gradually increasing intake allows the gut microbiome to adapt, which may reduce future discomfort.
Sources of Isomaltose
Isomaltose is present in honey and is created from the digestion of starch, but isomaltulose is the common food additive. Check product labels for “isomaltulose,” “Palatinose,” or “isomalt” to identify its presence. Isomaltulose can be found in various products like energy drinks, protein bars, confectionery, and baked goods.
Consulting a Professional
When considering major dietary changes or experiencing persistent symptoms, consulting a healthcare professional is best. A registered dietitian can provide personalized advice and help integrate or limit isomaltose based on individual needs and health conditions. A doctor's diagnosis is critical for managing genetic intolerances like CSID.
Isomaltose and Exercise
For athletes, isomaltose can provide a sustained energy supply during exercise, helping to prevent hypoglycemia. Studies show it improves blood glucose control during moderate exercise in people with type 1 diabetes when used with adjusted insulin. This prolonged energy release is a major benefit, though excessive consumption can still lead to stomach issues during intense activity.
The Low GI Advantage
Compared to sucrose, isomaltose has a significantly lower glycemic index, causing a lower and more gradual rise in blood sugar. This low GI property is beneficial for people managing diabetes or weight. The European Food Safety Authority (EFSA) and FDA have approved related health claims regarding isomaltulose's low glycemic response.
Who Should Avoid Isomaltose
Individuals with CSID or hereditary fructose intolerance must avoid isomaltose. Anyone with a sensitive digestive system, such as those with IBS, should approach consumption with caution and test their personal tolerance levels. Starting with very small portions is key to preventing digestive upset.
