Isomalto-oligosaccharides, commonly abbreviated as IMO, has been a popular ingredient in the food industry for several years, frequently used in protein bars, sugar-free syrups, and other supposedly 'healthy' snacks. Its low-calorie and high-fiber marketing pitch has attracted a loyal following among those on low-carb or keto diets. However, the reality of this functional carbohydrate is more complex than it appears on the packaging.
What is IMO, and is it a Sugar?
To answer the question, "Is IMO a type of sugar?", we must first understand its chemical structure. IMO is not a monosaccharide (a single sugar unit like glucose) or a disaccharide (two units, like sucrose). Instead, it is a mixture of short-chain carbohydrates, or oligosaccharides, made up of several glucose units linked together. The links are predominantly alpha-(1-6) glycosidic bonds, which are resistant to digestion in the human small intestine, unlike the easily broken alpha-(1-4) bonds found in starch. This digestion-resistant property is what initially gave IMO its reputation as a fiber.
Natural vs. Industrial IMO
It is important to differentiate between naturally occurring IMO and the industrially produced version. Naturally, IMO is found in small quantities in fermented foods like miso, sake, and soy sauce, and also in honey. The commercial IMO used in processed foods is manufactured from starch, often from corn, tapioca, or peas, through an enzymatic process. The composition of commercial IMO can vary significantly depending on the production method. The final product contains a mixture of oligosaccharides, along with a small but non-negligible percentage of simpler, easily digestible sugars like glucose and isomaltose. A 2016 application to Health Canada showed commercial IMO preparations containing greater than 90% oligosaccharides and isomaltose, with less than 5% glucose. However, the ratio of digestible to non-digestible components can fluctuate, with some lower-purity versions having a much higher proportion of simple sugars.
The Surprising Truth About Blood Sugar Impact
While industrial IMO is marketed as a fiber and low-glycemic ingredient, multiple studies have revealed a different story. The 2018 study mentioned in the introduction demonstrated that IMO consumption resulted in a significant increase in both blood glucose and insulin, similar to what would be expected from a digestible carbohydrate. This robust glycemic response suggests that a substantial portion of the ingested IMO is indeed being absorbed and metabolized by the body, rather than passing through undigested as a fiber should. A separate investigation in the Journal of Food Science in 2017 similarly concluded that the glycemic impact of industrial IMO ingredients was inconsistent with how products containing them were being labeled. This creates a major problem for diabetics or individuals on low-carb diets who rely on food labels and marketing claims to manage their blood sugar levels.
The Fiber Controversy and Labeling Issues
The U.S. Food and Drug Administration (FDA) has addressed the labeling concerns surrounding IMO. The FDA's definition of dietary fiber requires a non-digestible carbohydrate to also demonstrate a beneficial physiological effect on human health, such as lowering cholesterol or improving blood glucose response. The FDA has rejected petitions from some IMO manufacturers, determining that the specific industrial IMOs in question did not meet the criteria to be labeled as dietary fiber. This regulatory position directly contradicts the marketing claims many brands have made, potentially misleading consumers.
Potential for Digestive Distress
Like many digestion-resistant carbohydrates, consuming large amounts of IMO can lead to gastrointestinal issues. When the undigested portion reaches the large intestine, it is fermented by gut bacteria, which can cause symptoms such as bloating, gas, and abdominal discomfort. The maximum permissible dose varies by region and source, but excessive intake is consistently linked to these side effects.
IMO vs. Sucrose (Table Sugar)
To further clarify the nutritional profile of IMO, comparing it to standard table sugar (sucrose) is helpful.
| Feature | IMO (Industrial) | Sucrose (Table Sugar) |
|---|---|---|
| Chemical Type | Oligosaccharide (mixture of glucose units) | Disaccharide (1 glucose + 1 fructose unit) |
| Glycemic Impact | Can cause significant blood glucose and insulin spikes | Causes a rapid spike in blood glucose and insulin |
| Sweetness Level | Approx. 50-70% as sweet as sugar | Standard reference for sweetness (100%) |
| Caloric Content | Marketed as lower calorie (approx. 2.4 kcal/g) | High calorie (approx. 4.0 kcal/g) |
| Fiber Content | Can function as prebiotic fiber in the large intestine | Zero fiber content |
Final Verdict: Is IMO Just Another Sugar?
While IMO is not a simple sugar, labeling it a fiber is often misleading for the consumer. Its significant impact on blood glucose, particularly for certain industrial varieties, means it cannot be considered a truly low-glycemic sweetener. It provides a sweet taste with fewer calories than sugar and offers some prebiotic benefits, but it also carries potential for digestive side effects and mislabeling. For individuals carefully managing blood sugar, reading labels and understanding the potential glycemic impact is crucial. For further information on its composition and regulatory status, health authorities provide detailed reports, such as this one from Health Canada on the approval of a specific IMO product. Ultimately, IMO is a functional carbohydrate with unique properties, but it is not a perfect, zero-impact sugar replacement.
Conclusion
In conclusion, IMO is a carbohydrate mixture, not a simple sugar. Its effectiveness as a low-calorie, low-glycemic sweetener is highly dependent on its specific composition and can be misleading, especially for those monitoring blood sugar. While it does offer prebiotic benefits, consumers should be aware of the potential for blood glucose spikes and digestive issues. The ongoing regulatory scrutiny and varying quality of industrial IMO products necessitate careful consideration by consumers when choosing purportedly 'sugar-free' or 'low-carb' products containing this ingredient.
