In most cases, if you grab a low-carb snack at random from the grocery store shelf and look at the label, a common nutrient profile contains around 20 grams of carbohydrates, yet maybe 15 of those grams are from “fiber.” The result is five grams of net carbs, right? Not so fast. . . if a Type I diabetic were to consume that bar, cookie, or brownie with the five grams of net carbs, there should not be a need for insulin since, theoretically, there is minimal glucose (blood sugar) entering the system from those five net carbs, which shouldn’t require an insulin response. Unfortunately, theory and outcome do not always match.
The increased awareness regarding the importance of fiber, in addition to its distinct metabolic effects, has resulted in a surge of companies switching to an alternative fiber known as soluble corn fiber (SCF). Interestingly, SCF has been available on the US market since 2007 and is used in foods and beverages across the Americas, Europe, and Southeast Asia. SCF is produced through an extensive process: corn syrup is exposed to a suite of enzymes for at least 48 hours, some of which are found in the brush border of your small intestine, as well as the pancreas.[5] Notably, a large majority of the corn syrup contains easily digestible carbohydrates; however, a small portion is, in fact, not digestible. At the end of this enzymatic exposure, a stream of digestion-resistant carbohydrates remains and is subsequently filtered several times. The resulting product is a “true fiber” that contains a mixture of α-1,6, α-1,4, α-1,2, and α-1,3 glucosidic linkages, which, as mentioned above, contribute to its low digestibility. 

There are two general categories of dietary fiber: soluble and insoluble. Fibrous foods typically contain both soluble and insoluble fibers. As a society, we understand the importance of fiber, including the benefits related to lowering body fat, decreasing the prevalence of diabetes, improving insulin sensitivity, decreasing the risk of heart disease and increasing satiety, as well as the beneficial bacteria in our digestive system.[1] Unfortunately, less than 5% of Americans actually meet the 30 gram per day recommended intake. To help increase fiber consumption, an increasing number of companies have developed a host of delicious, low-carb, high-fiber treats. Despite this, it is important to understand how our bodies process two of the most common “fibers” on the market that are used in these treats: isomaltooligosaccharides (IMOs) and soluble corn fiber (SCF).
After I had spent some time thinking about it and reading the labels on every brand of eggnog at Walmart, I decided to try my hand at making my homemade keto eggnog. I won’t lie, I am an eggnog snob, and I have tasted lots of different brands and homemade versions over the year. My favorite brand is Southern Comfort Eggnog, and I have never tasted homemade eggnog that I enjoyed. That’s why I decided not to get excited about this little experiment. I plan to make five different eggnog recipes, and this was my first attempt. I tasted this recipe immediately after making it, and I wasn’t very impressed. Like many eggnogs, I have tried in the past it was bland and didn’t taste like my favorite brand.
We’ve all seen it on food labels: “Only 2 net carbs” or “Low net carbs.” But what does this truly mean? What are net carbs, and why does it matter? Are all net carbs created equal, or are we stretching those claims a bit too much? After reading through this article, I think you will agree that there is a pressing need to educate on the precise definition of net carbs, and what exactly constitutes a true fiber.

One of the first studies to examine IMO syrups[2] had six subjects consume 25 grams of IMO syrup. These researchers found that glucose levels increased from 109 mg/dL pre-ingestion to a peak of 136 mg/dL 30 min post-ingestion. Additionally, insulin rose to nearly parallel levels with that of glucose from 4.8 μU/mL pre-ingestion to nearly 32 μU/mL at 30 min post-ingestion. These values clearly indicate that some digestion is occurring. Furthermore, these researchers found that IMO was about 83% as digestible as maltose under resting conditions and about 69% as digestible after the exercise period. Taken together, this suggests that a large majority of the carbohydrate in the IMO syrup was, in fact, digested, absorbed, and metabolized.
Lastly, one of the advertised benefits of IMO is possible prebiotic activity. Prebiotics are critical, as they feed the beneficial bacteria in our digestive system, specifically in the large intestine. These bacteria have several amazing functions, such as lowering body fat, improving insulin sensitivity, and lowering depression. Two “gold standard” prebiotics in the industry are inulin and fructooligosaccharides (FOS). Inulin and FOS are non-digestible carbohydrates that robustly increase beneficial bacteria. The challenge, however, is that both inulin and FOS, due to their rapid digestibility by intestinal bacteria, result in low gastric tolerance, and, ultimately, gastric distress. Additionally, inulin and FOS, when added to protein bars or other goods, may degrade over time into individual sugar units. Regardless, one study comparing inulin to IMOs, found that the prebiotic activity in inulin is 14 times greater than that of IMOs.[4] This is logical because, as you recall from above, approximately 70% to 90% of IMOs are digested. As such, only a small portion of these prebiotic fibers make it to the large intestine, in which two out of three studies have demonstrated that this small portion may indeed have some prebiotic effects.