Is Soluble Corn Fiber Keto?

If you’ve read our nutrition label lately, you might have noticed soluble corn fiber listed on the packaging. 

Perhaps this made you concerned. Corn is a grain, after all. Aren’t grains banned on most healthy diets, keto included?

Not necessarily. Because it’s a form of dietary fiber, corn fiber isn’t digested like a normal carbohydrate. It passes through your gut, and gets digested by gut bacteria instead.

Does this make soluble corn fiber keto?

Most likely, yes. But you’ll have to read on for the full explanation. 

In this article, you’ll learn everything you need to know about soluble corn fiber: basics, benefits, keto-friendliness and potential side effects. Okay, time to learn. 

What Is Soluble Corn Fiber?

Soluble corn fiber is a form of dietary fiber—or plant material that can’t be broken down by human digestive enzymes. Specifically, soluble corn fiber is a type of fiber known as a low-digestible carbohydrate

Corn fiber is typically used to add fiber and texture and a little sweetness to packaged goods. It’s a low-calorie, low-glycemic sugar alternative.  

When you eat corn fiber, it passes largely undigested through your gut. First it goes through the stomach, then through the small intestine, then into the large intestine. In the large intestine, your gut bacteria digest this fiber, creating beneficial byproducts. More on this later. 

In case you were wondering, soluble corn fiber is made by isolating starch from corn syrup and using natural enzymes to convert these starches into non-digestible fiber. These fibers are called prebiotics because they feed good bacteria in the gut.

In fact, most soluble fiber is prebiotic fiber. Not all fiber, however, is soluble fiber.    

Soluble Fiber vs. Insoluble Fiber

monte cristo sandwich

There are two main classes of dietary fiber: soluble fiber and insoluble fiber. Soluble, by the way, simply means “able to dissolve in water”.

Most soluble fibers (like soluble corn fiber) pass through the gut and are digested in the colon by your gut microbiota. That’s why most soluble fiber is considered prebiotic, or fementable, fiber. It feeds gut bacteria. 

Insoluble fiber, on the other hand, does not typically feed your gut bacteria. Instead it passes through the entire gut largely intact, adding bulk to stool and regularity to bowel movements. 

Both soluble and insoluble fiber can be beneficial, but we’ll be focusing on soluble fiber benefits today. These benefits include enhanced intestinal health, better blood sugar control, and lower inflammation. Let’s turn to soluble corn fiber now, and see what researchers have found. 

Benefits of Soluble Corn Fiber

Is soluble corn fiber good for you? Consider the following benefits and decide for yourself. 

#1: Gut health

Think of dietary fiber as nourishment for gut bacteria. You digest normal food, they digest fiber. 

When gut bacteria ferment fiber, they produce anti-inflammatory short chain fatty acids like butyrate, propionate, and acetate. These compounds not only fuel your colon cells, but they also reduce inflammation (unnecessary immune activity) throughout your body. 

Some evidence suggests that corn fiber improves your gut environment. In one randomized trial, 14 days of soluble corn fiber supplementation increased the levels of bifidobacteria (a beneficial strain of gut microbe) in healthy volunteers.

#2: Blood sugar stability 

banana caramel keto

Keeping blood sugar low is the key to entering the fat-burning state known as ketosis. That’s why the keto diet requires strict carb restriction. Less carbs, lower blood sugar. 

Does eating corn fiber spike blood sugar? It appears not. In one 2018 study, researchers found that a soluble corn fiber supplement did not raise blood sugar significantly more than a placebo. Good news for keto folks. 

Basically, soluble corn fiber is used to reduce sugar in many products while still giving you the flavor and texture that you love.

#3: Immune health

More and more, scientists are exploring the deep link between gut health and the immune system. Believe it or not, about 70% of your immune cells are located in the gut!

Fiber may strengthen this gut-immunity link. One group of researchers, for instance, gave older adults a soluble corn fiber supplement along with a probiotic (or beneficial bacteria strain) for three weeks. The result? Enhanced immune function, as measured by increased natural killer cell activity. 

#4: Bone health 

working out strong bones

In adolescent females, one month of soluble corn fiber supplementation (12 grams per day) improved calcium absorption. Higher calcium absorption, as a rule, correlates with better bone density. 

Researchers speculate that two types of bacteria—Parabacteroides and Clostridium—were involved. Soluble corn fiber nourishes these microbes, which in turn help shuttle calcium through the gut and into the bloodstream for building bone.  

Soluble Corn Fiber Side Effects and Concerns 

Most corn plants in America are genetically modified organisms, or GMOs. This usually means the corn has been bred to resist herbicides like Roundup.  

Roundup, unfortunately, contains a potentially carcinogenic compound called glyphosate. And while it’s not clear that conventional soluble corn fiber contains this toxin, it’s probably best to play it safe and stick with a non-GMO soluble corn fiber. (FYI: That’s one of the reasons we only use non-GMO soluble corn fiber in our products!).

Along with the concern about GMOs, eating too much corn fiber (any fiber, really) has the potential to cause gas, bloating, indigestion, diarrhea, or other forms of GI distress. In general, however, the small amounts of soluble corn fiber in packaged foods should be well-tolerated.

Choosing Keto-Friendly Fibers

The quality and sugar content of soluble corn fiber varies widely by product. Some corn fibers are as high as 40% sugar, while others (like the kind used at Keto and Co) are restricted to 4% sugar fiber. This is a HUGE difference if you’re trying to stay keto.

What about tapioca fiber? It’s often promoted as a healthy alternative to soluble corn fiber, but in reality: Tapioca fiber has more sugar! A lot of manufacturers, however, use tapioca fiber so they can label their products “grain free”, even though it’s a bigger sugar hit. 

Two quick tips to make sure you’re staying healthy and keto-friendly:

  1. Choose foods from a brand that you trust and that specializes in keto
  2. Look for a company that lists net carbs to the decimal point 

Follow these tips and you’ll be well prepared to ace your keto shopping trip. 

Is Soluble Corn Fiber Healthy?

old fashion donuts

In short, yes: Non-GMO soluble corn fiber is a healthy addition to your keto lifestyle. 

To keep your memory fresh, here’s a quick recap of what you just learned about soluble corn fiber:

  • Soluble corn fiber is an indigestible carbohydrate that feeds your gut bacteria. 
  • There are two types of fiber: soluble and insoluble. Soluble fiber feeds gut bacteria, while insoluble fiber generally passes through the gut intact.  
  • Soluble corn fiber doesn’t appear to impact blood sugar. In other words, it’s keto-friendly!
  • Fiber supports a healthy gut, which translates to a healthier immune system. 
  • Soluble corn fiber may increase calcium absorption in young women.
  • Favor non-GMO soluble corn fiber to avoid potential brushes with toxins. 

So all things considered, you can rest easy next time you see soluble corn fiber on a nutrition label.

Author: Brian Stanton

Bio: Brian Stanton is the author of Keto Intermittent Fasting, a certified health coach, and an expert in the keto diet, fasting, and gut health. Follow Brian’s work by visiting his website at

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