Soluble Corn Fiber

Fact-checked by Dr. Anthony Gustin, DC, MS.

Written by Sheila Amir

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Soluble corn fiber may sound fairly harmless. Or, hearing the word fiber, you might even think it’s good for you.

You’d be wrong. Dietary fiber — found mostly in vegetables, fruit, legumes, and grains — is known for relieving constipation, normalizing bowel movements, lowering your cholesterol levels, building gut bacteria diversity, and helping you maintain a healthy weight.

This isn’t the case with soluble corn fiber. Let’s dig into the facts and learn why you might want to avoid this highly processed additive.

Here’s what you’ll learn:

Is Soluble Corn Fiber Part of a Keto Diet?

What Is Soluble Corn Fiber?

Soluble corn fiber (SCF) is a non-digestible fiber you’ll find in many processed foods, from cookies and crackers to soups and salad dressings.

Soluble corn fiber, also known as maltodextrin and resistant maltodextrin, is used as a thickener, filler, and preservative in many packaged foods.
Processed food manufacturers love SCF because it’s a cheap way to bulk up products, thicken soups, sauces, and dressings, and increase shelf life.

Is Soluble Corn Fiber a “True Fiber?”

From a chemist’s perspective? Yes, SCF looks and maybe even acts like the fiber you’ll find fruits and veggies. It’s even categorized as a fiber on nutrition labels.

However, fiber should never spike your blood glucose levels, and SCF will. Let’s look at the role of fiber in your body and see why SCF shouldn’t make the cut with other high-fiber foods.

Fiber comes in a couple of different forms, but all fiber is non-digestible.

Non-digestible simply means that these compounds bypass your small intestine and ferment in your large intenstine[*]. This isn’t a bad thing. In fact, that’s what all resistant starches do, and resistant starches have benefits like:[*]

Forms of fiber include:

      • Soluble fiber. Soluble fiber is water-soluble. That means it creates a viscous gel in your digestive tract that moves slowly through your system. Soluble fiber can improve blood glucose control, which can reduce heart disease and improve cholesterol levels.
      • Insoluble fiber. Insoluble fiber doesn’t dissolve in water and makes your stool softer and easier to pass. It also improves your insulin response and is associated with lower cholesterol.
      • Prebiotic fiber. Also known as resistant starches, these can be soluble or insoluble. Prebiotics also pass through your system undigested, but they stay in your large intestine and ferment, creating a more diverse gut microbiome.

All fiber is known for a few health benefits like:

      • Reducing insulin resistance and improving your insulin repsonse[*]
      • Promoting colon health[*]
      • Burning body fat[*]
      • Improving sleep[*]

Soluble corn fiber, regardless of its name, can act more like a prebiotic fiber in your gut, which is why some studies claim it has some health benefits.

But there’s a reason you want resistant starch from natural sources like potatoes and not from soluble corn fiber: SCF isn’t actually food.

How Is Soluble Corn Fiber Made?

Soluble corn fiber isn’t something you’ll find in nature. It starts with corn syrup, which is already chemically processed. The corn syrup is heated, then broken down even further through a process called enzymatic hydrolysis.
Enzymes break down the syrup into a non-digestible, low sugar fiber which is then filtered several times into a tasteless white powder.

The good news is, SCF is around 25 on the glycemic index, which is pretty low, compared to white table sugar, which clocks in at 100[*].

The bad news is, it may still kick you out of ketosis and cause some digestive upset. Plus, SCF is about as processed as it gets.

Are There Health Benefits to Soluble Corn Fiber?

Health benefits? Not really.

Unless you count that it’s super cheap for food manufacturers to thicken and preserve processed foods.

Some other arguments you might see for the “benefits” could include:

      • It has a lower glycemic response than sugar (yay?)
      • It may act as a prebiotic, which can help increase beneficial gut bacteria in your large intestine; mostly bifidobacteria, Bacteroides, Butyricicoccus, Dialister, and Oscillibacter[*]
      • One study in postmenopausal women showed an increase in bone calcium retention after supplementing with SCF. This is likely because an increase in beneficial bacteria is associated with better calcium absorption, but again, you can get this from better quality sources.

That’s pretty much it. Especially if you’re on a keto diet.

Other arguments for SCF include those for athletes or people with hyperglycemia who need quick and easy spikes in blood sugar for performance reasons.

But if you’re keto and running off of fat, that’s never going to be an issue.

There are even more arguments that, because SCF is digestion-resistant (acts as a resitant starch), it’s good for overall gut health. However, there are much more natural prebiotic sources that don’t originate from GMO corn syrup.

Plus, as you’ll read below, more data suggests SCF is bad for your gut bugs. So, it’s best to stay away.

Is Soluble Corn Fiber Safe?

From a biochemical standpoint, soluble corn starch is technically safe to consume in small amounts. In fact, the studies above showed some positive physiological responses to the resistant starch properties of SCL.

But it’s highly processed, which means you may have some adverse reactions, including digestive upset, bloating, and gas.

Plus, who wants lab-created compounds in their food when you could get the same benefits from natural fiber sources?

If you want fiber, get it from more natural sources like vegetables and a small amount of low-sugar fruits.

Other keto-friendly foods with high fiber content include:

      • Avocado
      • Broccoli
      • Cauliflower
      • Eggplant
      • Zucchini
      • Coconut meat

Other adverse effects of soluble corn fiber:

      • It can spike your blood glucose and kick you out of ketosis. This is tricky when it comes to packaged foods because it’s listed as “fiber” and throws off the number of net carbs[*]. In other words, it’s listed as fiber, but fiber won’t spike blood sugar. SCF will.
      • It can mess with your gut bacteria. While some data supports SCF as a decent prebiotic, studies on maltodextrin (SCF’s other name) contradict that. Maltodextrin may suppress the proliferation of beneficial bacteria like bifidobacteria and increase the number of harmful bacteria in your digestive tract[*].  Changes like this can make you more susceptible to gut dysbiosis and can severely lower immune function.
      • It can make you gain weight. Even with a lower score on the glycemic index than some sweeteners, it’s still a carbohydrate with zero nutritional value, and it will increase your blood sugar. That’s a definite recipe for fat storage.
      • It’s probably made from genetically modified corn. Unless the product is labeled “organic,” it’s highly likely your SCF is made from GMO corn. If that’s something you want to avoid, stay away from SCF and maltodextrin.

Is Soluble Corn Fiber Part of a Keto Diet?

You could argue that soluble corn fiber is a cheap source of calories that’s a bit lower on the glycemic index than other sweeteners and additives.

But it will likely spike blood glucose levels and kick you out of ketosis.

Here’s what to use instead:

      • If you’re concerned about your fiber intake and digestive health, stick to natural sources.
      • If you’re looking to balance blood sugar, make sure you’re in ketosis and get your energy from plenty of healthy sources of fatty acids.
      • Looking to gain weight? Stick to a keto diet and up your calorie intake.
      • Concerned about calcium absorption and bone health? Again, natural sources of prebiotic foods, plus adding more calcium-rich foods to your diet like grass-fed dairy products and leafy greens will help.
      • Better sweeteners include stevia and monk fruit. And more natural thickeners include ingredients like pectin and guar gum.

Soluble corn fiber won’t kill you. But it definitely won’t make you stronger.

The consensus is: avoid soluble corn fiber when you can.

There’s no reason to add this to your diet. And if you read “soluble corn fiber,” “maltodextrin,” or “resistant maltodextrin” on a package, it’s probably best to put it back on the shelf.

UP NEXT: Fixing Your Gut Health And The Truth About Fiber Intake and Bacteria

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