Soluble corn fiber may sound reasonably harmless. Upon hearing the word “fiber,” you might even think it’s good for you.
Dietary fiber — found mostly in vegetables, fruit, legumes, and grains — is known for relieving constipation, normalizing bowel movements, lowering cholesterol levels, building microbiota diversity, helping you maintain a healthy weight, and promoting satiety[*].
However, this isn’t the case when it comes to soluble corn fiber (SFC). In this article, you’ll learn all about this ingredient and why you should avoid it.
Soluble corn fiber is a non-digestible fiber in many processed foods, from cookies and crackers to soups, protein bars, and salad dressings.
SCF, 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 and thicken soups, sauces, and dressings while increasing the product’s shelf life.
From a chemist’s perspective, SCF looks and maybe even acts like the fiber you find in fruits and veggies. It’s even categorized as fiber on nutrition labels.
However, fiber should never spike your blood glucose levels — SCF does.
Take a closer 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, meaning that these compounds bypass your small intestine and ferment in your large intestine[*].
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 stools softer and more comfortable to pass. It can also improve 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, along with probiotics.
All fiber is known for a few health benefits:
- It can help to reduce insulin resistance and improve your insulin response[*].
- It promotes colon health[*].
- It might boost fat burning[*].
- It can help to improve 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 health benefits.
But there’s a reason why you should prefer resistant starch, which comes from natural sources like potatoes and not from soluble corn fiber: SCF isn’t actually food.
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 can cause some digestive upset.
Due to its highly processed nature, soluble corn fiber doesn’t provide any health benefits. Despite this, it’s commonly used by food manufacturers as a cheap addition to thicken and preserve processed foods.
Some other arguments you might see for the “benefits” include:
- It has a lower glycemic response than sugar.
- A crossover study conducted on older healthy adults found that, when combined with probiotics, soluble corn fiber can help reduce the risk of cardiovascular diseases[*].
- It may act as a prebiotic, which can help increase beneficial gut bacteria in your large intestine — mostly bifidobacteria, Bacteroides, Butyricicoccus, Dialister, and Oscillibacter. It can also help in laxation[*].
- One study conducted in postmenopausal women showed an increase in bone calcium retention after supplementing with SCF. This is likely due to an increase in beneficial bacteria, which is associated with better calcium absorption, but again, you can get this from better quality sources[*].
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 in ketosis and using fat as your primary energy source, that won’t be an issue.
Plus, more data suggests SCF can be harmful to your gut bacteria.
From a biochemical standpoint, soluble corn starch is technically safe to consume in small amounts. The aforementioned studies show some positive physiological responses to the resistant starch properties of SCL.
However, it’s highly processed, which means you may have some adverse reactions, including digestive upset, bloating, and gas[*].
You’ll want to be getting the same benefits from natural fiber sources, instead of ingesting lab-created compounds which have been added to your food.
If you want fiber, opt for more natural sources like vegetables and a small amount of low-sugar fruits.
Other keto-friendly foods with high-fiber content include:
- 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. Therefore, if you have type 2 diabetes, be extra careful as it can be a hidden ingredient.
- It can mess with your gut bacteria. While some data support 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 your immune function[*].
- It’s probably GMO. Unless the product is labeled as organic, it’s highly likely your SCF is made from GMO corn.
Soluble Corn Fiber and the Keto Diet
You could argue that soluble corn fiber is a cheap source of calories that ranks a bit lower on the glycemic index than other sweeteners and additives.
But it can spike your 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 fiber sources.
- If you’re looking to balance blood sugar, make sure you’re in ketosis and get your energy from healthy sources of fatty acids.
- If you’re concerned about calcium absorption and bone health, opt for natural sources of prebiotic foods and consider adding more calcium-rich foods to your diet like grass-fed dairy products and leafy greens.
- Choose keto-friendly sweeteners such as stevia or monk fruit. Natural thickeners include ingredients like pectin and guar gum.
Soluble corn fiber has no real nutritional value and can be replaced by healthier options. Since it’s commonly used in the food industry, reading ingredient labels is vital to ensure you’re not accidentally ingesting this highly-processed additive.
If you read “soluble corn fiber,” “maltodextrin,” or “resistant maltodextrin” on a package, put it back on the shelf.
To learn more about digestion, fiber, and keto, consider reading these articles: