What foods have non-digestive carbohydrates? Your Guide to Fiber and Resistant Starch

October 29, 2025 •

5 min read

Less than 10% of American adults consume the recommended daily amount of fiber, a key form of non-digestive carbohydrates. These essential components, which include both dietary fiber and resistant starch, are not broken down by your body's digestive enzymes but instead feed beneficial gut bacteria.

Quick Summary

This article explores non-digestive carbohydrates (NDCs), detailing key food sources like whole grains, legumes, fruits, and vegetables. It explains the different types of NDCs and their specific health benefits for digestion, blood sugar, and overall wellness.

Key Points

Sources of NDCs: Legumes, whole grains (especially cooked and cooled), vegetables like potatoes and garlic, and fruits like unripe bananas contain non-digestive carbohydrates.
Two main types: The two primary non-digestive carbohydrates are dietary fiber (soluble and insoluble) and resistant starch.
Health benefits: NDCs improve digestive health, support a healthy gut microbiome, help regulate blood sugar levels, and can lower cholesterol.
Prebiotic effect: Many NDCs act as prebiotics, which serve as food for the beneficial bacteria in your large intestine.
Cooking methods matter: The amount of resistant starch in foods like rice and potatoes can be increased by cooking and then cooling them.
Focus on variety: A balanced intake from a mix of plant-based sources—fruits, vegetables, legumes, and whole grains—is recommended for optimal benefits.

What Exactly Are Non-Digestive Carbohydrates?

Non-digestive carbohydrates (NDCs) are a complex group of dietary substances that are not absorbed in the small intestine but instead pass into the large intestine, where they are fermented by gut bacteria. The most well-known NDCs are dietary fiber and resistant starch, though they have different properties and sources. Unlike simple carbs that spike blood sugar, NDCs have a gradual or non-existent effect on glucose levels, making them a crucial part of a healthy diet.

The Two Main Types: Fiber and Resistant Starch

Dietary fiber is traditionally split into two categories based on its solubility in water:

Soluble Fiber: This type dissolves in water to form a gel-like substance in the digestive tract. This gel slows down digestion, helping to lower blood cholesterol and stabilize blood sugar levels. It also ferments in the colon, acting as a prebiotic that feeds good bacteria.
Insoluble Fiber: As the name suggests, this fiber does not dissolve in water. It adds bulk to the stool and helps food pass more quickly through the digestive system, promoting regular bowel movements and preventing constipation.

Resistant starch (RS) is a type of starch that, as the name implies, resists digestion in the small intestine. It is not always classified as traditional fiber, but it functions similarly by acting as a prebiotic in the colon. There are several types of resistant starch, including:

Type 1 (RS1): Found in whole grains, seeds, and legumes, this starch is physically inaccessible to enzymes due to the cell walls.
Type 2 (RS2): Found in certain raw foods like raw potatoes and green bananas, where the starch is tightly packed.
Type 3 (RS3): Formed when starchy foods like potatoes, rice, and pasta are cooked and then cooled. This process, called retrogradation, makes the starch more resistant to digestion.

A List of Foods with Non-Digestive Carbohydrates

To increase your intake of these beneficial carbs, focus on incorporating a wide variety of plant-based foods into your diet. Most fibrous foods contain a mix of soluble and insoluble fiber.

Legumes, Beans, and Lentils

This group is a powerhouse of both fiber and resistant starch, making it one of the best sources of NDCs.

Black beans: Rich in fiber and provide resistant starch.
Lentils: A great source of both soluble and insoluble fiber.
Chickpeas: Versatile and packed with fiber.
White beans: Particularly high in resistant starch.
Split peas: An excellent source of dietary fiber.

Whole Grains

Moving beyond refined flour products is a simple way to boost your NDC intake.

Oats: Especially rolled oats and oat bran, are high in soluble fiber, specifically beta-glucans. Try overnight oats for added resistant starch.
Barley: Another great source of beta-glucans.
Brown Rice and Quinoa: Unlike their white counterparts, these whole grains retain their fiber content.
Whole-wheat products: Breads and pastas made with whole-wheat flour contain more fiber.

Vegetables

Many vegetables contribute both fiber and prebiotic compounds like inulin.

Artichokes and Jerusalem artichokes: Rich sources of inulin.
Onions, garlic, and leeks: These all contain fructans, including inulin.
Cruciferous vegetables: Broccoli, brussels sprouts, and cauliflower all provide good amounts of fiber.
Potatoes (especially cooked and cooled): When cooked and then cooled, potatoes develop resistant starch.
Carrots: Provide a healthy dose of fiber.

Fruits

Fruits are a delicious way to add fiber, particularly if you eat the skins or seeds.

Green (unripe) bananas: Contain resistant starch that converts to sugar as they ripen.
Berries: Loaded with fiber, especially with the tiny seeds they contain.
Apples and pears (with skin): The skin is where a significant amount of the insoluble fiber is found.
Avocado: Provides fiber and healthy fats.

Nuts and Seeds

These are excellent sources of both soluble and insoluble fiber.

Chia seeds: A well-known source of soluble fiber.
Flaxseed: Contains both soluble and insoluble fiber.
Almonds and walnuts: Provide a mix of fiber and healthy fats.

Health Benefits of Non-Digestive Carbohydrates

Beyond simply aiding digestion, NDCs play several critical roles in maintaining overall health.

Supports a Healthy Gut Microbiome: NDCs act as prebiotics, which are food for the beneficial bacteria in your large intestine. This promotes a balanced gut ecosystem, which is linked to a stronger immune system and improved mental health.
Improves Blood Sugar Control: By slowing down the absorption of carbohydrates, soluble fibers and resistant starches prevent sharp spikes in blood glucose, making them especially beneficial for managing diabetes.
Lowers Cholesterol Levels: Soluble fiber binds with cholesterol particles in the digestive tract, carrying them out of the body before they can be absorbed. This can help lower LDL ('bad') cholesterol.
Promotes Satiety and Weight Management: Because they slow down gastric emptying, NDCs help you feel fuller for longer, which can lead to reduced overall calorie intake and support weight control.
Enhances Digestive Regularity: Insoluble fiber is particularly effective at adding bulk to stool, which promotes regular bowel movements and can help prevent or relieve constipation.

Comparison of Non-Digestible Carbohydrate Types


Feature	Soluble Fiber	Insoluble Fiber	Resistant Starch	Prebiotics (e.g., Inulin)
Effect on Water	Dissolves and forms a gel.	Does not dissolve.	Can act like soluble or insoluble fiber.	Soluble and fermentable.
Primary Function	Slows digestion, lowers cholesterol and blood sugar.	Adds bulk to stool, promotes regularity.	Feeds good gut bacteria, improves gut health.	Supports beneficial gut bacteria growth.
Digestion Site	Fermented in the large intestine.	Passes largely intact through the digestive tract.	Fermented in the large intestine.	Fermented in the large intestine.
Common Sources	Oats, barley, nuts, seeds, beans, lentils, apples, citrus fruits.	Whole-wheat products, wheat bran, vegetables, nuts.	Green bananas, cooked and cooled potatoes, rice, pasta, legumes.	Chicory root, garlic, onions, asparagus, bananas.

Practical Tips for Boosting Non-Digestive Carbs

Incorporating more NDCs doesn't have to be complicated. Here are some simple strategies:

Embrace the chill: Cook and then cool starchy foods like potatoes, rice, and pasta before eating. This increases their resistant starch content. Reheating does not destroy this newly formed resistant starch.
Make smart swaps: Choose whole-grain bread and pasta over refined versions. Opt for brown rice instead of white.
Add legumes to your meals: Toss lentils or chickpeas into salads, soups, and stews.
Power up your breakfast: Start your day with a bowl of oatmeal or make overnight oats.
Don't peel your fruits and veggies: Keep the skin on apples, pears, and potatoes for an extra fiber boost.
Experiment with flours: Try using chickpea flour or other alternative flours when cooking.
Snack smarter: Reach for fresh fruits, nuts, and seeds instead of processed snacks.

By diversifying your diet with these various sources, you can ensure a broad range of benefits for your digestive health and beyond. The health-promoting effects are highly dependent on the type of NDC, so aiming for a mix from different food groups is the best approach.

Conclusion

Non-digestive carbohydrates, encompassing dietary fiber and resistant starch, are far more than just 'roughage.' They are a crucial, health-promoting component of a balanced diet, offering benefits that range from improving gut health and blood sugar control to assisting with weight management and lowering cholesterol. By focusing on a diet rich in whole foods—including legumes, whole grains, a wide variety of fruits, and vegetables—you can easily boost your intake of these essential carbs. Making mindful choices, such as preparing and cooling starchy foods or choosing whole grains over refined options, allows you to harness the full potential of these powerful nutrients. For more information on dietary guidelines, consult the National Institutes of Health.

Frequently Asked Questions

Regular carbohydrates, or digestible carbs, are broken down by enzymes in the small intestine into glucose, which is used for energy. Non-digestive carbohydrates, like fiber and resistant starch, pass through the small intestine largely intact and are fermented by bacteria in the large intestine, where they provide other health benefits.

Resistant starch is a specific type of non-digestive carbohydrate that functions like fiber but is not always classified as traditional dietary fiber. It is a type of starch that resists digestion in the small intestine and is fermented in the large intestine, acting as a prebiotic.

Cooking can increase or decrease the resistant starch content in food, depending on the process. For example, cooking and then cooling starchy foods like rice, potatoes, and pasta creates retrograded starch (RS3), which is more resistant to digestion.

In the large intestine, non-digestive carbohydrates are fermented by beneficial bacteria, acting as a food source or 'prebiotic'. This process promotes the growth of good bacteria, which is essential for a healthy gut microbiome and overall digestive function.

Yes, increasing your intake of non-digestive carbs can aid in weight management. The fiber content helps you feel fuller for longer by slowing down digestion, which can lead to reduced overall calorie intake throughout the day.

Soluble fiber, found in foods like oats, beans, apples, and nuts, is particularly effective at lowering cholesterol. It forms a gel in the digestive tract that binds to cholesterol and helps carry it out of the body.

While highly beneficial, excessive intake of non-digestive carbs can lead to gastrointestinal symptoms such as bloating, gas, and cramping, especially when increasing intake too quickly. It is best to increase fiber intake gradually and ensure adequate water consumption.