Top 25 Insoluble Fiber Foods

Fiber is described as “dietary material containing compounds resistant to the action of digestive enzymes, such as cellulose, lignin, and pectin.” Fiber, in other words, is a carbohydrate found in plants that are not digested in the stomach or intestines but instead goes through the gastrointestinal system and becomes part of feces.


According to the Dietary Guidelines for Americans, adults should aim for 14 grams of total fiber per 1,000 calories consumed. Unfortunately, the typical American eats just about half of the required amount of dietary fiber on most days, owing to a diet high in processed foods and refined grains and a lack of vegetables, fruits, legumes, and other fruits and vegetables.

Why is it so essential to consume foods that are rich in fiber? Each kind of fiber, insoluble and soluble, has its own set of advantages. For example, insoluble fiber helps to avoid constipation, cleanses the GI tract, and even protects against significant issues such as colon cancer.

What is Insoluble Fiber?

Dietary fiber is divided into two categories:

  • Insoluble fiber is a fiber that does not dissolve in water and remains undigested. Insoluble fiber may help food travel more quickly through the stomach and intestine. It may also help treat constipation by adding bulk to the stool.
  • In the colon, soluble fiber dissolves in water, holds water, and produces a gel-like material. As a result, it makes digestion and nutrition absorption in the stomach and intestine more difficult.

What foods have a lot of insoluble fiber? Wheat bran, various vegetables, nuts and seeds, potatoes, fruit with skin, legumes, and whole grains are just a few examples. Insoluble fibers come in multiple forms, including cellulose and lignin fibers, which may be found in various foods.

Health Advantages

1. Aids in the prevention and treatment of constipation

One of the significant functions of insoluble fiber is to produce bulk and form stool in the intestines, resulting in regular bowel movements and reduced constipation. Because insoluble fiber does not dissolve in water like soluble fiber, it aids in the direction of material through the colon by bulking up stools.

2. Carbohydrate/Sugar Absorption Is Slowed

While fiber is included in carbohydrate meals, it does not boost blood sugar levels; rather, it aids in slowing sugar absorption from carbohydrates, which is helpful for blood sugar control.

Other metabolic and health advantages of a diet rich in both forms of fiber include protection against obesity, cardiovascular disease, diabetes, and metabolic syndrome.

3. Can Aid with Weight Management and Appetite Control

High-fiber foods include insoluble fiber, which may help you feel full and content between meals. On the other hand, Insoluble fiber is not technically a calorie source since it is not digested and stays intact after consumption.

4. May aid in the prevention of GI problems 

Insoluble fiber aids in transporting and processing waste in the digestive tract, which is beneficial for bowel regularity. It may also help avoid constipation-related gastrointestinal obstructions and straining, leading to hemorrhoids.

Insoluble fiber also aids in the absorption and removal of byproducts and carcinogens from the gut, reducing the risk of SIBO, diverticulosis, and other digestive issues.

4. May Reduce Your Chances of Getting Colorectal Cancer

According to research, a greater overall dietary fiber consumption has been linked to a considerably lower risk of colorectal cancer. Entire cereal grains and whole pieces of fruit, both strong in insoluble fiber, have been demonstrated to be particularly protective against colon cancer development.

Increased fiber intake is thought to have anti-cancer benefits because it reduces fecal carcinogens, reduces transit time, and causes bacterial fermentation of fiber to short-chain fatty acids with anticarcinogenic characteristics.

Is insoluble Fiber beneficial to people with IBS? This is dependent on the kind of IBS a person has, their own dietary “triggers,” and their symptoms, such as whether they have diarrhea or constipation more often.

Insoluble vs. Soluble Fiber

Soluble vs. insoluble fiber: what’s the difference? Do you need soluble, insoluble, or both types of fiber?

Many foods include both soluble and insoluble fiber. Both forms of fiber have been demonstrated to aid with hunger control, weight management, digestion, bowel motions, cholesterol balancing, and other health benefits.

Soluble fiber’s role is to form a gel in the digestive tract. It aids in the binding of fatty acids, which is helpful to cholesterol levels and heart health. Soluble fiber also delays stomach emptying, improving nutritional absorption, satisfaction after eating, and appetite management. Soluble fiber may also assist in controlling blood sugar levels, reducing the risk of disorders such as insulin resistance and diabetes.

Beans, lentils, oats, barley, berries, and other vegetables are high in soluble fiber, and many of these foods also include insoluble fiber.

Soluble or insoluble fiber, which is better for constipation?

Although both forms of fiber may help you remain regular and avoid digestive difficulties, insoluble fiber is typically superior for preventing constipation.

Insoluble fiber does not ferment in the gut, but soluble fiber ferments in the stomach, causing bloating and gas. When bacteria digest soluble fiber in the large intestine, gas is released, which might result in a lot of flatulence if you eat a high-fiber diet. On the other hand, insoluble fiber stays intact as it travels through the GI system, which helps with constipation and reduces gas production.

This is why, depending on the individual, a high-fiber diet may occasionally aggravate IBS symptoms. Because everyone responds differently to different fiber-containing foods, it’s crucial to gradually include these items into your diet while also drinking lots of water.

Perhaps you’re curious about the types of fiber found in some of your favorite meals. Consider the following examples:

  • Oat bran, barley, almonds, seeds, beans, lentils, peas, and various fruits and vegetables contain soluble fiber.
  • Is the fiber in bananas soluble or insoluble? A banana contains around 2–3 grams of fiber, most of which is insoluble fiber, but both forms are present.
  • Is rice fiber soluble or insoluble? About 3–4 grams of fiber per cup of brown rice, about all of which is insoluble.
  • Is the fiber in spinach and lettuce soluble or insoluble? Insoluble fiber is abundant in dark leafy greens. For example, cooked spinach has around 6 grams of fiber, including about 5 grams of insoluble fiber.

Top 25 Foods High in Insoluble Fiber

Some of the best insoluble fiber foods are listed below:

  1. A wheat germ with wheat bran
  2. Oat bran
  3. Beans, lentils, and other legumes (kidney, black, garbanzo, edamame, split peas, lima, navy, white)
  4. Blackberries, blueberries, raspberries, strawberries, and other berries
  5. Barley, quinoa, sorghum, millet, amaranth, oatmeal, and rye are whole grains
  6. Turnips
  7. Peas, green
  8. Okra
  9. Spinach
  10. Radishes
  11. Rutabaga
  12. Coconut (grated flakes or flour)
  13. Cocoa
  14. Skinned apples
  15. Skinned pears
  16. Flaxseeds
  17. Avocado
  18. Sunflower seeds are a kind of sunflower
  19. Sweet potatoes with potatoes
  20. Apricots, prunes, raisins, dates, and figs that have been dried
  21. Almonds
  22. Walnuts
  23. Pasta and bread made entirely of whole grains
  24. Passionfruit
  25. Popcorn

Dosage and Supplement Options

How much insoluble fiber should you consume daily? Total fiber, rather than simply insoluble fiber, is presently suggested as a daily intake. For people 50 years and younger, the recommended total fiber intake (soluble and insoluble combined) is 38 grams per day for males and 25 grams per day for women.

Adults over 50 may get indigestion if they consume too much fiber, so a daily fiber intake of 30 grams for men and 20 to 25 grams for women is suggested; however, consuming more isn’t always a bad thing if it doesn’t create problems.

The total grams per serving, not simply grams of insoluble fiber, are generally included on food labels. This might make it difficult to determine how much of each kind of fiber you’re ingesting; however, rather than concentrating too much on the numbers, the primary objective should be to consume a variety of high-fiber meals.

While whole foods are the best source of fiber, fiber supplements are an alternative for persons who might benefit from even more insoluble fiber to help avoid constipation. Fiber is collected from natural sources, such as psyllium husk, to provide a concentrated dosage in supplement form. Because each fiber product has various potencies, start with a smaller dosage and gradually increase it as required while also drinking lots of water.

If you’re suffering from diarrhea, remember that a soluble fiber supplement is preferable to an insoluble fiber supplement.

Side Effects and Risks

Is insoluble FFiber ever harmful to your health? If you’re prone to diarrhea or loose stools, such as inflammatory bowel disease or IBS, consuming a lot of insoluble fiber might make you feel uncomfortable and increase your symptoms. If you have celiac disease or are gluten intolerant, proceed with care while improving your insoluble fiber consumption.

If you adjust your diet to include more foods rich in insoluble fiber and have loose stools or other GI problems, it’s a good idea to reduce the quantity of fiber you’re eating and see your doctor for guidance. You could also want to try an elimination diet to figure out whether high-fiber or FODMAP items are causing you problems.

When eating a high-fiber diet, it’s also essential to drink enough water since water aids Fiber’s function.

Frequently Asked Questions

What food is highest in insoluble fiber?

A: The highest in insoluble fiber food are vegetables like broccoli, spinach, and cucumbers.

Are bananas soluble or insoluble fiber?

A: Bananas are soluble fiber.

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