Foods With Soluble vs. Insoluble Fiber

Soluble fiber and insoluble fiber are the two types of fiber. Both are important for health, but each performs a different role within your body. Soluble fiber helps you slow down digestion and control cholesterol and blood sugar levels. Insoluble fiber adds bulk to your stool and helps you keep your bowel movements regular.

This article discusses the differences between soluble and insoluble fiber, their respective health benefits and food sources, and how much fiber you should include in your diet each day.

Person cutting banana into a bowl of fruits, cereal, and yogurt


Differences Between Soluble and Insoluble Fiber

Fiber is a beneficial part of your diet. Though both soluble and insoluble fiber are important, each type of fiber acts differently in the digestive tract and provides different health benefits. Here is what makes each unique.

Absorption in Digestive Tract 

Soluble fiber dissolves in water and forms a gel-like substance after you consume it. It also helps slow down digestion, which can aid in blood sugar control. 

Insoluble fiber does not dissolve in water. It remains mostly whole as it passes through your digestive tract. This adds bulk to your stool, helping you keep your digestive tract healthy and bowel movements regular.


Fiber has been studied for its many and various health benefits. Some are specific to soluble or insoluble fiber, while other health benefits are attributed to dietary fiber in general. 

Soluble fiber is known for helping to manage cholesterol levels and lowering the risk of heart disease. Some studies also show that soluble fiber may improve symptoms of diarrhea in irritable bowel syndrome (IBS).

Both types of fiber are beneficial for people with diabetes. Research has proved that soluble fiber can aid in blood sugar control. It has also proved that insoluble fiber can support insulin sensitivity (the body's response to insulin, a hormone that allows cells to take in glucose to convert to energy).

Dietary fiber may also: 

High-Fiber Diet for Certain Health Conditions

A high-fiber diet is a commonly recommended treatment for digestive problems such as constipation, diarrhea, and hemorrhoids. It may also be recommended for people with certain health conditions with GI symptoms (i.e. constipation), such as IBS, inflammatory bowel disease (IBD), diabetes, multiple sclerosis, and bowel endometriosis

Individual results will vary, and the scientific evidence supporting these recommendations is mixed. Always talk with your healthcare provider before changing your diet, especially if you have a health condition.

Sources of Fiber

Fiber is found in plants. Many plants contain both types of fiber. However, the amounts vary depending on the plant, and some have more of one type than the other. Below are some good sources of soluble and insoluble fiber.


Sources of soluble fiber include:

  • Apples
  • Bananas
  • Oats
  • Barley
  • Peas
  • Black beans
  • Lima beans
  • Brussels sprouts
  • Psyllium (a common fiber supplement)


Sources of insoluble fiber include:

  • Whole wheat flour
  • Wheat bran
  • Nuts
  • Seeds
  • Beans, peas, and lentils
  • Berries
  • Spinach
  • Avocado
  • Cauliflower
  • Popcorn
  • Skins of many fruits and vegetables

Nutrition Labels 

Nutrition labels on food products do not usually say which type of fiber is in the food because ​reporting soluble and insoluble fiber is not required, though it may be voluntarily reported. 

You can find a food product's overall dietary fiber amount by looking at the nutrition facts label. Because fiber is a form of carbohydrate, it is grouped with and listed below total carbohydrates. 

"Dietary fiber" on the nutrition facts label includes naturally occurring fibers from plants and certain isolated or synthetic non-digestible carbohydrates added to food that the Food and Drug Administration (FDA) has determined to have beneficial physiological effects on human health.

Is One Type of Fiber Better?

Both types of fiber are beneficial to health. Knowing the specific health benefit you are looking for will help point you in the direction of which type of fiber to add more of to your diet.

For Pooping 

Insoluble fiber helps bulk up your stools. It can speed up the passage of food in the digestive tract, preventing constipation and keeping bowel movements regular. Insoluble fiber may make diarrhea worse.

Soluble fiber's ability to help treat both diarrhea and constipation has been well studied. In particular, psyllium seems to be beneficial.

If you are experiencing loose bowels or diarrhea, soluble fiber can help by soaking up extra water in the digestive tract. This helps slow transit through the digestive tract, reducing urgency and bowel movement frequency.

In constipation, soluble fiber can soften hard stool, making it easier to pass. In a randomized, double-blind clinical study of 170 people with chronic constipation, psyllium proved better than docusate (a stool softener) for helping form softer stools and increase bowel movement frequency.

How Much Fiber Is Too Much?

According to the Dietary Guidelines for Americans 2020–2025, more than 90% of women and 97% of men do not meet recommended daily intakes for fiber. Verywell Health prefers to use inclusive terminology. But when citing health authorities or research, it will use the terms for sex or gender from those sources.

With most people struggling to get the recommended amount of fiber in their diet, getting too much usually isn't a concern. However, it is possible to have too much fiber in your diet.

Excessive fiber intake, especially through supplements, can cause an upset stomach and discomfort, including bloating, abdominal pain, gas, diarrhea, and intestinal blockage. High dietary fiber may also interfere with the absorption of some nutrients in the gastrointestinal (GI) tract.

If you start adding fiber to your diet, do so slowly. Adding too much fiber all at once may cause digestive upset, such as bloating and gas. Along with slowly increasing your fiber intake over a few weeks, be sure to get plenty of water each day to help prevent constipation.

Recommended Dietary Fiber Intake

The U.S. Department of Agriculture (USDA) recommends that healthy adults get a minimum of 14 grams of dietary fiber for every 1,000 calories. For adult females, this is at least 21–25 grams of fiber a day, and for adult males, this is at least 30–38 grams a day.

Children 1–8 years of age should get 19–25 grams of dietary fiber daily. Young females ages 9–18 should aim for about 26 grams of fiber per day, and young males ages 9–18 should get 31–38 grams per day.

Taking your time, chewing your food thoroughly, and keeping consistent with your fiber intake can help your body adjust and your stools become regular. 


Fiber is a form of carbohydrate found in plants. There are two main types of fiber. Soluble fiber dissolves in water and helps slow down digestion and as well as control cholesterol and blood sugar levels. Insoluble fiber does not dissolve in water and adds bulk to the stool, helping to keep bowel movements regular.

Both types of fiber provide health benefits, including decreasing the risk of certain chronic diseases such as some cancers, type 2 diabetes, and heart disease, supporting gut health, aiding in regular bowel movements, promoting satiety, and helping with weight management.

Soluble fiber may help treat both diarrhea and constipation, while insoluble fiber may help prevent constipation. Slowly increasing dietary fiber to the recommended amounts per day, along with drinking plenty of fluids, is recommended to help prevent an upset stomach.

Frequently Asked Questions

  • Can you take fiber supplements every day?

    Fiber supplements are generally regarded as safe for daily use. As always, consult a healthcare provider before changing your diet or adding a new supplement to your dietary routine.

  • What type of fiber is Metamucil?

    Psyllium fiber is the fiber found in Metamucil. It is a soluble fiber. Soluble fiber is a viscous, gel-forming fiber that doesn't ferment in the large bowel.

  • Is fiber better to eat in the morning or at night?

    It’s best to spread your fiber intake throughout your day. Try not to consume all your daily fiber at any one meal or snack, which may cause digestive upset. Nevertheless, when it comes to eating dietary fiber, anytime is better than not at all.

11 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Soliman GA. Dietary fiber, atherosclerosis, and cardiovascular disease. Nutrients. 2019;11(5):1155. doi:10.3390/nu11051155

  2. Werlang ME, Palmer WC, Lacy BE. Irritable bowel syndrome and dietary interventions. Gastroenterol Hepatol (N Y). 2019;15(1):16-26.

  3. McRorie JW Jr, McKeown NM. Understanding the physics of functional fibers in the gastrointestinal tract: an evidence-based approach to resolving enduring misconceptions about insoluble and soluble fiber. J Acad Nutr Diet. 2017;117(2):251-264. doi:10.1016/j.jand.2016.09.021 

  4. Barber TM, Kabisch S, Pfeiffer AFH, Weickert MO. The health benefits of dietary fibre. Nutrients. 2020;12(10):3209. Published 2020 Oct 21. doi:10.3390/nu12103209

  5. Wilson AS, Koller KR, Ramaboli MC, et al. Diet and the human gut microbiome: an international review. Dig Dis Sci. 2020;65(3):723-740. doi:10.1007/s10620-020-06112-w

  6. Kunzmann AT, Coleman HG, Huang WY, et al. Dietary fiber intake and risk of colorectal cancer and incident and recurrent adenoma in the prostate, lung, colorectal, and ovarian cancer screening trial. Am J Clin Nutr. 2015;102(4):881-890. doi:10.3945/ajcn.115.113282

  7. Partula V, Deschasaux M, Druesne-Pecollo N, et al. Associations between consumption of dietary fibers and the risk of cardiovascular diseases, cancers, type 2 diabetes, and mortality in the prospective NutriNet-Santé cohort. Am J Clin Nutr. 2020;112(1):195-207. doi:10.1093/ajcn/nqaa063

  8. U.S. Food and Drug Administration. Questions and answers on dietary fiber.

  9. McRorie JW Jr. Evidence-based approach to fiber supplements and clinically meaningful health benefits, part 2: what to look for and how to recommend an effective fiber therapy. Nutr Today. 2015;50(2):90-97. doi:10.1097/NT.0000000000000089

  10. U.S. Department of Agriculture. Dietary Guidelines for Americans 2020–2025.

  11. Quagliani D, Felt-Gunderson P. Closing America's fiber intake gap: communication strategies from a food and fiber summitAm J Lifestyle Med. 2016;11(1):80-85. doi:10.1177/1559827615588079

By Brittany Poulson, MDA, RDN, CD, CDCES
Brittany Poulson, MDA, RDN, CDCES, is a registered dietitian and certified diabetes care and education specialist.