Prebiotics for gut health: Understanding the role of dietary fibers

Keep your gut and digestive system healthy with prebiotics. These microorganisms can strengthen gut health by promoting good bacteria that ward off pathogens in the intestinal tract and aid with constipation.

Prebiotics as dietary fibers

Dietary fibers, also called roughage or bulk, are parts of plant foods that the body can’t digest or absorb. Unlike fats, proteins and carbohydrates, dietary fibers are indigestible by the body.

Moreover, dietary fibers just pass relatively intact in the stomach, small intestine and colon, then out of the body. It is possible to classify fibers into soluble and insoluble, based on whether they dissolve in water or not.

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Soluble fibers

This type of dietary fiber can dissolve in water to make a gel-like material. Soluble fibers are known to help decrease blood cholesterol and glucose levels. Plus, they are commonly found in beans, apples, citrus fruits, carrots, barley, oats, peas and psyllium.

Insoluble fibers

This type of dietary fiber promotes the movement of material by the digestive system and increases stool bulk. Consequently, insoluble fibers are useful for people who suffer from constipation or irregular stools.

Some great sources of insoluble fiber include beans, whole-wheat flour, wheat bran, nuts and vegetables, including cauliflower, green beans and potatoes.

Prebiotics for gut health: Understanding the role of dietary fibers
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Furthermore, the amount of soluble and insoluble dietary fibers is different in various plant foods. Hence, in order to reap great health benefits, you must eat a wide variety of high-fiber foods. 

Prebiotics are indigestible human enzymes that can be used as food for good colonizing microorganisms or are known as probiotics in the gut. Both prebiotics and probiotics help fuel gut microbes to promote and assist with digestion. 

As a result, prebiotics and probiotics in the gut may produce substrates that positively impact overall health, especially strengthening immunity and warding off disease. 

Not all fibers are prebiotics; in fact, it is the other way around. Prebiotics are a type of dietary fiber. Fructans and galactooligosaccharides (GOS) are only two examples of prebiotic fibers. 

For a dietary fiber to be considered a prebiotic, it can pass through the gastrointestinal tract undigested and must be able to stimulate the growth and/or activity of some good bacteria in the large intestine.  

Moreover, many health researchers have been gaining interest in the use of prebiotic fibers in fitness. Many people learned a broader understanding of how beneficial bacteria are in the gut, specifically as prebiotic fibers help support the digestive and immune systems. 

Numerous individuals are being aware of the number of factors affecting the decrease of good bacteria in the gut, like stress, antibiotics and poor diet. Therefore, the gut may experience bacterial imbalance [1]. 

Why does your gut need prebiotics?

Prebiotics are important to overall health. Although more research studies are needed to further understand all the ways prebiotics can help the body. Additionally, prebiotics can be naturally found in some high-fiber foods but are sometimes added to certain foods and dietary supplements.

There are numerous studies exploring prebiotics and gut health. For instance, two research studies found that prebiotics can regulate gut inflammation [2], manage constipation [3] and support overall digestive health, specifically those in supplemental and food forms. 

In a 2018 research trial, the researchers involved 44 individuals with gastrointestinal disorders that can cause flatulence. The health experts further investigated how prebiotic supplements can aid in reducing symptoms compared when following a low-FODMAP diet. Both methods were found to be equally effective after four weeks of the experiment [4].

Moreover, in another research study in 2018, health researchers concluded that prebiotics, by themselves or in combination with probiotics, could benefit patients with irritable bowel syndrome [5]. 

They derived the findings after reviewing several dozen studies focusing on the effectiveness of several components in managing irritable bowel syndrome, namely antibiotics, prebiotics, probiotics and synbiotics, which are a mixture of probiotics. 

After a few years, another review was made in 2020 involving 33 randomized control trials, and the researchers reached the same conclusions [6]. 

Additionally, a research study suggests that prebiotic supplementation can help with constipation as it encourages more regular, frequent and well-formed bowel movements [7]. Hence, when you are constipated, prebiotics can be used as a laxative [8]. 

Benefits of a prebiotic diet

Normalizes bowel movements

Dietary fibers may increase the weight and size of the stool and soften it, making it helpful for people with constipation as a bulky stool is easier to pass. When you have loose, watery stools, dietary fibers like prebiotics can help solidify the stool as it absorbs water and adds bulk to the stool.

Helps keep the bowels healthy

Following a high-fiber diet can decrease your risk of developing hemorrhoids and small pouches in the colon, called diverticular disease.

Many studies concluded that a high-fiber diet could also reduce the risk of colorectal cancer. Some dietary fibers are fermented in the colon; however, health scholars are still looking at how this may contribute to the role of preventing diseases of the colon.

Reduces cholesterol levels

Soluble fibers, like beans, oats, flaxseed and oat bran, can help reduce total blood cholesterol levels by decreasing low-density lipoprotein or bad cholesterol levels. Research shows that high-fiber foods may have other health benefits for the heart, like lowering blood pressure and inflammation.

Aids in controlling blood sugar levels

People with diabetes need soluble fibers that may slow down the absorption of sugar and manage blood sugar levels. Following a healthy diet with insoluble fibers may also lower the risk of the development of type 2 diabetes.

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Help achieve a healthy weight

Here’s for fitness people out there! Eating high-fiber foods with prebiotics can be more filling than low-fiber foods. Hence, you are most likely to eat less and stay satisfied for longer hours. Plus, high-fiber foods tend to be less energy dense, meaning that they contain fewer calories for a similar volume of food.

For longevity

Research suggests that eating more dietary fiber, particularly cereal fiber, is linked to a lowered risk of dying from cardiovascular disease and certain types of cancers.

7 foods rich in prebiotics

Prebiotics can be naturally acquired in many foods, particularly in vegetables, fruits and whole grains. Eating a varied diet allows you to consume plenty of prebiotics from foods without needing to take supplements. Some foods rich in prebiotics are the following: 

1. Apples

Some of the major vitamins and minerals of apples include vitamin C, antioxidants and, of course, dietary fiber. The fiber in apples contains pectin, which promotes the growth of good bacteria in the gut and lowers harmful bacteria. Also, the flesh of apples offers vast health benefits. It contains many critical nutrients that may benefit overall health. 

2. Bananas

Bananas offer various vitamins, minerals and prebiotic fiber, including small amounts of inulin. The fruit can aid in increasing healthy bacteria in the gut and reducing bloating. Bananas can be eaten either raw or cooked.

Prebiotics for gut health: Understanding the role of dietary fibers

3. Dandelion greens

Dandelion greens contain high prebiotic fiber with 3.5 grams per 100-gram serving, including inulin. 

In addition, dandelion greens have antioxidants, which help prevent damage to your cells that can cause fatal diseases, including cancer, cardiovascular disease and Alzheimer’s disease. You can simply add dandelion greens to green juices, salads and smoothies.

4. Garlic

Garlic refers to an herb that adds flavor and nutrients to all kinds of foods. It is a great source of inulin and FOS that boosts good gut bacteria and has been used for many centuries for overall health. 

While garlic has a wide range of health benefits when eaten raw, you can surely benefit from adding it to your cooking.

5. Chicory root

Chicory root has a coffee-like flavor and can be made as tea, which is a great alternative to coffee. This plant root is an excellent source of prebiotics, not to mention it is also high in antioxidants. 

6. Whole oats

Whole oats contain high fiber, specifically beta-glucan fiber, and resistant starch, which has been associated with beneficial gut bacteria. These can be cooked and are often found in prepackaged foods. Moreover, they are also known to help with blood sugar control and digestion.

7. Onions 

Onions contain prebiotics, antioxidants and flavonoids– all are beneficial compounds to prevent cancer and other chronic diseases. Also, onions have inulin and FOS that can strengthen gut health and help with the immune system. 


Dietary fibers, also called roughage or bulk, are parts of plant foods that the body can’t digest or absorb. One type of dietary fiber is a prebiotic fiber that is greatly beneficial in keeping the gut and digestive system healthy. 

Over the years, many health experts have been studying the different facets of the relationship between prebiotics and gut health. Some of the notable findings are prebiotics can regulate gut inflammation, manage constipation and help with irritable bowel syndrome and regular bowel movements. 

Generally, when you add prebiotics to your daily diet, you can normalize your bowel movements, reduce cholesterol levels, control blood sugar and achieve a healthy weight. Some of the foods you need to eat to increase prebiotic intake are apples, bananas, dandelion greens, garlic, Chicory root, whole oats and onions.

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