8 Proven Health Benefits of Dietary Fiber

Dietary fiber is essential for our digestive and bowel health. It regularizes bowel function and improves gut health. This is one of the benefits we get when we eat whole plant foods.

There are many studies that suggest that fiber intake reduces the risk of chronic diseases (1, 2).

Our gut plays a crucial role in preventing diseases. Most benefits of dietary fiber can be attributed to the activity in the gut due to the consumption of adequate fiber.

It has been reported that an average American only consumes only half the recommended daily intake of fiber in spite of its various benefits.

In such cases where one is not receiving enough fiber through food, there are fiber supplements available to increase the overall fiber intake.

What Is Fiber?


Let’s look at some basics about fiber. In simple words, dietary fiber is a carbohydrate that is resistant to digestion and doesn’t get absorbed in the small intestines (3). This means that the body cannot break down fiber. Fiber is sometimes also referred to as roughage. It usually passes through the body without undergoing much change.

Broadly, there are two types of fiber – soluble and insoluble fiber. This classification is based on their water solubility and the way they react to the digestion process. As the names suggest, soluble fiber dissolves in water and can be used by the gut upon metabolization.

It undergoes some sort of form change during the digestion process but is not absorbed by the body. It is converted to a gel-like mass and is excreted out. This kind of fiber is found in high concentrations in legumes like kidney beans, black beans, lentils, and peanuts. Oats, grains and some fruits and vegetables also contain healthy doses of soluble fiber. Brussel sprouts are another healthy source of soluble fiber.

Insoluble fiber, on the other hand, doesn’t dissolve in water and doesn’t go through any change through the digestive process. Insoluble fiber is found in many seeds and also in the skin of a few plant products like the outer shell of corn kernels, the skin of grapes and green peas. Wheat bran and whole grains also contain insoluble fiber.

Most plant foods contain a balance of both soluble and insoluble fiber which is greatly beneficial to the body. Another way to understand fiber is by categorizing it based on whether or not the healthy gut bacteria can use it. We can call this fermentable (can be used) and non-fermentable bacteria (cannot be used by the gut bacteria).

What Are Fiber Supplements?

Fiber Supplements

In America, less than 5% of people have been reported to have an adequate intake of dietary fiber. Fiber supplements can be used to increase the daily intake of fiber. Fiber supplements are concentrated forms of fiber that come in many forms like tablets, capsules, powder and even gummies (4).

Some fiber supplements are extracted from plants whereas others are made in a lab and are referred to as “functional fibers”.

Fiber supplements are generally a safe and recommended way to increase fiber intake. In case, you suffer from a pre-existing medical condition, it is best to discuss with your doctor about choosing the right kind of fiber supplement.

The 4 Types of Fiber Supplements

Inulin (Fiber Choice)

Inulin is a type of prebiotic fiber. Prebiotic fiber gets fermented when it enters the colon and this process results in an increase in the desirable bacteria in the colon (5, 6).

Inulin is very beneficial because these important bacteria colonies in the colon play a crucial role in how well the body absorbs nutrients and even helps in issues related to anxiety and appetite by producing related hormones. Inulin is usually available in a chewable tablet form.

Methylcellulose (Citrucel)

Another commonly available soluble fiber is methylcellulose. It is made from cellulose, which is an important structure in plants. Unlike psyllium, methylcellulose is non-fermentable, which means that it is not likely to result in bloating and gas.

Citrucel with SmartFiber is one of the most commonly found products of methylcellulose. It is usually available in the form of powder and caplets.

Methylcellulose has another role in the culinary world and is often sold as a thickener. It has a unique chemical structure which makes it dissolve only in a cold liquid and not in a hot one.

Psyllium (Metamucil)

Another type of fiber supplement is Psyllium which is also known as ispaghula. It is derived from the seeds of the Plantago ovata plant. It is a soluble fiber which means that it absorbs water in the stomach and makes bowel movement easier.

Since Psyllium soaks up water and increases in size very rapidly, it is important to have plenty of fluids while taking this supplement to avoid any intestinal obstruction. Psyllium also contains some insoluble fiber which makes it pass through the gut almost intact and also provides enough bulk for an efficient and regular bowel movement (7).

Psyllium also has prebiotic properties because it aids the growth of healthy colonies of bacteria in the gut.

Wheat Dextrin (Benefiber)

A byproduct of the plant called wheat dextrin is also used as a fiber supplement. It is a soluble fiber that is very easy to add to your diet and is extensively used in the food industry. Because it is tasteless and can dissolve into both cold and hot liquids, it is fairly easy to incorporate into your diet.

Wheat dextrin is also used in cooking and unlike methylcellulose, it doesn’t thicken. It is a soluble fiber which is helpful in managing blood sugar and preventing gastrointestinal disorders (8).

8 Benefits of Fiber Supplements

Improves Gut Health By Feeding “Good” Bacteria

To understand how fiber benefits us by keeping our gut health, we need to first understand a little bit about the gut microorganisms that live in us. There are trillions of microorganisms living in our intestinal tract. Of which a majority are bacteria.  They are collectively called the gut microbiota (9).

The gut microbiota is vital in the absorption of nutrients and minerals, the synthesis of enzymes, vitamins, and amino acids, and the making of short-chain fatty acids (10).

There is a symbiotic relationship between these gut bacteria living in our digestive system and us. We provide them a safe space to live and food for survival. In turn, they help us by performing certain functions that the human body cannot perform by itself.

Now, what role does fiber play in all of this? The gut microbes need food for survival like any living organism. But most of the nutrition we get from food – carbohydrates, protein, and fats get absorbed by the bloodstream even before they reach the large intestines where these microbes reside.

Here is where adding a fiber supplement to your diet can play a crucial role because the human body doesn’t have the required enzymes to digest and absorb fiber. It reaches the large intestine without breaking down. The good news is that the gut bacteria have the required enzymes to digest most of the fiber.

Some types of fiber supplements are prebiotic which means that they help promote the growth of some of these “good” bacteria, which in turn can have great benefits for our health (11).

These friendly bacteria produce certain short-chain fatty acids which may be helpful in reducing the risk of developing gastrointestinal disorders, cancer, and cardiovascular disease (12).

Summary: Fiber feeds the friendly gut bacteria which in turn promotes a healthy gut by fostering a balance of healthy microbes in the intestines. This promotes healthy digestion and helps prevent various diseases.

May Help Lose Weight

Fiber adds bulk to the diet and keeps you feeling full after eating. It reduces hunger post meals by sending early and prolonged signals of satiety. Fiber soaks up water while it is in the stomach and intestines and this slows down the process of digestion and absorption of nutrients (13).

A study conducted in 2001 in Boston indicates that when an additional 14 grams of fiber was given regularly to some participants, they experienced a 10% decrease in calories consumed and also recorded weight loss. This was even more distinct in obese participants (14).

Another study conducted amongst obese women concluded that supplementing with fiber resulted in reducing hunger and that fiber can be used in the treatment of obesity along with a low-calorie diet (15).

It is also important to note that not all types of fiber have the same effect when it comes to weight loss. Some types of fiber don’t seem to have any effect on weight whereas some types of soluble fiber have shown notable improvement.

Summary: Some types of fiber can help in losing weight by adding bulk, increasing satiety and reducing calorie intake.

Helps Improve Short-Term Glycemic Control (Postprandial)

Refined carbohydrate foods are usually stripped off most of their fiber content and hence have a higher glycemic index. High fiber foods usually have a lower glycemic index. It has been noted that high viscosity fibers in particular exhibit a significant effect in improving glycemic control. 

Viscous fiber is one that thickens and becomes gel-like when it interacts with any fluid (16). The body absorbs broken down nutrients that are passed through a thin liquid to the small intestines.

So when we add a viscous fiber to the diet, it thickens the contents that are passing through the intestines and slows down the interaction between digestive enzymes with nutrients and slows down the absorption of glucose and other nutrients (17).

A 2008 study conducted in Bloomington (IN) amongst 50 overweight men and women showed that consumption of Methylcellulose with their breakfast reduced their postprandial blood sugar readings (18).

Summary: The low glycemic index of viscous, soluble fibers helps prevent spikes in blood sugar by slowing down the absorption of glucose in the small intestines.

Helps Improve Long-term Glycemic Control In Metabolic Syndrome & Type 2 Diabetes

It is easier to study postprandial glucose levels to assess glycemic control of fiber and it is useful to an extent. Studying the glycemic control of fiber in patients at risk of or suffering from type 2 diabetes requires longer studies.

There have been several studies conducted to determine the effect of gel-forming fiber on such people and have recorded that there has been significant improvement in fasting glucose levels, insulin, and HbA1c.

A 6-month long study performed amongst subjects with metabolic syndrome showed that a controlled diet was not as effective in improving glycemic control. But when psyllium was added twice a day along with a controlled diet, a significant improvement was seen in fasting glucose, insulin and HbA1c (19).

Summary: Gel-forming fibers like psyllium have shown significant improvement in glycemic control in people with metabolic syndrome and type 2 diabetes.

Improves Cardiovascular Health By Lowering Cholesterol

Some studies have shown an impressive reduction in cholesterol values in individuals by increasing their fiber intake (20, 21).

This benefit is mainly from the viscous soluble fibers which are primarily gel-forming fibers and they reduce cholesterol levels by trapping and eliminating bile.

However, there are some other studies that go to show that these changes in cholesterol are not substantial enough (22). Fiber supplementation in isolation may not be adequate to reduce cholesterol levels. Adding a viscous, soluble along with other diet changes and lifestyle changes are required for an effective treatment against high cholesterol.

Although there needs to be a lot more research to establish long term benefits of fiber intake on cholesterol, there have been a few observational studies that concur that adequate fiber intake reduces the risk of coronary heart disease (23).

Summary: Some types of viscous, soluble fibers are known to reduce cholesterol levels. There also seems to be an inverse relationship between the consumption of adequate dietary fiber and the risk of coronary heart disease.

Reduces Constipation & Improves Stool Form

Chronic constipation is a very common problem and there are almost 8 million cases of constipation in the United States every year (24).

One of the foremost benefits of increased fiber intake is a regular bowel movement and reduced constipation (25). In a study conducted in London, 77% of people suffering from constipation responded to increased fiber intake (26).

In general, there are some fibers that increase the water content of the stool and are known to have a laxative effect. Soluble fibers that form a gel in the digestive tract and are not readily fermentable are helpful to ease constipation (27).

Psyllium is a good example of this kind of fiber. It traps water in the intestines and increases the water content of the stool which eases the defecation process (28). This also helps in normalizing stool form.

There are some fibers like wheat dextrin which may cause constipation because they add to the dry mass of the stool. Insufficient fluid intake along with fiber supplements may be another cause (29), (30).

It is recommended to consult a doctor before choosing the type of fiber supplement to treat chronic constipation.

Summary: Increasing fiber intake is known to have a positive effect when treating constipation. It is important to choose the right kind of fiber to get the best results.

May Reduce Risk of Colorectal Cancer

There are almost 1.8 million deaths caused by colorectal cancer making it the third leading cause of cancer deaths worldwide (31).

It is difficult to singularly attribute cancer prevention to fiber, but many scientists believe that a high fiber diet plays a significant role in reducing its risk (32, 33).

There is no study to prove a direct link between fiber and cancer prevention. A high fiber diet usually involves eating a lot of whole foods including fresh vegetables and fruits all of which also contribute to overall good health and play a role in cancer prevention.

Summary: There is some evidence to suggest that a high fiber diet may reduce the risk of colorectal cancer. There is not enough evidence to prove the direct benefits of fiber in preventing cancer.

May Help Improve Irritable Bowel Syndrome

Irritable bowel syndrome or IBS is a common chronic gastrointestinal disorder that causes pain in the stomach, flatulence, diarrhea, and constipation. It is popularly believed that IBS is caused by a reduced intake of fiber.

Most doctors recommend increasing fiber intake to relieve IBS symptoms (34). However, different forms of fiber react differently and have different effects on these symptoms (35).

In particular, soluble fibers that do not easily get fermented (like psyllium) are most beneficial to people with IBS. It is important to start fiber supplements gradually so as to ease into a regular intake to avoid discomforts like bloating during the transition period.

Summary: Some soluble fiber supplements like psyllium that are moderately fermentable can be used to treat IBS.

Who Should Buy Fiber Supplements?

Since most Americans do not get sufficient fiber from legumes, fruits, and vegetables, most people can benefit from it. However, there are certain groups of people who might be benefitted more than others.

People with gastrointestinal disorders like constipation, irregular bowel movements, and IBS can benefit by adding soluble fiber to their diet.

Diabetes is a range of metabolic diseases where people suffer due to a lack of insulin or because of insulin resistance. Because fiber helps with both short-term and long-term glycemic control, adding a fiber supplement will be beneficial for people with type 2 disease.

People who travel a lot end up having to eat out a lot and might have trouble getting enough fiber through processed foods. This is another group of people who will be benefited from fiber supplements.

Lastly, people trying to lose weight or struggle with weight gain can benefit from fiber supplements because fiber increases a feeling of fullness and reduces appetite.

What to Look for in Fiber Supplements?

Choosing the right fiber supplement will need to be based on the reason you are looking to supplement fiber. Soluble fiber like psyllium will be the right choice if you are looking to relieve constipation, lower cholesterol, treat diarrhea, regulate bowel movement and even treat IBS.

It is also important to think about the cost when choosing a fiber supplement. Fiber should not be expensive because it can easily be sourced from natural sources. Some types of fiber supplements are derived in a lab and may cause further digestive problems.

The labels should be clear and transparent, meaning they should give you a clear indication of how much fiber you are going to get and what type of fiber it is. This is especially important if you are looking to buy a fiber blend.

In cases of severe gastrointestinal disorders, it is best to consult a physician to identify the right kind of fiber supplement keeping in mind all the above factors.

The Side Effects of Fiber Supplements

Even though fiber supplements are derived from natural sources, they can cause bloating in some people, especially at the beginning stages of supplementing. This can be overcome by starting gradually with small doses and go up from there instead of starting with a big dose (36).

In the beginning, it might be helpful to start with a non-fermentable fiber to ease into a high fiber diet instead of shocking your system. It might also help to add a probiotic supplement to restore the balance in your gut microbiome.

It is extremely important to increase your fluid intake when increasing fiber intake. Especially because soluble fibers act like a sponge absorbing water. They can cause constipation when there is insufficient fluid intake.

The Final Note

Fiber is extremely helpful in keeping the digestive system healthy. It also plays a significant role in preventing chronic illnesses and ensuring good health in the long run.

Fiber feeds the good bacteria in the gut and fermentable fiber keeps the colon wall healthy. Certain types of high viscosity fibers help in reducing appetite, lowering cholesterol and blood glucose levels.

Fiber is also helpful to treat various bowel related disorders like diarrhea, constipation and it also regulates bowel movements and improves stool form.

It is best to get a variety of fiber from natural sources through fruits, vegetables, seeds, grains, and legumes to maintain a healthy lifestyle. There are several natural fiber supplements available in case you are not able to get enough fiber through your diet due to various reasons.

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