Fiber Supplement Uses, Benefits, Dosages, Food Sources & Side Effects

Getting adequate amounts of fiber in the diet is important for developing and maintaining good gastrointestinal health and supporting metabolic health.

Without adequate amounts of fiber, the digestive tract cannot function properly, which can lead to many health disorders. This substance is also important for supporting the health of the gut microbiome and probiotic bacteria.

Fiber is also commonly referred to as “roughage” or “bulk”. A high-fiber diet is one that incorporates more foods including vegetables, fruits, and whole grains.

A nutritious high fiber content diet is correlated with a reduced risk of developing certain health conditions including cardiovascular disease and diabetes mellitus.

It is estimated that many people who live in North America and Europe are only getting about half of the fiber they need daily. Diets with high amounts of processed foods or poor vegetable and fruit content may be deficient.

This article will discuss what fiber is, how it works in the body, health benefits of fiber rich diets, food and supplement sources, recommended intake, as well as safety and side effects.

Fiber

Nutritional Supplement

Gut Health

Heart Health

Weight Loss

How It Works:

• Supports gastrointestinal and colon health
• Reduces hunger cravings between meals
• Promotes normal cholesterol levels and heart health

Dosage:

Between 4 - 24 g per day

Safety:

Rated Likely Safe

Top Fiber Products* ❯

View User Ratings* ❯

Fiber Overview

According to the Harvard T.H. Chan School of Public Health, fiber is a form of carbohydrate that the body cannot digest. [3]

Most carbohydrates can be broken down in the digestive tract into simple sugars or glucose molecules and used as energy.

However, non-digestible carbohydrates cannot be broken down into sugar molecules and pass through the digestive tract unmetabolized.

Dietary fiber are comprised of various substances including non-starch polysaccharides, resistant dextrins, oligosaccharides, resistant starch, beta-glucans, cellulose, pectins, chitins, lignins and inulin. [2]

The Mayo Clinic states that ensuring proper fiber and water intake helps the foods we eat to move quickly and easily through our digestive tracts. [1]

By decreasing the time that foods spend breaking down inside the intestines, the risk factors for certain health conditions may be decreased.

The Natural Medicines Comprehensive Database (NMCD) reports that some people use a high-fiber diet for bowel irregularities, constipation, diverticulosis (formation of bulging pockets in the lining of the colon), and irritable bowel syndrome (IBS).

Increasing your intake of this substance is also sometimes recommended to reduce risk factors for colorectal cancer, diabetes, heart disease, hemorrhoids, and hypercholesterolemia (high serum cholesterol). [2]

NMCD states that dietary fibers work by influencing how other nutrients and chemicals are absorbed from the gastrointestinal tract. By changing the make-up of the contents found in the gut, consumption of fibre-rich foods may support overall health and well-being [2]

Scientific studies support the hypothesis that fiber in the diet helps to increase satiety, decrease hunger, and provide a feeling of fullness.

Fiber increases the bulk of food and helps retain water, which may lead to feelings of satiety. This could support weight loss by promoting an appetite-supression effect.

Fiber also regulates the way the body uses sugars in food like glucose, lactose, maltose, and sucrose. It can slow down the rate at which these sugars are absorbed into the bloodstream, preventing spikes in blood glucose and insulin levels.

This effect can be helpful for helping to manage the long-term symptoms of type 2 diabetes mellitus. Many doctors recommend a high fiber diet to their patients with type 2 diabetes to help manage their condition through diet.

Types of Fibre

There are two forms of dietary fiber: soluble and insoluble.

Soluble fibers are found in oat bran, nuts, seeds, barley, beans, lentils and certain fruits and vegetables. These substances:

• Can be dissolved in water
• Can be fermented by colonic bacteria
• Can bind with fatty acids to form a gel-like substance in the intestines
• Enhances nutrient absorption from foods eaten
• Helps modulate blood-sugar levels
• Helps to lower serum cholesterol
• May extend feelings of fullness
• Prolongs stomach emptying

Soluble fiber may or may not be fermented by bacteria in the large intestine. If this does occur, then gas or bloating may result.

Insoluble fibre is going in wheat bran, whole grains and certain vegetables. These fibres do not form solutions with water in the gut. They:

• Add bulk and moisture to fecal mass in the intestines
• Cannot be dissolved in water
• Ease defecation
• Help keep intestinal pH in balance
• Help prevent constipation
• Are metabolically inert
• Promote regular bowel movements

Insoluble fiber is not generally fermented by colonic bacteria. However, resistant starch fiber can be fermented in order to produce short-chain fatty acids (SCFAs) when they are needed. [4]

Lignin is a major type of insoluble fiber and is thought to affect how quickly soluble dietary fiber is metabolized.

Soluble fibers can form a mucilage-like (mucous-like gel) substance inside the intestines. This slimy substance helps to decrease levels of fatty acids like cholesterol and regulate blood-glucose levels by slowing gastric emptying.

Insoluble fiber is believed to help improve gastrointestinal disorders like diverticulosis, hemorrhoids, and IBS by flushing out toxins in the GI tract as it passes through undigested.

This insoluble material may also help to remove carcinogenic (cancer-causing) substances from the digestive tract. They may also function as prebiotics, forming substrates that promote the growth of probiotic bacteria colonies.

Both soluble and insoluble fibers are important for supporting cardiovascular health. Studies have shown that increasing dietary intake of high-fiber foods can reduce blood pressure and inflammation. Soluble fiber has been shown to reduce cholesterol levels.

Fiber Health Benefits

A high-fiber diet may help you to:

• Have more regular bowel movements
• Manage blood-glucose levels
• Reduce fatty acids in the blood like triglycerides and cholesterol
• Strengthen the walls of the colon [5]

A low-fiber diet may have opposite effects and lead to constipation, imbalances in blood sugar and blood lipid levels as well as put strain on the intestinal wall.

It is thought that more fiber in the diet may also improve insulin sensitivity, reduce the risks of certain cancers, and support weight loss. However, more research is needed to demonstrate therapeutic efficacy for these claims.

In various studies, increasing dietary fiber intake has been seen to improve symptoms in people with digestive disorders including irritable bowel syndrome.

Fiber has prebiotic effects in the GI tract that increase the ratio between beneficial and harmful bacteria. Getting more of this substance in your diet can promote the growth of health-enhancing bacteria species like Lactobacillus and Bifidobacterium.

Specific types of fibres found in food sources have also demonstrated positive effects on health.

The NCMD has rated soluble beta-glucans as Likely Effective for lowering low-density lipoprotein cholesterol (LDL-C). [2]

Additionally, oligosaccharides are short-chain fatty acids that have been seen to have a protective effect on the lining of the large intestine.

Fiber and Heart Disease

Two large-scale Harvard research studies followed tens of thousands of people over many years and found that a high-fiber diet can lower the risk of heart disease in both men and women.

In one of those studies, high total dietary fiber (insoluble plus soluble) was found to lower coronary heart disease risk by 40%. A similar study involving only female nurses yielded similar results.

Eating a fiber-rich diet of plant-based foods is also linked to a reduced risk of developing metabolic syndrome, which is a set of factors that can increase the risk of developing heart disease.

Metabolic syndrome is marked by:

• Excess body weight
• Hyperinsulinemia (high insulin levels)
• Hypertension (high blood pressure)
• Hypertriglyceridemia (high serum triglycerides)
• Low levels of HDL-C (high-density lipoprotein cholesterol)

Various studies suggest that a high-fiber diet can help to protect against metabolic syndrome, which may subsequently reduce the risk of heart disease.

Blood Sugar and Type 2 Diabetes

Many people in the world are only consuming about half of the dietary fiber they need daily. Diets low in fiber and high in processed carbohydrates increase the risk of developing type 2 diabetes.

This type of diet can increase the risk of insulin resistance by more than 200% relative to a diet based on foods with a low glycemic index and high fiber intake. [3]

In research studies, eating soluble dietary fiber has been seen to reduce the postprandial (after eating) glucose response, which helps to keep insulin levels stable.

This effect can be beneficial for helping regulate blood-glucose levels in diabetics and pre-diabetics. It may also contribute to better weight management and overall health outcomes.

Digestive Health and Constipation

Constipation is a very common issue that often affects people who do not have adequate fiber levels in their diet.

Diets that commonly consist of high amounts of muscle meat foods, simple carbohydrates (sugars), hydrogenated fats, and other low-fiber foods can lead to constipation.

Further, many people fail to maintain adequate hydration. Low fiber and dehydration both contribute to hard feces and difficulty with bowel movements.

Being constipated keeps the foods we consume inside of our GI tracts longer. That can contribute to excess putrefaction (rotting) of foods in the intestines, which can negatively affect the bacterial balance of the GI tract.

Bacterial imbalance in the digestive system is thought to be a key cause of various gastrointestinal complaints.

Without adequate intake of fiber rich plant-based foods, it is more difficult for other types of food to move through the digestive tract and make their way out of the body.

Adequate dietary fiber may not only help to prevent and treat constipation but has also shown benefits for other common GI complaints including diverticulosis, IBS, and ulcerative colitis.

Fibre also helps to hold more water in the gastrointestinal tract, which may relieve constipation and promote regular bowel movements.

Anti-Cancer Research

Adequate dietary fiber intake is linked to a reduced risk for certain types of cancer based on epidemiological data.

The Harvard T.H. Chan School of Public Health reported results from a large-scale study completed in 2016 that linked a high fiber diet to reduced breast cancer risk. [3]

Researchers found that women who begin to eat a high-fiber diet in adolescence and early adulthood and continue eating this diet throughout their adult life are much less likely to develop breast cancer than women who do eat enough dietary fiber when young.

Other recent research has found that women who consume 38-77 grams of dietary fiber daily have a reduced risk for ovarian cancer relative to women who eat less fiber.

Studies to date have mostly failed to show any positive effects of dietary fiber on risk for developing colon cancer.

In one Harvard study of more than eighty-thousand women over sixteen years, eating foods high in fiber did not seem to affect either colon cancer rates or occurrences of colonic polyps which are often precursors to colon cancer.

More research is needed to understand the specific ways that dietary fiber affects the risks of developing certain diseases. Data available so far comes from population studies which establish correlation but not causation.

High-Fiber Foods

Animal muscle meats, dairy products, and eggs are not sources of fiber. It comes from exclusively from plant sources.

The Natural Medicines Comprehensive Database states that some of the best sources for soluble fiber are:

• Apples and pears
• Berries
• Citrus fruits
• Legumes and beans
• Oats and barley
• Potatoes
• Psyllium

Some of the best sources of insoluble fiber are:

• Cabbage
• Nuts
• Root vegetables
• Wheat bran and corn bran

Some other fiber-rich foods are avocado, Brussels sprouts, coconut, fig, artichoke, squash, flax seed, chia seed, and quinoa.

Fiber Supplements

Most health experts agree that whenever possible it is better to get fiber from fresh whole food sources rather than dietary supplements. These foods are nutritious and have additional health benefits when added to the diet.

For some people with certain health conditions or living situations this is not always possible though, and the use of fiber supplements may help increase fiber intake when dietary intake is lacking.

It is important to choose a high quality fiber supplement that clearly labels how many grams of this substance are provided in a standard dosage. Some supplements available may low amounts per serving, which would require you to take many dosages per day to meet your needs.

Some supplements may contain lower quality ingredients including a synthetic derivative of cellulose called methylcellulose, wheat dextrin, inulin, oligosaccharides, or calcium polycarbophil.

These sources of fiber can ferment in the gut, or do not gel, or may gel but then lose their “stickiness” as they move through the digestive tract. All of these factors make them less effective for aiding digestion and providing other health benefits. [5]

Psyllium fiber is a supplemental source that gels and stays gel-like throughout the digestive tract, helping it to work better in the body.

If you choose to take a supplement, then it is important to choose a high-quality fiber source that ideally is also organically-sourced and has not been genetically modified.

Increase your intake of dietary fiber slowly to help avoid gastrointestinal side effects like cramping, bloating, flatulence, and abdominal pain. These effects are all common if intake is increased too quickly.

Always ensure proper water intake along with supplementation. Most fiber supplements come in the form of a powder that can be mixed with a liquid like water or sugar-free juice.

If taken without enough liquid, some fiber supplements like psyllium and other bulking substances can expand and cause throat or intestinal blockages.

Fiber Dosages Per Day

The Natural Medicines Comprehensive Database states that the average American only gets between 12-17 grams of dietary fiber daily.

However, Mayo Clinic recommends that women should get between 21-25 grams daily while men should get between 30-38 grams of fiber per day. [1]

When taking a fiber supplement, it is still recommended to try and get the majority of your intake from the diet. Supplements are intended to increase dietary intake and not to replace it entirely.

Some research conducted on supplements suggests a maximum of 10 grams supplemental fiber a day. [6]

Fiber Safety and Side Effects

The NMCD states that there is insufficient evidence available to rate the safety of eating a high-fiber diet long-term. However, they also state that there is no reason to expect any safety issues.

People who routinely eat a low-fiber diet may experience gas, bloating, and possibly diarrhea if they increase their fiber intake too quickly. When people do experience adverse effects, they normally subside quickly without requiring intervention.

As mentioned earlier it is important to increase your fiber intake gradually, whether it is from dietary sources or supplements. Many experts recommend increasing intake by about 2-4 g per week and drinking at least 8 cups of water daily to help avoid digestive issues.

Fiber Interactions

The University of Maryland Medical Center reports that fiber supplements can affect the absorption of various types of medications including:

• Antidepressant drugs like Celexa, Lexapro, Paxil, and Prozac
• Antidiabetes drugs like insulin, metformin, and glimepiride
• Antiseizure drugs like Tegretol, Lamictal, and Frisium
• Cholesterol-lowering drugs like Lipitor, Crestor, and Zocor

It is best to seek medical advice beforehand about increasing your dietary fiber intake or beginning to take a supplement especially if you use any type of prescription drugs.

Speak with your doctor about the effects and benefits of increasing your fiber intake. They will be able to advise you on proper dosages to avoid side effects and the best way to increase your intake.

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