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All About Fiber

What’s the key to a healthier gut or why is it admired? Check out this article that tells all there is worth to know about fiber!

Dietary fiber, also identified as roughage or bulk, encompasses the components of plant-based foods that our body cannot metabolize or assimilate. In contrast to other dietary elements such as fats, proteins, or carbohydrates, which the body disassembles and absorbs, fiber avoids digestion by the body. Instead, it traverses the digestive system, moving relatively intact through the stomach, small intestine, and colon, before exiting the body. It contributes to the regulation of sugar utilization, aiding in the management of appetite and blood sugar levels.

The two varieties of fiber

  1. Soluble fiber
    This variety of fiber dissolves upon contact with water, resulting in the creation of a gel-like substance. It possesses the ability to reduce blood cholesterol and glucose levels. Foods rich in soluble fiber include oats, peas, beans, apples, citrus fruits, carrots, barley, and psyllium.
  2. Insoluble fiber
    Insoluble fiber facilitates the movement of material through the digestive system and contributes to an increase in stool bulk. As a result, it can be particularly beneficial for individuals who experience constipation or irregular bowel movements. Foods like whole-wheat flour, wheat bran, nuts, beans, and vegetables such as cauliflower, green beans, and potatoes are notable sources of insoluble fiber.

The relative quantities of soluble and insoluble fiber vary across different plant-based foods. To achieve maximum health benefits, it is advisable to diversify our consumption of high-fiber foods.

Benefits of a High-Fiber Diet

  1. Normalizes bowel movements
    Dietary fiber enhances both the weight and size of stool while softening it. A bulkier stool is easier to pass, reducing the likelihood of constipation. In cases of loose, watery stools, fiber may contribute to solidifying the stool by absorbing water and augmenting its bulk.
  2. Supports gastrointestinal health
    A high-fiber diet can decrease the risk of developing conditions like hemorrhoids and diverticular disease, characterized by small pouches forming in the colon. Studies also suggest that a high-fiber diet may potentially reduce the risk of colorectal cancer. A portion of the fiber undergoes fermentation in the colon, and researchers are investigating its potential role in preventing colon-related diseases.
  3. Lowers cholesterol levels
    Soluble fiber, present in foods such as beans, oats, flaxseed, and oat bran, can help reduce total blood cholesterol levels, including low-density lipoprotein, commonly referred to as “bad” cholesterol. Additionally, research indicates that high-fiber foods may offer other cardiovascular benefits, such as reducing blood pressure and inflammation.
  4. Regulates blood sugar levels
    Particularly in individuals with diabetes, fiber, specifically soluble fiber, can slow down sugar absorption, aiding in the improvement of blood sugar levels. A healthy diet encompassing insoluble fiber may also diminish the risk of developing type 2 diabetes.
  5. Supports weight management
    High-fiber foods tend to be more satiating than low-fiber counterparts, often leading to reduced food consumption and prolonged satisfaction. Moreover, high-fiber foods typically require more time to consume and possess lower energy density, translating to fewer calories per unit of food volume.
  6. Enhances longevity
    Research indicates that elevating dietary fiber intake, especially from cereal sources, is linked to a decreased risk of mortality associated with cardiovascular disease and various types of cancer.

How Much Fiber Is Required?

  • For individuals aged 50 or younger
    Men: 38 grams
    Women: 25 grams
  • For individuals aged 51 or older
    Men: 30 grams
    Women: 21 grams

Food High in Fiber

  • Whole-grain products
  • Fruits
  • Vegetables
  • Beans, peas, and other legumes
  • Nuts and seeds

On the other hand, refined or processed foods, such as canned fruits and vegetables, pulp-free juices, white breads and pastas, and non-whole-grain cereals, exhibit lower fiber content. During the grain-refining process, the outer layer (bran) of the grain is removed, resulting in reduced fiber levels. Although enriched foods have some B vitamins and iron reintroduced after processing, fiber is not restored.

Fiber Supplements and Fortified Foods

Generally, whole foods tend to be superior to fiber supplements. Fiber supplements like Metamucil, Citrucel, and FiberCon do not offer the same variety of fibers, vitamins, minerals, and other advantageous nutrients that foods provide.

Another approach to increase our fiber intake is by consuming food items like cereal, granola bars, yogurt, and ice cream with added fiber. This additional fiber is commonly labeled as “inulin” or “chicory root.” Some people may experience flatulence after consuming foods enriched with extra fiber.

Nonetheless, certain people might still require a fiber supplement if dietary adjustments prove insufficient or if they are managing specific medical conditions such as constipation, diarrhea, or irritable bowel syndrome. It is advisable to consult a healthcare professional before considering fiber supplements.

How to Add More Fiber

  1. Opt for a high-fiber breakfast cereal
    Favor cereals bearing labels with “whole grain,” “bran,” or “fiber” that features 5 or more grams of fiber per serving. Alternatively, introduce a few tablespoons of unprocessed wheat bran into our preferred cereal.
  2. Transition to whole grains.
    Strive to include at least half of grain consumption as whole grains. Look for bread varieties that list whole wheat, whole-wheat flour, or another whole grain as the primary ingredient on the label, with a minimum of 2 grams of dietary fiber per serving. Explore the use of brown rice, wild rice, barley, whole-wheat pasta, and bulgur wheat.
  3. Enhance the fiber content in baked goods.
    When baking, contemplate substituting half or the entirety of white flour with whole-grain flour. Experiment with incorporating crushed bran cereal, unprocessed wheat bran, or uncooked oatmeal into muffins, cakes, and cookies.
  4. Use legumes.
    Beans, peas, and lentils are outstanding sources of fiber. Incorporate kidney beans into canned soup or a green salad. Alternatively, prepare nachos using refried black beans, an abundance of fresh vegetables, whole-wheat tortilla chips, and salsa.
  5. Increase the consumption of fruits and vegetables.
    Fruits and vegetables not only supply ample fiber but also offer a wealth of vitamins and minerals. Aim to consume five servings or more each day.
  6. Make the snacks meaningful.
    Opt for fresh fruits, raw vegetables, low-fat popcorn, and whole-grain crackers as snack options. Additionally, a handful of nuts or dried fruits can serve as a nutritious, high-fiber snack—although it’s essential to be mindful of their calorie content.

High-fiber foods are beneficial for health. However, excessive fiber intake at a rapid pace may encourage the occurrence of intestinal gas, abdominal bloating, and cramping. Gradually increasing fiber intake in the diet over several weeks permits the adaptation of the natural bacteria in the digestive system to this alteration.

Moreover, a sufficient amount of water should be consumed. Optimal fiber functionality is achieved when water is absorbed, resulting in softer and more voluminous stool.

Naturally occurring plant fibers

  • Cellulose and hemicellulose
    These are insoluble fibers found in cereal grains and the cell walls of many fruits and vegetables. They have the capacity to absorb water and contribute to stool volume, potentially resulting in a laxative effect.
  • Lignins
    This insoluble fiber is discovered in wheat and corn bran, nuts, flaxseeds, vegetables, and unripe bananas. It stimulates mucus secretion in the colon and increases stool bulk, with a potential laxative effect.
  • Beta-glucans
    This soluble, highly fermentable fiber is present in oats and barley. It undergoes metabolism and fermentation in the small intestine and acts as a prebiotic. Although it can enhance stool volume, it doesn’t possess a laxative effect and may aid in regulating blood glucose and cholesterol levels.
  • Guar gum
    Derived from seeds, this soluble, fermentable fiber exhibits a viscous gel-like texture and is frequently used as a thickening agent in foods. It is metabolized and fermented in the small intestine, without inducing a laxative effect. It may assist in normalizing blood sugar and cholesterol levels.
  • Inulin, oligofructose, oligosaccharides, and fructooligosaccharides
    These soluble, fermentable fibers are found in onions, chicory root, asparagus, and Jerusalem artichokes. They can potentially increase stool bulk with a laxative effect, aid in blood glucose regulation, and act as a prebiotic. Individuals with irritable bowel syndrome may exhibit sensitivity to these fibers, which could lead to bloating or stomach discomfort.
  • Pectins
    This highly fermentable, soluble fiber is present in apples, berries, and other fruits. While it has limited impact on stool volume and laxative effects, its gelling properties may slow down digestion and support the normalization of blood sugar and cholesterol levels.
  • Resistant starch
    This soluble, fermentable fiber is found in legumes, unripe bananas, cooked and cooled pasta, and potatoes. It acts as a prebiotic, increasing stool bulk with minimal laxative effect. It may contribute to regulating blood sugar and cholesterol levels.

Manufactured functional fibers, some of which are extracted and modified from natural plants

  • Psyllium
    This soluble, viscous, nonfermentable fiber is derived from psyllium seeds. It has the capacity to retain water, softening and increasing stool bulk, potentially resulting in a laxative effect. Psyllium is a component of over-the-counter laxatives and high-fiber cereals and may aid in normalizing blood sugar and cholesterol levels.
  • Polydextrose and polyols
    These soluble fibers are composed of glucose and sorbitol, a sugar alcohol. They can enhance stool bulk and have a mild laxative effect, with minimal influence on blood sugar or cholesterol levels. They serve as food additives used for sweetening, texture improvement, moisture retention, or increasing fiber content.
  • Inulin, oligosaccharides, pectins, resistant starch, and gums
    These soluble fibers are derived from the plant foods listed above but are isolated or modified into a concentrated form added to foods or fiber supplements.

Fiber and Health

  • Heart disease
  • Diabetes
  • Diverticular disease
  • Constipation

Heart disease

In the context of heart disease, water is drawn into the gut by soluble fiber, forming a gel that can decelerate the process of digestion. This, in turn, might assist in the prevention of surges in blood glucose levels following meals and in the reduction of hunger. The management of blood glucose and body weight is crucial due to their roles as risk factors for diabetes, a condition that doubles the likelihood of heart disease development.

Furthermore, blood cholesterol levels could be lowered by soluble fiber through its interference with bile acid production. The liver utilizes cholesterol in the synthesis of bile acids. Soluble fiber binds to bile acids in the gastrointestinal tract and facilitates their removal from the body. Consequently, with a diminished pool of available bile acids, the liver extracts cholesterol from the bloodstream to generate new bile acids, ultimately resulting in reduced blood cholesterol levels. A meta-analysis of 67 controlled trials revealed a moderate advantage of dietary soluble fiber in reducing both total and LDL cholesterol levels.

Epidemiological investigations have associated a heightened consumption of dietary fiber with a decreased risk of heart disease and fatalities linked to cardiovascular conditions. In extensive cohorts of health professionals, both male and female, it was observed that greater intake of cereal fibers corresponded to a diminished risk of heart disease and heart attacks. It’s worth noting that in these studies, the term “cereals” alluded to the minimally processed whole grains containing the germ, bran, and endosperm. Examples include steel-cut oats, quinoa, brown rice, millet, barley, and buckwheat.

Additionally, an elevated fiber intake has been associated with a reduced risk of metabolic syndrome. This syndrome is characterized by a cluster of factors that heighten the chances of developing heart disease and diabetes, including high blood pressure, elevated insulin levels, excess weight (especially around the abdomen), heightened triglyceride levels, and diminished levels of HDL (good) cholesterol.


Constipation is generally characterized by experiencing three or fewer weekly bowel movements, encountering difficulty or discomfort during bowel movements, or passing small, hard “pebbly” stool. Occasional episodes of constipation are commonplace, but persistent constipation that remains unresolved can adversely impact one’s quality of life and manifest as symptoms like bloating, cramping, and, on occasion, nausea. Chronic constipation elevates the risk of developing diverticular disease and hemorrhoids.

Lifestyle behaviors that aid in alleviating constipation encompass the consumption of more fiber derived from fruits, vegetables, and whole grains, increased water intake, and regular physical activity. Several factors contribute to the beneficial effects of fiber on constipation. Certain types of soluble fiber have the capacity to bind with water, resulting in the formation of a gel that facilitates stool softening and increased bulk. In contrast, insoluble fibers provide mild irritation to the lining of the intestines, promoting the secretion of water and mucus to stimulate stool movement. Additionally, specific fibers serve as prebiotics, serving as nourishment for gut bacteria, which ferment fibers into short-chain fatty acids and enhance water content in the intestines, culminating in the production of more pliable and easily passed stools.

Considering the diverse actions of different fiber types in relation to constipation, it is advisable to include a variety of high-fiber foods sourced from whole grains, fruits, legumes, and vegetables in one’s diet. Gradually augmenting fiber intake is recommended, as a sudden and substantial increase in dietary fiber may lead to bloating and cramping. Concurrently increasing fluid consumption while incorporating more fiber can also help mitigate these side effects.

Fiber Nourishes Beneficial Gut Bacteria

The human body plays host to a vast number of bacteria, outnumbering the body’s cells at a ratio of 10 to 1. These bacteria inhabit various regions, including the skin, oral cavity, and nasal passages, with the predominant population residing within the gut, predominantly the large intestine. In the intestine, approximately 500 to 1,000 distinct bacterial species, totaling approximately 38 trillion cells, coexist. These inhabitants of the gut are collectively known as the gut flora.

This dynamic isn’t negative; indeed, it establishes a mutually advantageous connection between individuals and certain bacterial residents within the digestive system. Individuals offer sustenance, accommodations, and a secure environment for these bacteria, and in return, the bacteria manage tasks beyond the natural capabilities of the human body.

Among the diverse bacterial varieties, certain ones are of paramount importance for various facets of health, encompassing aspects like weight regulation, blood sugar management, immune system performance, and even cognitive function. The question that may arise is how this connects with dietary fiber. Comparable to any living organism, bacteria require nourishment to sustain their vitality and function.

However, a predicament arises as most carbohydrates, proteins, and fats are absorbed into the bloodstream before reaching the large intestine, providing little sustenance for the gut flora. This is where fiber emerges as a crucial factor. Unlike human cells, which lack the necessary enzymes to metabolize fiber, the intestinal bacteria possess these essential enzymes and can digest a considerable portion of these fibers.

This delineates the principal rationale behind the importance of certain dietary fibers for health. They serve as nourishment for the “beneficial” bacteria within the intestines, essentially functioning as prebiotics. Through this mechanism, they stimulate the proliferation of these advantageous gut bacteria, which can yield a myriad of favorable health effects.

These friendly bacteria generate vital nutrients for the body, including short-chain fatty acids such as acetate, propionate, and butyrate, with butyrate being of primary significance. These short-chain fatty acids can provide nourishment to colon cells, consequently reducing gut inflammation and ameliorating digestive disorders, including irritable bowel syndrome, Crohn’s disease, and ulcerative colitis.

As a consequence of bacterial fermentation of fiber, gas production occurs. This is why high-fiber diets may induce flatulence and abdominal discomfort in some individuals. Over time, these side effects typically subside as the body adapts.


  • Both, soluble and insoluble fibers are essential for a healthy body.
  • Consume 25-35g of fiber a day.
  • Naturally occurring fibers are superior to supplements.
  • Adequate amount of fiber can reduce the risks of heart disease, diabetes, cancer, diverticular disease and constipation.
  • The gut flora needs fiber.

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