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What Is The Role Of Dietary Fiber on Gut Health?

Growing evidence and studies show that sufficient fiber intake in your daily diet will benefit your digestion and reduce the risk of chronic diseases. Also, a research study used 24-hour recalls from participants and found that the relationship between food and microbial composition was stronger than the relationship between nutrients and microbial composition. Apart from genes, environment, and medications, a high fiber diet plays a large role in determining the kinds of microbiota that live in the colon. All of these create microbiomes unique from person to person.

Dietary fiber - known as roughage or bulk, includes plant foods. Fats, proteins and carbohydrates break down and are absorbed, but the fibre isn't digested by our body. It passes through the stomach, intestines and colon. Consuming a diet of high fibre improves the nutritional niches in the intestine, allowing good bacteria to expand.

Fibre is majorly classified into:-

  1. Soluble fiber waters down to form a gel, which helps in reducing cholesterol and blood glucose levels. Steel-cut oats, beans, green leafy vegetables, apples, citrus fruits, carrots, barley and psyllium are examples of soluble fiber.

  2. Insoluble fiber promotes the passage of food through the digestive system and increases the stool bulk, which helps those who struggle with constipation or irregular bowel movements. Green beans, potatoes, whole wheat flour, wheat bran, beans, nuts and vegetables, such as cauliflower, are excellent sources of insoluble fiber. To receive the greatest health benefit, include a wide variety of high-fiber foods in our day-to-day meal routine

Dietary fibers are broken down and fermented with the help of enzymes from microbiota abundantly found in the colon. As a result of fermentation, Short chain fatty acids (SCFA) are released and this helps in lowering the pH level of the colon, which determines the type of microbiota that survives in the acidic environment. Gut microbiota supplies vital components for the fermentation of non-digestible dietary fibres and intestinal mucus, and this fermentation helps and supports the growth of microbes which forms short-chain fatty acids (SCFAs) and gases.


The fermentation of fibers leads to the formation of short-chain fatty acids (SCFA) which are utilized by the body as a nutrient source by playing a vital role in muscle functioning and the prevention of metabolic diseases, cancers like colon cancer and bowel disorders.


The 3 main Short chain fatty acids are acetate, propionate, and butyrate.

  • Acetate— It is the most abundant short-chain fatty acid and an essential metabolite for the growth of microbiomes which gets into the peripheral tissues and is used for cholesterol metabolism and lipogenesis.

  • Butyrate - It is formed when the good bacteria in our gut help our body break down the dietary fibre in the colon. It also works as an energy source for human colonocytes, which induces apoptosis of colon cancer cells, which will activate intestinal gluconeogenesis, having beneficial effects on glucose and energy homeostasis.

  • Propionate- It is an important microbial fermentation metabolite in our gut. It is transported into the liver, where it regulates gluconeogenesis and satiety signalling via interaction with the gut fatty acid receptors.

Research conducted on short-chain fatty acids has shown extensive importance in health such as vitalizing immune cell activities and balancing normal blood levels of glucose and lipid profiles.

Foods which increase the levels of short-chain fatty acids are known as indigestible carbohydrates and fibers like- inulin, resistant starches, gums, pectins, and fructooligosaccharides. These are known as prebiotics and they feed our beneficial microbiota, for example- apples, banana, berries, flaxseeds, legumes like peas, beans etc

And probiotics are foods, which contain live bacteria. Examples are yoghurt, some cheeses and fermented foods like sauerkraut, kefir etc.

According to the Academy of Nutrition and Dietetics and Institute of Medicine, the total daily recommended for women is 25gms fiber per day and for men to be consumed 38 gms of fiber per day. For adults above 50 years, women should aim for 21 gms and while men should target 30 gms per day.

Your gut’s microorganisms help in maintaining the integrity of the gastrointestinal lining that keeps you healthy. Fiber provides nutrition to our gut bacteria and they don’t turn into your gut lining for food. Also, fiber and your gut bacteria stimulate mucus production helping in fortifying your gut’s protective barrier.

Thus, they promote the growth of “good” gut bacteria, which can have positive effects on health.

Tips to improve level up your fiber intake –

  • Kick start your day with a wholesome breakfast by choosing high-fiber cereals like whole grains, whole wheat flour, brown rice, barley, burglar wheat, bran, steel cut oats etc

  • Legumes – include beans, peas, lentils, whole legumes and lentils with skin, kidney beans etc which are excellent sources of fiber.

  • More vegetables – include a wide variety of vegetables into your daily routine as they are rich in fiber and vitamins and minerals as well. Try to have a minimum of 5 servings per day. Such as broccoli, green leafy vegetables such as spinach, amaranth, drumstick leaves, kale leaves etc

  • Fruits- Include a minimum of 2 servings of fruits per day. Switch with fruits instead of sweets. And make sure to have fruits as such instead of fruit juices.

  • Dried fruits – dry fruits such as figs, prunes, and dates can improve your intake of fiber recommendations. Sunflower seeds and almonds each have more than 3 grams of fibre per serving. Raw or plain-roasted nuts are better compared to the packaged varieties which are usually fried in oils that can add extra, unnecessary calories. Include 2 handful servings of dry fruits per day. It also contains phenolic antioxidants which have numerous health benefits.

  • Last but not least include adequate water intake, fiber works best when it absorbs water.


3. - American society for Microbiology

5. - Academy of Nutrition

6. - American Society of Nutrition

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