• Fiber is found mostly in cereal grains, seeds, vegetables, and fruits
  • Fibers help the process of toxic waste elimination
  • Eating  fibers can reduce the risk for diabetes, breast cancer, and colon cancer

Fibers are the part of food that cannot be digested by our gastrointestinal enzymes but still have many health benefits.There are two types of fibers: soluble and insoluble.

Soluble fiber dissolves in water. After absorbing water, soluble fiber becomes gelatinous; it goes through the digestive tract and gets fermented by gut bacteria. This helps reducing the level of cholesterol and low-density lipoproteins (LDL) known as bad cholesterol. Moreover, it regulates the rate of sugar absorption, especially useful for people with diabetes (1).

Insoluble fiber,unlike soluble fiber, does not dissolve in water. Its chemical structure doesn’t change as it goes through the digestive tract. It plays an important role in controlling acidity level in the intestines preventing gut bacteria from releasing toxins that may lead to colon cancer. Most importantly, it promotes regular bowel movements preventing constipation (1).

Figure 1. Examples of high-fiber foods. Image adapted from (2).

Fiber binds with minerals, including calcium, magnesium, iron and zinc, and can interfere with the ability of body to absorb these essential nutrients. According to a research the optimal amount of daily fiber intake is 25-29 grams (3). By comparison, adults in the United States consume 15 grams per day (4). However, it is important that the levels of fiber intake is monitored as eating too much fiber may lead to  nutrient deficiencies (5). Read below 5 research-based fiber health benefits:

1. Increasing daily fiber intake reduces the risk for colon cancer – During a research done from O’Keefe, S. J. D. et al (2015) with African Americans and rural Africans, it was indicated that diet plays a major role in increasing the risk for development of colon cancer (6). There is a major difference between the daily diet of African Americans (low in dietary fiber e.g.12 g per day) and rural Africans  (high in dietary fiber e.g. 55 g per day) correlating with colon cancer incidence (higher among African Americans) (7). According to the research there is a 10% reduction in the risk of developing colon cancer for every 10 g increase in daily fiber intake (8).

2. High-fiber diet reduces the risk for asthma – A recent study published in Nature Medicine in 2014  suggests that a high-fiber diet after being metabolized by gut microbiota, promotes reduction of airway allergic inflammation (9). This study was done in mice given a high-fiber diet, digested from gut microbiota giving circulating short-chain fatty acids (SCFAs) (10).It is these SCFAs that bare the protective effect by affecting the development of immune cells in the bone marrow once they enter the bloodstream (9). These immune cells alter the severity of allergic inflammation such as asthma (11).

3. Boosting daily fiber intake reduces the risk for osteoarthritis – Previous studies were limited to addressing the risk of osteoarthritis in obese people to the extra strain they put on their joints (e.g. the knees). Recent studies suggest that high-fat diet promotes changes in gut microbiota (12). This is demonstrated by increased number of inflammation-promoting microbes. According to research results published on April 19, 2018, in JCI Insight, Bifidobacterium pseudolongum (a microbe in the gut microbiota) ferments oligofructose (a dietary fiber found in bananas and other plants) and reduces inflammation with its byproducts (13). This system-wide reduction of inflammation may result in reduced risk for development of osteoarthritis (14).

4.High-fiber diet decreases the risk for breast cancer – A research done at suggests that breast cancer risk was 12%-19% lower among women who ate more dietary fiber in early adulthood and 24% lower before menopause among women who ate more dietary fiber during adolescence (15).10 grams of daily fiber intake during early adulthood, that is equivalent to one apple and two slices of whole wheat bread, results in decreased cancer risk for 13% (16).

5. Fibers are the superfood against diabetes – A fiber-based diet also may contribute to reduction of T cell–dependent autoimmune diseases such as type 1 diabetes (17). A recent study published in Nature Immunology in 2017 found that blood and fecal concentrations of acetate and butyrate (two microbial metabolites created by gut microbiota by fiber digestion) enhances protection against type 1 diabetes by improving the integrity of the gut lining, which reduces pro-inflammatory factors (18). Our gut being such a complex system it is hard to believe that it is created only to make sure things move out of our colon. In fact, by some scientists it is considered as our second brain influencing our mood, immune system and long-term health (19). That is why our daily healthy diet is a very important component that enhances our gut (with its microbiota) influence on our immune system and long-term well-being.

COPYRIGHT: This article is the property of We Speak Science, a non-profit institution co-founded by Dr. Detina Zalli and Dr. Argita Zalli. The article is written by  Rina Mehmeti, University of Prishtina, Kosovo.


  1. https://www.medicalnewstoday.com/articles/146935.php
  2. https://www.healthychildren.org/English/healthissues/conditions/abdominal/Pages/Constipation.aspx
  3. https://www.eatrightpro.org/-/media/eatrightpro-files/practice/position-and-practice-papers/position-papers/healthimplicationsfiber.pdf
  4. https://www.eatrightpro.org/-/media/eatrightpro-files/practice/position-and-practice-papers/position-papers/healthimplicationsfiber.pdf
  5. https://www.medicalnewstoday.com/articles/324153.php
  6. https://www.foundmyfitness.com/news/stories/xydwbf
  7. https://www.nature.com/articles/ncomms7342#results
  8. https://thefoodmedic.co.uk/2019/02/dietary-fibre-bowel-cancer-risk/
  9. https://www.nature.com/articles/nm.3444
  10. https://www.medicalnewstoday.com/articles/270827.ph
  11. https://www.foundmyfitness.com/news/stories/v1lp1u
  12. https://www.foundmyfitness.com/news/stories/xt8b9h
  13. https://insight.jci.org/articles/view/95997
  14. https://www.nih.gov/news-events/nih-research-matters/dietary-fiber-protects-obese-mice-arthritis
  15. https://www.sciencedaily.com/releases/2016/02/160201084354.htm
  16. https://www.foundmyfitness.com/news/stories/kbtcro
  17. https://www.foundmyfitness.com/news/stories/nmcwmj
  18. https://www.nature.com/articles/ni.3713
  19. https://www.scientificamerican.com/article/gut-second-brain/