Food fibers

Dietary fiber, or simply fiber, are key elements for a healthy and balanced diet, and are normally of vegetable origin.
Fiber can be found in more or less all plant-based foods, however, there are differences in amounts between each plant. You will find below which foods are high in fiber.
Dietary fibers are not assimilated by the human body, because they are not digested by digestive enzymes. Dietary fiber contains no calories , as it is not metabolized.

chemical structure

In terms of chemical structure, fibers are polysaccharides, also called carbohydrates or complex sugars. However, lignin (soluble fiber) has a different structure. This chemical structure makes digestion possible by digestive enzymes, which is not the case for other sugars.

Soluble and insoluble fiber

We can distinguish between soluble and insoluble fiber. Both have beneficial health properties, with some differences.

fiber – Soluble fiber dissolves in water. Examples are pectin (found in apples), gum (found in beans or cereals) and beta-glucan (found in oats).
– Soluble fiber, which are also called viscous fibers, can be fermented in the large intestine. In other words, bacteria in the large intestine are capable of breaking down soluble fiber.

Insoluble fiber
– Insoluble fiber does not dissolve in water. Examples are cellulose (present in vegetables such as carrots , whole wheat, beans), hemicellulose (in cereals) and lignin (stems or leaves of some plants).
– Insoluble fibers, which are also called non-fermentable fibers, cannot be degraded or fermented by intestinal bacteria.

Foods rich in dietary fiber

Soybeans , corn, brown rice, apples, strawberries, oats, broccoli (eg 3 flowers), prunes, barley, whole wheat, apricots, artichokes , raspberries, flax seeds  (linseed), some cheeses and yogurts are rich products in fibers.

Read more: 12 Foods Rich in Dietary Fiber

effect of fibers

Fiber promotes bowel movements and has a regulatory effect. They are especially recommended in cases of  constipation . There is an increase in the volume of stool and the amount of water absorbed. In fact, fiber accumulates water and fills the stomach faster.

Fibers, particularly insoluble ones, swell with water and have a positive effect on intestinal transit.

The person has a quick feeling of satiety, which reduces hunger and has a beneficial function in weight loss. However, fiber requires a person to drink a lot of water for its effect to be seen.

Soluble fiber is especially effective in lowering cholesterol (bad or LDL cholesterol).

It is interesting to note that fiber has an influence on the absorption of certain nutrients such as sugars, fats, vitamins, etc.

According to a study published in the French journal Science & Vie (July 2014 edition), fibers are transformed in the colon into acetate, a molecule that causes the feeling of satiety.


– Dietary fiber is indicated in cases of constipation , diverticulitis , hemorrhoids , and also in weight maintenance (highly recommended in diets). Dietary fiber also has a preventive effect on stroke (7 g or more of fiber per day lowers the risk by 7%), colon cancer and high cholesterol .

– Fibers have shown a preventive effect on type 2 diabetes . In a study carried out by Harvard University in the USA, scientists showed that eating brown rice could have a positive effect against this form of diabetes.

– A study published at the end of April 2014 by researchers from Harvard, in the United States, showed that fiber intake increases life span among people who have suffered a myocardial infarction (heart attack) . Individuals eating very high-fiber foods saw their risk of having a heart attack and stroke decrease by about 25%, compared to those who ate little fiber. Cereal fibers showed a more significant decrease in cardiac risk than other foods such as fruit.

– According to Swiss researchers from the Center Hospitalier Universitaire de Lausanne, eating fiber-rich fruits and vegetables can have a preventive effect against allergic asthma by changing the microbial flora. In pregnant women, this protection can spread to their newborns.

– According to an American study conducted by Columbia University, published in February 2016 and involving 26 participants, those who consumed foods rich in fiber and low in sugars and saturated fats had better quality sleep and the time required to fall asleep decreased in approximately 15 minutes (from 29 to 17 minutes).

Aging and Fiber Intake
– An Australian study published in June 2016 in the online version of the Journal of Gerontology by scientists at the Westmead Institute in Australia showed that eating large amounts of fiber from bread, cereals and fruit decreased age-old disease and disability and increased life expectancy.

– A high intake of fiber mainly from food can surprisingly help with the treatment of gout .
Researchers have shown in an experiment with mice that a high-fiber diet decreases inflammation in cases of gout. Gout is an inflammatory disease that, as seen above, is mainly caused by the accumulation of sodium urate crystals. The effect of fiber on sodium urate is indirect. According to researchers, fibers favor the production of short chain fatty acids (short chain fatty acids or SCFAs) from intestinal microorganisms. The positive outcome for gout is that these fatty acids lead to apoptosis (death) of neutrophils and reduce inflammation at the joint level. This study carried out by the Federal University of the State of Minas Gerais, Brazil, was published in January 2017 in the printed version of the specialized magazineJournal of Leukocyte Biology . As this study was performed in rats, further studies are needed to verify whether these results are reproducible in humans.

– A significant consumption of fiber can help to lose weight, especially in case of overweight and obesity , but there are differences between each individual.

– A study conducted on mice showed that dietary fiber is a protective agent against obesity and metabolic syndrome by promoting the growth of “good” bacteria in the colon. Supplementing a high-fat diet with fiber inulin can help reduce weight loss and restore gut microbiota levels. This study was published on December 21, 2017 in the scientific journal Cell Host & Microbe (DOI: 10.1016 / j.chom.2017.11.003).

fiber side effects

Excessive intake of dietary fiber can lead to bloating ( flatulence ), diarrhea or in rare cases, an intestinal blockage (especially if the person does not drink enough water).


In some diseases of the digestive system, such as Crohn’s disease , fiber intake is not adequate. Talk to your doctor.

Recommended daily amount of fiber

According to the American Association of Cardiologists (English: American Heart Association) it is recommended to consume at least 25 grams of fiber per day. This can be achieved by consuming the amount of, for example, 6-8 servings of grains and 8-10 servings of fruits or vegetables every day. It should be noted that it is not easy to achieve this daily goal.

The World Health Organization is more precise and believes that women should eat 25 grams of fiber a day and men 30 to 40 grams a day.

In Brazil, the Ministry of Health recommends the consumption of 25 grams (minimum) of fiber per day.

Fiber intake tips

1. If your diet is low in fiber (as in diets high in meat, dairy, etc.) and you would like to eat more fiber, be careful not to radically change your diet overnight. You can gradually switch to a high-fiber diet by consuming more grains, for example fruit or vegetables. Too sudden a change in diet can lead to side effects.
Cereals may have the greatest effect, so it’s best to start with a diet rich in fruits and vegetables, and gradually incorporate cereals.

2. Drink plenty of water! The more you consume the more fiber, the more water you should drink to promote intestinal transit.

3. Wholegrain foods usually contain more fiber (sometimes 4 times more), so choose wholegrain pasta, brown rice, wholemeal bread, etc.

– A Danish study conducted in 2017 showed that a fiber-rich diet, such as the Nordic Diet (“New Nordic Diet”), is not always effective for weight loss. Its success depends on a particular combination of gut bacteria in the person carrying out the dietary regimen. In other words, some people have a combination of gut bacteria that prevent fiber from being effective in weight loss. Better identification of certain intestinal bacteria (enterotypes), thanks to tests performed on stool extracts, should make it possible to predict whether or not a high-fiber diet is effective in losing weight. This study carried out by the University of Copenhagen under the direction of Mads Hjorth and Arne Astrup was published in the scientific journal International Journal of Obesityon September 8, 2017.

Also Read: Eat More Fruits and Vegetables a Day to Live Longer

Jeanne Kenney
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I’m a stylist trainer, a content creator, and an entrepreneur passion. Virgo sign and Pisces ascendant, I move easily between my dreams, the crazy world I want, and my feet on the ground to carry out my projects.

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