It’s long been known that the general intestinal health of the population in countries where large quantities of plant-based foods are consumed is extremely good. Numerous disorders of the lower digestive tract which occur with high frequency in the modern world virtually do not exist there. The reason for this was previously unknown, but it was obvious that their plant-based diet played an important role.
In the mid-1990s, doctors and nutritionists discovered that certain soluble dietary fibers such as inulin, oligofructose and FOS (fructooligosaccharides) lead to significant positive changes in the composition of the bacteria in the intestine. They had discovered prebiotics.
What are prebiotics?
Prebiotics are a special form of fiber. They are fermented by the good, health-promoting intestinal bacteria in the large intestine and are used as a food source. Prebiotics thus stimulate the growth of good, beneficial lactic acid bacteria and bifidobacteria in the intestine. This improves the ratio of good to bad bacteria in favor of beneficial bacteria.
Some of the intestinal bacteria produce not only lactic acid, but butyric acid as well. This ensures that the intestinal wall is well nourished so that the intestine can perform its tasks optimally.
A well-functioning intestinal wall provides an effective barrier against the penetration of toxins and pathogens. The natural intestinal flora is also prevented from penetrating into the tissue. Nutrients and minerals can also be absorbed more efficiently from food.
Hormones are created in the intestinal wall which control the appetite and have a positive effect on the nervous system and the immune system. Butyric acid also ensures that the intestinal environment remains acidic, thus reducing the activity of pathogenic enzymes.
If the level of butyric acid falls too much, the intestinal villi and the intestinal mucosa become thinner. This increases the risk of chronic inflammatory diseases and, consequently, of colon cancer.
If too little prebiotic fiber is eaten, good intestinal bacteria are starved and are displaced by illness-causing, putrefying intestinal bacteria. Dysbacteria develops, since the intestinal flora is knocked out of balance in favor of bad bacteria.
The first signs of dysbacteria are digestive problems, irregular bowel movements and increased flatulence. If the intestinal flora remains out of balance for a longer period of time, this can lead to the development of numerous chronic and degenerative diseases.
Prebiotics, therefore, contribute to the natural balance of the intestinal flora thanks to the growth of good intestinal bacteria. This also increases the activity of health-promoting lactic acid bacteria and bifidobacteria, which has a positive effect on overall health and wellbeing.
Which forms of prebiotic fibers are there?
All plants contain a combination of soluble and insoluble prebiotic fibers, but in different proportions. The two fibers are not digested in the stomach or in the small intestine. Instead, they migrate undigested through to the large intestine.
Soluble dietary fibers are, as the name implies, soluble in water. They are fermented in the intestine by anaerobic bacteria and converted into healthy gases and acids which promote the growth of the good bacteria in the lower digestive tract. These bacteria have a positive effect on various basic body functions as well as overall health.
Insoluble dietary fibers, on the other hand, are not soluble in water, but are just as important as soluble fiber when it comes to health and well-being. Insoluble dietary fibers are further divided into two types – fermentable and non-fermentable insoluble dietary fibers. Non-fermentable dietary fibers are primarily used as fillers. However, they have the ability to bind water and thereby contribute to a more gentle, regular bowel movement.
Fermentable insoluble fibers – such as resistant starch – are equally healthy as the soluble dietary fibers as a source of nutrients for the good intestinal bacteria in the large intestine. Resistant starch combines the advantages of insoluble and soluble dietary fibers and produces the same effect as the latter two in the large intestine. They also help you to stay ‘full’ longer because they are not digested as quickly.
Where is prebiotic dietary fiber found?
Prebiotic fiber is found in many fruit and vegetable varieties, such as apple peels, almost ripe bananas, leeks, onions and garlic, asparagus, whole grain cereals, parsnips, Jerusalem artichokes, salsify, chicory roots, potatoes and legumes.
Although this makes it sound as if you could eat sufficient prebiotic fiber, this is unfortunately not true. The fact, that the content of prebiotic fibers in all of these foods is only 1 to 2 grams per meal, makes it extremely difficult to ingest sufficient amounts of dietary fiber.
We humans should consume at least 25 grams of dietary fiber daily to maintain the health of our intestinal flora. For many of us, consuming this amount of food with prebiotic fiber is not possible.
The good news is that the use of a prebiotic fiber in powder form can easily replace the dietary fiber missing in our diet. These powders have a neutral flavour, which allows them to be simply added to water, cereal or other foodstuffs in order to benefit from their many advantages.
What effect do prebiotics have?
Prebiotic fibers are fermented in the large intestine by intestinal bacteria. The resulting metabolic products serve as a source of nutrients for the good intestinal bacteria. In the same way as good probiotics multiply if there is a sufficient presence of prebiotic fibers, bad intestinal bacteria, which mainly feed on simple sugars, are kept in check.
The sufficient intake of prebiotics has many advantages for our health:
- improves the growth and activity of the good, protective gut bacteria
- reduces the growth of the bad bacteria
- supports better total digestive health
- improves the intestinal function and promotes softer and regular bowel movements
- improves the barrier function of the intestinal wall
- increases the absorption of calcium and magnesium
- improves bone density, especially in younger adolescent
- supports a strong immune function
- lowers stress response
- promotes a better hormonal balance
- reduces cholesterol levels
- lowers autoimmune reactions
- eliminates smelly flatus and gas
- lowers the risk for obesity and weight gain
- improves satiety and appetite control
- reduces the risk of inflammation and associated cardiac diseases
- reduces intestinal permeability and leaky gut syndrome
Do prebiotics have side effects?
The ingestion of larger amounts of prebiotic fibers can initially lead to bloating. This is especially the case when there are not enough intestinal bacteria which use the dietary fiber as a source of food.
Consequently, at the beginning you should only consume a small amount of dietary fiber each day and slowly increase it depending on how you feel. This will give the intestinal bacteria an optimal chance to multiply, which will also result in better tolerance when increasing the amount of prebiotic fibers consumed.
Do prebiotics always have to be taken with probiotics?
Prebiotic fibers are the ideal food for beneficial, useful intestinal bacteria. If sufficient intestinal bacteria are present in the intestine, the supply of prebiotics suffices to stimulate the growth of the health-promoting intestinal bacteria.
If the intestinal bacteria have been decimated due to the use of antibiotics, or there is an excess of illness-causing intestinal bacteria for some reason, both a high-quality probiotic as well as a prebiotic should be ingested.
The 8 most important benefits of prebiotics
1. Prebiotics for a healthier gut and better digestion
Prebiotics stimulate the growth of useful bacteria (probiotics) which reside in the intestinal flora. They help to control harmful bacteria and toxins, which in turn has a positive effect on one’s health, including improved digestion.
Research has shown that eating a diet high in prebiotic dietary fiber can increase the number of many probiotic microorganisms, including Lactobacillus rhamnosus GG, L. reuteri, bifidobacteria, and certain strains of L. casei or the L. Acidophilus group.
A significant advantage of the useful intestinal bacteria is that they use the dietary fiber in the food we eat and which would otherwise be indigestible as a source for their survival. They produce short-chain fatty acids, including butyric acid.
This provides for a healthier intestinal mucosa and regulates electrolyte levels in the body, including sodium, magnesium, calcium and water. These components are very important for good digestion as they stimulate bowel movements and prevent diarrhea.
A change in the composition of the intestinal flora can be one of the many factors that play a role in the development of inflammatory intestinal diseases or irritable bowel syndrome.
A report in The Journal of Nutrition published in 2012 states that prebiotics, together with probiotics, can help to treat the following digestive problems:
- Diarrhea (which is a common consequence after taking antibiotics)
- Certain intestinal infections and chronic disorders, such as Crohn’s disease and ulcerative colitis
- Inflammatory bowel disease
- Symptoms of irritable bowel syndrome (IBS)
- Leaky gut syndrome
2. Prebiotics stimulate bowel movements
Prebiotic fibers can promote consistency and stool frequency in various ways. On the one hand, the insoluble fiber in the large intestine serves as a filler. At the same time, it has the ability to bind water, leading to increased stool weight and an accelerated passage through the intestine. Both leads to a softer, regular bowel movement.
Soluble dietary fibers serve as a source of food for the good intestinal bacteria, which means they can multiply better. In turn, the intestinal flora establishes a healthy equilibrium. The health-promoting intestinal bacterial produce short-chain fatty acids, which lower the pH in the intestine. This also results in a positive change to stool consistency and stimulates peristalsis of the intestine.
3. Prebiotics strengthen the immune system
Many studies in humans have shown that the consumption of prebiotic fibers has a significant effect on the composition of the intestinal flora, thereby strengthening the immune system. At the same time, the concentration of carcinogenic enzymes and putrefactive metabolic products in the intestine was shown to decrease.
A report in The British Journal of Nutrition has demonstrated that prebiotics help improve stool quality (frequency and consistency) and reduce the risk of infection, allergic symptoms and gastroenteritis. In general, overall health improved with prebiotics.
Prebiotics and probiotics strengthen the immune system because they promote our ability to absorb important nutrients and access the minerals in our food. They also effectively reduce the pH of the intestine, which prevents the growth of potentially harmful bacteria.
Strengthening the immune system also benefits individuals via the prevention and treatment of urinary tract infections, vaginal pelvic infections, digestive disorders, colds and flu, cognitive disorders and even cancer, including colorectal cancer.
Intestinal cancer is often associated with toxic stress, whereby a pathological composition of the intestinal flora plays a possible role. Numerous studies show a reduction in the frequency of tumors and cancer cells following the consumption of special prebiotic foods.
4. Prebiotics reduce inflammation
Prebiotics can help reduce inflammation. Inflammation is one of the primary causes of many diseases, including cardiovascular disease, which is the most common cause of death.
People who eat more prebiotics, and generally consume a diet which is higher in fiber, generally have healthier cholesterol levels and a reduced risk of cardiovascular disease.
Prebiotics and probiotics are thought to contribute to the improvement of metabolic processes associated with both obesity and type 2 diabetes. It also appears that a healthier intestinal flora is able to prevent autoimmune responses. This also better regulates hormonal functions and immune functions, which have control over how and where the body stores fat.
5. Prebiotics and heart diseases
Eating food with a high proportion of prebiotics can reduce glycation – which increases free radicals and causes inflammation and thus increases the risk of cardiovascular disease.
Prebiotics have a so-called hypercholesterolemic effect that improves the body’s ability to ward off the risk of ischemic heart disease and autoimmune diseases (such as arthritis). Another advantage of prebiotics is that they balance the electrolyte and mineral level in the body, including potassium and sodium levels, which are responsible for regulating blood pressure.
6. Prebiotics stimulate weight lossStudies show that certain prebiotic foods improve energy levels, regulate the feeling of fullness when eating, and promote weight loss. In fact, an increased intake of all kinds of dietary fibers is associated with lower body weight and lower risk for obesity.
A 2002 study published in "The British Journal of Nutrition" showed, that prebiotic foods contribute to the feeling of fullness or “satiety”, prevent obesity, and promote weight loss. The effects of prebiotics on hormone levels are linked to appetite control and are supported by studies which show, that animals, that eat prebiotics produce less ghrelin, which signals the brain that it is time to eat.
7. Prebiotics promote bone health
A study published in 2007 in "The Journal of Nutrition" found that prebiotics promote mineral absorption in the body, including of magnesium and possibly iron and calcium. All these minerals are essential for maintaining bone strength and preventing bone fractures and osteoporosis.
One study shows that ingesting only eight grams of prebiotics daily has a significant effect on the body’s calcium uptake, resulting in increased bone density.
8. Prebiotics and their effect on hormones and mood
Research is showing more and more clearly, that mood-related disorders such as anxiety or depression are highly related to intestinal health. Mood as well as hormonal balance are influenced by a combination of factors which among others depend on the state of one’s intestinal bacteria.
Nutrients from food are absorbed and converted via the intestine. They ultimately serve to support neurotransmitter functions that produce hormones (such as serotonin), which in turn control mood and help relieve stress.
The ultimate trigger of a mood-dependent disorder could be a series of neurotransmitter malfunctions in the parts of the brain that are responsible for fear and other emotions. These transmissions depend in part on the health of the intestinal flora. Thus, when the intestinal flora ends up out of balance, other biological pathways, including hormonal, immunological or neuronal transmission, do not work properly.
Recent studies have shown, that prebiotics have a significant neurobiological effect on the human brain, including the reduction of cortisol levels and the body’s stress response.
A study published in "The Journal of Psychopharmacology" in 2005 investigated the effects of two prebiotics on the excretion of the stress hormone cortisol and the emotional impact in healthy adult volunteers.
After the volunteers received either one of two prebiotics or a placebo daily for three weeks, the group taking prebiotics showed a positive change in cortisol levels when taking an emotional test and a reduced sensitivity to negative as opposed to positive information.