There is an old folk saying that health begins in the intestines. In the last century, it became known that symbiotic microorganisms play a major role in the intestines. However, their role is not limited to intestinal health. It extends to our general health. Beneficial intestinal bacteria help fermentation, protect against pathogenic bacteria, and stimulate the immune system’s development. Good microorganisms or “probiotics” are used for this purpose. They are often combined with prebiotics, which supports probiotics. Preparations from both cultures are called synbiotics. They are used when the balance between the types of bacteria in the intestines is disturbed (dysbiosis) and for preventing and treating diseases. Here you will learn everything you need to know about probiotics and prebiotics, from the area of application to clinical uses.
Probiotics: beneficial bacteria in the diet or supplements, the consumption of which strengthens or improves the intestinal flora and has a beneficial effect on the microbial balance in the intestines. The World Health Organization (WHO) defines probiotics as: “Living microorganisms that, if given in sufficient quantities, bring health benefits to the host organism.” Probiotics (“for life”) owe their name to antibiotics (“against life”).
Prebiotics: substances that serve as food for beneficial microbes and help maintain health by multiplying them.
Synbiotics: Dietary supplements that form colonies and contain a combination of prebiotics and probiotics.
Dysbiosis: qualitative and quantitative changes in the intestinal flora, its metabolic activity, and local distribution; disturbed balance between bacterial species in the intestines, as a result of which pathogenic germs negatively affect the health of the host, and systemic diseases are promoted.
Microbiota: intestinal flora. Whole microorganisms (bacteria, yeasts, and fungi) in the intestines are crucial for their host’s immune, hormonal, and metabolic homeostasis.
The idea of using probiotics came from the Russian Nobel Prize winner Ilya Mechnikov (1845-1916), the father of natural immunity, who in the early 20. century advocated using lactic acid-producing bacteria, such as those in yogurt, kefir, and sour milk, to displace harmful bacteria and thus prolong life. His assumption was based on the fact that people have been consuming large amounts of fermented foods such as sauerkraut, yogurt, and cheese for centuries. This fermented food contains nutrients and bacteria that positively affect our health. Countries like Bulgaria, where at least half a liter of yogurt is eaten per person per day, are known for a high percentage of people reaching above-average age (over 100 years). Metchnikoff’s theory was rediscovered in 1989. years and since then, she has been given medical attention. To manipulate the composition of the intestinal flora in favor of a potentially better medicinal community of bacteria, the concept of prebiotics was introduced in 1995.
The digestive tract’s main functions are absorption and digestion of food, absorption of nutrients, and removal of waste materials. The gastrointestinal tract also plays an important role in the immune system. With 250 to 400 m2, it is the second-largest contact area (after the respiratory tract) between the organism and the environment and, therefore, one of the primary ways we are exposed to pathogens. Therefore, the largest part, estimated at more than 70%, are cells that produce antibodies that are located in the intestinal mucosa (GALT from the English gut-associated lymphoid tissue: intestinal-associated lymphoid tissue).
Our body has been colonizing many microbes since early life. This colonization process begins when a sterile baby moves through the birth canal and receives an oral inoculation from the mother’s vaginal microbiota. The result is a complex and dynamic ecosystem in the gastrointestinal tract with diverse microorganisms. These microorganisms belong to the residential intestinal microbiota, or transient flora introduced from the environment by food intake and temporarily remain in the intestine. The growth of microorganisms in the small intestine depends on the rapid passage of the contents (3-5 hours). Since bile and pancreatic juice’s secretion is limited, most microbiotas reside in the large intestine. Scientists disagree about the number of bacteria types in the gut because many of them have never been isolated. Although there are large differences between individual people, the number of bacterial species found in the intestines varies from 500-1000 with a total weight of 1-2 kg. They are predominantly strict anaerobes.
The role of intestinal bacteria
The intestinal flora’s main role is to use fermentation to extract energy from dietary carbohydrates that are not digested in the upper intestine.
In addition to its role in fermentation, the colon microbiota contributes to host health in several ways:
Barrier function: They represent a barrier that prevents the entry of pathogenic bacteria into the gastrointestinal tract
Protective function: Together with the intestinal immune system, resident bacteria can perform a protective function by secreting non-specific antimicrobial substances such as short-chain fatty acids or hydrogen peroxide while producing other toxins with a very narrow killing range, such as bacteriocins.
Intestinal bacteria participate in the synthesis of vitamins B – B1, B2, B5, B6, biotin (B8), folic acid (B9), B12 – and vitamin K.1
Xenobiotic metabolism (foreign chemical compounds such as pesticides and drugs)
Bacterial balance in the gut
During evolution, some symbiotic associations of hosts and bacteria in the human intestine developed. By approximately 3 years of age, the intestinal microbiota has reached a composition and diversity similar to that of adults. Healthy microbiological flora is characterized by a good balance between symbiotes (microorganisms with health-promoting properties such as Lactobacillus and Bifidobacterium), commensals (microorganisms that are neither good nor bad for the health of the host) and pathobionts (potential pathogens such as Clostridium). Although our intestinal microbiota is relatively stable, it is subject to changes through diet, pregnancy and other environmental influences during our lifetime. Illness, mental and physical stress, travel or the use of medications such as antibiotics can also lead to an imbalance in our intestinal flora, dysbiosis.
Dysbiosis is defined as qualitative and quantitative changes in the intestinal flora, metabolic activity, and local intestinal flora distribution. Antibiotics that upset the normal flora’s balance can encourage infection with exogenous pathogens and overgrowth with endogenous pathogens. Dysbiosis gives a strong association to the pathogenesis (occurrence and development of the disease) of many inflammatory diseases and chronic inflammatory bowel disease or IBD inflammatory bowel disease, autoimmune diseases, infections, and even cancer (breast or colon). To treat dysbiosis, researchers are currently looking at not only oral probiotics but also stool transplantation (fecal microbiome transfer, FMT) to treat intestinal flora with transplanted microbes (donor flora) reception to return RS to balance. Although this is an interesting development, FMT is beyond this article’s scope.
Dysbiosis: symptoms and diseases
(gastrointestinal) symptoms often accompany dysbiosis:
- Stomach ache
- Chronic halitosis (susceptibility to halitosis) and susceptibility to infections due to reduced barrier function of the intestinal wall (damaged/permeable intestinal mucosa or intestinal leaks – in the German permeable intestine) are associated with dysbiosis.
Dysbiosis is currently associated with over 25 diseases or syndromes. You can find references in the literature on:
- Chronic Inflammatory Bowel Disease (IBD):
- Crohn’s disease
- Ulcerative colitis
- Irritable Bowel Syndrome (IBS)
- Recurrent Clostridium Difficile Infection (CDI)
- Colorectal cancer
- Allergy/atopy (type of hypersensitivity)
- Celiac disease (gluten intolerance)
- Diabetes type 1 and type 2
Probiotics are transient symbionts that remain briefly in the GI tract (several weeks). During this time, they can positively affect the intestinal microbiota. Therapeutic effects are achieved through three mechanisms:
Modulation of microbiota content in intestines
Maintaining the integrity of the intestinal barrier and preventing bacterial translocation (change of location)
Modulation of the local immune response by the gut-related immune system
Probiotic organisms interact with the immune system at many levels, including cytokine production, mononuclear cell proliferation, phagocytosis and macrophage killing, modulation of autoimmunity, and immunity to bacterial, protozoal pathogens. The effects of probiotics are most rain-specificity. This means that each strain has its own health benefits.
Prebiotics are indigestible substances that help maintain health by selectively stimulating benign bacteria’s growth in the intestines. Effective prebiotics reaches the colon and serves as food for a limited group of microorganisms with clearly identified health-promoting properties. The food components that best meet these criteria are present in oligosaccharides, sugar molecules that consist of several monosaccharides (simple sugars). These include inulins and their derivatives, fructooligosaccharides. These low molecular weight carbohydrates are naturally found in artichokes , onion, chicory, garlic, leek, and to a lesser extent in cereals. Other oligosaccharides like raffinose and stachyose are the main carbohydrates in beans and peas. Taking prebiotics can modulate the intestinal microbiota by increasing the specific microbiota’ composition. They have been shown to stimulate the growth of endogenous bifidobacteria, which are predominant in human feces after a short feeding period also on, this prebiotics modulate fat metabolism, most likely through fermentation produc.ts
Clinical use of probiotics should focus on matching the probiotic strain with useful clinical conditions. For probiotics and prebiotics to be effective, they must be resistant to stomach acid and bile to reach the intestinal tract where they can grow or fulfill their nutritional function. Dietary supplements with probiotics should therefore be coated with enteric acid. Not every bacterial strain of probiotics has colonized the gut. However, there may be health-promoting effects. For example, researchers found that certain probiotics did not change the gut’s overall bacterial composition but caused significant changes in the production of enzymes that are most involved in carbohydrate metabolism. Since these changes are related to these probiotics’ consumption and are therefore temporary, continuous use is necessary for a long-term effect.
Dosage and safety
Successful therapeutic doses in clinical trials varied between 107-1012 CFU * / day. In some open-label studies, as much as 3.6 trillion CFUs were administered daily. In children between 6 and 36 months of age, doses of 107-1010 CFU / day were successful. These are relatively small amounts if you consider that 1 milliliter in the colon contains 1010-1012 CFU, and the best results are achieved in the highest doses. These doses did not lead to side effects or complications and were found to be safe (in children, as much as 2 trillion CFU per day was given without problems). One colony-forming unit (CFU or CFU) is one size that plays a role in the quantification of microorganisms when growing several viable microorganisms in a material. For most populations, probiotic consumption is considered safe, and complications are rare. Probiotics, therefore, have the predicate “Generally recognized as safe” (GRAS or “generally recognized as safe” in German) and are also safe for vulnerable groups such as children, pregnant women, and the elderly. Side effects are harmless and temporary and are limited to bloating.
Probiotics have shown therapeutic effects on:
Diarrhea associated with Clostridium difficile
Infectious diarrhea with acute onset
Gastric or duodenal ulcer
Irritable bowel syndrome
Inflammatory bowel disease
Type 2 diabetes and metabolic syndrome
Upper respiratory tract infections
Urogenital infections in women