Probiotics: A short, scientific guide!

The human body hosts a variety of microorganisms, which are not only not harmful, but also offer several benefits to our health and well-being (probiotics). Most of these microorganisms are bacteria and most of them are found in the gut. Bacteria coexist with the cells of the human body and are in a delicate balance with them. Only if this balance is disturbed, these bacteria can become pathogenic (1).

The appropriate strains of gut bacteria and the appropriate number of them have been associated with various beneficial effects on the body (2,3), such as:

• Weight loss
• Improved digestion
• Improved immune system function
• Healthier skin
• Reduced chance of developing specific diseases

 

But what are probiotics?

The term "probiotics" - according to the World Health Organization - refers to microorganisms, the intake of which in appropriate quantities, through food or dietary supplements, provides many benefits to the host (4). The term “probiotics” usually refers to live bacterial strains, as well as to some fungi, which also have beneficial properties for the body.

As mentioned before, probiotics can be obtained either through food or through specialized dietary supplements. The foods that are suitable for probiotic intake are those that result from bacterial fermentation, ie yogurt, kefir, sauerkraut, soft matured cheeses, wine, beer, etc.

Along with probiotics, we should also talk about prebiotics, which are carbohydrates, usually dietary fiber, which are the food of probiotics.

Products that contain both probiotics and prebiotics are called symbiotics. A product, which contains the appropriate bacterial strains, in the appropriate quantities, but also their food - prebiotics -, is considered a symbiotic (6).

The most common probiotics used in dietary supplements are Lactobacilli and Bifidobacteria. Saccharomyces, Streptococcus Enterococcus, Escherichia, and Bacillus are also used. Each genus has different species, and each species has different strains. Dietary supplement labels will show the strain (which also contains the genus in its name), for example Lactobacillus rhamnosus GG7.

 

The importance of probiotics for gut health.

The diverse community of microorganisms in the gut is the gut flora. It is also called gut microbiome (8). Most of the gut bacteria is located in the large intestine and colon, as they form the largest part of the gastrointestinal tract. The gut microbiome produces vitamins, including vitamin K and some B-complex vitamins. Another function is to convert fiber into short-chain fatty acids (SCFAs), such as butyric-, propionic-, acetic acid, which are involved in many metabolic processes (9).

The abovementioned fatty acids stimulate the immune system and strengthen the intestinal epithelial barrier. This helps prevent the entry of pathogenic microorganisms (10).

The gut microbiome is extensively linked to the quality of our diet and an unbalanced gut microbiome has been found to be associated with the development of various diseases (11), such as obesity, type 2 diabetes, metabolic syndromes, heart disease, bowel cancer, Alzheimer’s, and depression (12, 13,14,15). Pro- and prebiotics help to restore the balance of the gut microbiome.

 

Probiotics promote the health of the gastrointestinal tract.

Probiotics are generally related to the proper functioning of our gastrointestinal tract. Studies have shown that dietary supplements with probiotics can help treat antibiotic-related diarrhea (16). Diarrhea is a very common side effect in patients receiving antibiotic therapy and may occur even after treatment. This is because antibiotics do not target specifically the pathogens, they also eliminate the beneficial bacteria for the body. This upsets the balance of the gut flora and gives way to pathogenic bacteria to grow.

Probiotics have also been linked to the treatment of Irritable Bowel Syndrome (IBS) as long-term use of probiotics has been found to reduce flatulence, bloating, constipation and diarrhea among other symptoms (17).

Maintaining a healthy and balanced microbiome is multifaceted and can be enhanced in a variety of ways, such as nutrition and exercise. However, dietary supplements with probiotics offer many benefits in protecting and maintaining the gastrointestinal well-being.

 

Bibliography:

1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4425030/
2. https://www.mdpi.com/2072-6643/11/7/1613/htm#B70-nutrients-11-01613
3. http://www.tlsr.usm.my/tlsr27022016/27022016_06.pdf
4. https://www.nature.com/articles/nrgastro.2014.66
5. https://www.mdpi.com/2076-2607/8/4/483
6. https://www.nature.com/articles/s41575-020-0344-2?utm_medium=affiliate&utm_source=commission_junction&utm_campaign=3_nsn6445_deeplink_PID100090071&utm_content=deeplink
7. https://www.worldgastroenterology.org/UserFiles/file/guidelines/probiotics-and-prebiotics-english-2017.pdf
8. https://www.bmj.com/content/361/bmj.k2179
9. https://pubmed.ncbi.nlm.nih.gov/25273884/
10. https://pubmed.ncbi.nlm.nih.gov/25481240/
11. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4566439/
12. https://www.frontiersin.org/articles/10.3389/fmicb.2018.01835/full
13. https://www.clinicsandpractice.org/index.php/cp/article/view/987/834
14. https://pubmed.ncbi.nlm.nih.gov/24495527/
15. https://www.frontiersin.org/articles/10.3389/fcimb.2020.00104/full
16. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5745464/
17. https://badgut.org/information-centre/a-z-digestive-topics/probiotics-for-irritable-bowel-syndrome/