The Mechanism of Action of Probiotics: A Scientific Perspective

Probiotics are live microorganisms that have a positive effect on human health when consumed in adequate amounts. In recent years, interest in probiotics has grown as the impact of gut health on overall health has become better understood. However, how exactly do probiotics work in the body? In this article, we will examine the mechanisms of action of probiotics in detail, based on scientific research conducted over the past decade.

General Definition and Types of Probiotics

The World Health Organization (WHO) defines probiotics as “live microorganisms that, when consumed in adequate amounts, confer a health benefit on the host” [1]. Probiotic microorganisms typically include species such as Lactobacillus, Bifidobacterium, and Saccharomyces boulardii. Recent studies have shown that these microorganisms exert beneficial effects on health through various mechanisms, including colonization in the gut, modulation of the immune system, and inhibition of pathogens [2].

Primary Mechanisms of Action of Probiotics

The positive effects of probiotics on health can be explained by various mechanisms. Based on scientific studies conducted over the past decade, the following mechanisms are primarily highlighted:

1. Modulation of the Gut Microbiota

The most fundamental mechanism of action of probiotics is to regulate the gut microbiota and restore the balance of the gut flora. Probiotics can prevent the colonization of pathogenic bacteria by adhering to the intestinal wall, support the proliferation of beneficial bacterial species, and thus increase the diversity of the gut microbiome [3]. Studies have demonstrated that Lactobacillus and Bifidobacterium species support gut health by inhibiting the growth of pathogens in the gut flora [4].

2. Inhibition of Pathogen Growth and Adhesion

Probiotics exhibit protective effects by inhibiting the adhesion and growth of harmful microorganisms in the gut. This mechanism occurs through probiotic bacteria strongly adhering to the intestinal mucosa and occupying the colonization sites of pathogens. Additionally, antimicrobial substances such as lactic acid, hydrogen peroxide, and bacteriocins produced by probiotics suppress the growth of pathogens [5].

3. Modulation of the Immune System

The positive effects of probiotics on the immune system have been strongly supported by recent studies. Probiotic bacteria can regulate the immune response by interacting with immune cells in the intestinal mucosa. Research has shown that probiotics can modulate the function of immune cells such as dendritic cells, macrophages, and lymphocytes, thereby altering cytokine production and reducing inflammation [6]. Certain specific probiotic strains, such as Lactobacillus rhamnosus GG, have been clinically shown to enhance the immune system [7].

4. Enhancement of Gut Barrier Function

The protection and strengthening of the intestinal epithelial barrier is an important mechanism of action for probiotics. Probiotic bacteria interact with intestinal epithelial cells to increase mucus production, strengthen tight junction proteins in epithelial cells, and reduce intestinal permeability. This makes the intestinal barrier more resistant to pathogens and harmful substances [8]. For example, clinical studies have supported that the Bifidobacterium infantis strain enhances intestinal barrier function and reduces intestinal permeability [9].

5. Communication Between the Nervous System and the Intestine (Gut-Brain Axis)

In recent years, scientific research on the effects of probiotics on the gut-brain axis has gained importance. Probiotics can stimulate the production of neurotransmitters (such as serotonin and GABA) in the intestines and influence central nervous system functions through these molecules. Clinical studies have demonstrated that probiotics can have positive effects on psychological conditions such as anxiety, depression, and stress [10].

Conclusion and Evaluation

Over the past decade, scientific research has revealed that probiotics have multifaceted and complex mechanisms of action on human health. Probiotics can exert beneficial effects on health by regulating the gut flora, strengthening the gut barrier, inhibiting the growth of pathogens, modulating the immune system, and exerting effects on the central nervous system through the gut-brain axis. These potential benefits of probiotics make them a promising option for the prevention and treatment of various health issues.

However, the efficacy and benefits of probiotics may vary depending on the species, dosage, and intended use. Therefore, the mindful use of probiotic supplements and the selection of specific strains supported by clinical research are important.

Disclaimer: The information provided in this blog is for informational purposes only and does not constitute medical advice. Consult a healthcare professional before making any changes to your diet, lifestyle, or health regimen.

References

[1] Hill C et al. Nat Rev Gastroenterol Hepatol. 2014;11(8):506-514.

[2] Sanders ME et al. Gut Microbes. 2019;10(2):204-217.

[3] Hemarajata P, Versalovic J. Ther Adv Gastroenterol. 2013;6(1):39-51.

[4] Plaza-Diaz J et al. Nutrients. 2019;11(1): 192.

[5] Bermudez-Brito M et al. Annals of Nutrition and Metabolism. 2012;61(2):160-174.

[6] La Fata G et al. Frontiers in Microbiology. 2018;9:2756.

[7] Maldonado Galdeano C et al. Frontiers in Immunology. 2019;10:129.

[8] Hiippala K et al. Nutrients. 2018;10(8):988.

[9] Chichlowski M et al. Benef Microbes. 2012;3(4):295-307.

[10] Cryan JF et al. Physiol Rev. 2019;99(4):1877-2013.