Probiotic bacteria are live microorganisms that, when consumed in adequate amounts, have a beneficial effect on our health. There are many probiotic strains, but the most commonly encountered belong to the genera Lactobacillus and Bifidobacterium. Their action is based on colonizing the intestines and supporting the natural gut microbiota, which leads to a range of positive health effects.

Today, probiotics are used in many different ways. Most often, they are taken to support digestion, improve intestinal comfort, restore the microbiota after antibiotic therapy, or during periods of reduced immunity. Increasingly, attention is also being given to their role in regulating immune system function, influencing overall well-being, and protecting the intestinal barrier. However, as probiotics become more popular, an important question arises: how exactly do they differ from one another, and how should they be categorized? To understand this, it is helpful to look at the basic classification of probiotic bacteria.

How can probiotic bacteria be classified?

Genus is the first level of classification and refers to a broad category of probiotic bacteria. Species is a more precise term that identifies closely related groups of bacteria within a genus. A strain, however, is the most specific unit, indicating particular populations of bacteria that differ genetically and functionally.

It is the strain that determines a probiotic’s ability to produce specific enzymes, synthesize bioactive compounds, and compete with other microorganisms in the gut. For this reason, choosing the right probiotic requires consideration of all three elements, with particular emphasis on the strain in order to fully benefit from its health-promoting properties.

What probiotic strains can we distinguish?

Lactobacillus acidophilus is one of the best-known probiotic strains. It helps maintain appropriate conditions in the intestines, limiting the growth of harmful bacteria and yeasts. It supports lactose digestion and may therefore be helpful for individuals who poorly tolerate dairy products. In addition, it strengthens the intestinal barrier and supports immune system function, which may help the body cope more effectively with infections and inflammatory processes.

Bifidobacterium bifidum is a strain that colonizes the human gut very early, already in the first days of life. In adults, it supports proper digestion, particularly in the large intestine. It participates in the breakdown of food residues and the production of substances that nourish intestinal cells. In this way, it helps maintain good intestinal condition and barrier integrity. It is also often associated with improved digestive comfort, especially in cases of bloating and irregular bowel movements.

Lactobacillus casei is a strain that performs well in the challenging conditions of the digestive tract, such as the acidic environment of the stomach. This allows it to effectively reach the intestines and exert its effects there. It helps maintain microbiota balance and supports the body’s natural defense mechanisms. It is often used after antibiotic therapy and during periods of weakness or increased stress, when the gut may be more susceptible to imbalance.

Lactobacillus rhamnosus is a strain that adheres well to the intestinal wall, enabling it to effectively compete with undesirable microorganisms. It supports immune system function and helps maintain microbiota balance. It is frequently used during and after antibiotic therapy and to help prevent diarrhea. For this reason, it is one of the more commonly used strains in probiotic preparations.

Why do different probiotics work differently?

The differences between probiotic strains primarily result from their biological properties and the way they interact with the body. Individual strains may colonize different sections of the digestive tract, vary in resistance to gastric acid, and differ in their ability to adhere to the intestinal epithelium. Some strains have a stronger effect on digestion, others on immunity or on protecting the intestinal barrier. These differences explain why probiotics do not work identically and why their effectiveness depends on the specific strain and the needs of the body.

This is also evident when comparing the four strains described above. Each supports the body in a slightly different way. Lactobacillus acidophilus acts mainly in the small intestine and is particularly useful in cases of lactose digestion issues and for maintaining microbiological balance. Bifidobacterium bifidum focuses primarily on the large intestine and is associated with digestive comfort, regular bowel movements, and nourishment of intestinal cells. Lactobacillus casei stands out for its high resistance to digestive tract conditions, making it suitable during periods of physical weakness and after antibiotic therapy. Lactobacillus rhamnosus strongly binds to the intestinal wall and effectively limits the proliferation of undesirable microorganisms, supporting immunity and helping to prevent diarrhea. In practice, this means that different strains complement one another, and their combination may provide broader support for gut health.

In addition to the most frequently discussed strains, others are also commonly included in probiotic formulations and complement their effects. Lactobacillus paracasei, Lactobacillus plantarum, and Lactobacillus reuteri are often associated with supporting immunity and intestinal balance. Lactobacillus paracasei helps the body respond more effectively to external factors and is sometimes used during periods of increased infection risk. Lactobacillus plantarum is known for good tolerance in the gut and its ability to support digestion, including in individuals with sensitive digestive systems. Lactobacillus reuteri supports microbiological balance and is also recognized for its positive effect on intestinal comfort and overall digestive health.

It is also worth mentioning strains from the genus Bifidobacterium, which primarily act in the large intestine. Bifidobacterium animalis and Bifidobacterium breve belong to this group. Bifidobacterium animalis supports regular bowel movements and helps maintain a proper intestinal rhythm. Bifidobacterium breve is particularly important for microbiota balance and is often associated with improved digestive comfort and immune support, especially in children but also in adults.

Summary

In summary, different probiotics work differently because they contain different bacterial strains, and each strain plays a slightly different role in the body. Some support digestion, others immunity, and still others help maintain microbiota balance. Therefore, when choosing a probiotic, it is worth paying attention to the composition and specific strains rather than focusing only on the product name. It is the strains that determine what type of support the body actually receives.