How the gut supports immunity

The immune system is one of the most complex systems in the human body. Every day it protects us from bacteria, viruses, and other microorganisms that can cause disease. Contrary to common belief, immunity is not simply an abstract “strength of the body.” It is an extensive network of cells, tissues, and biological mechanisms that work together to recognize threats and effectively neutralize them.

What is immunity?

Immunity can be defined as the body’s ability to recognize and fight pathogens, which are microorganisms capable of causing disease. The immune system not only responds to threats but can also remember previous infections, allowing it to react faster and more efficiently in the future.

In biology, two main types of immunity are distinguished: innate immunity and acquired immunity.

Innate immunity, also called non specific immunity, is the defense system we are born with. It acts immediately after contact with a foreign microorganism and involves general protective mechanisms of the body. These include physical barriers such as the skin and mucous membranes, as well as immune cells capable of rapidly destroying pathogens. The response of this part of the immune system is fast, but it is not directed against a specific microorganism. For this reason, it can sometimes be less precise.

The second mechanism is acquired immunity, also known as adaptive or specific immunity. It develops during life when immune cells encounter a particular antigen, a molecule characteristic of a specific pathogen. When the body meets a microorganism for the first time, the immune response is relatively slow. The body is still learning to recognize the threat and preparing the appropriate defensive reaction. This is why the first encounter with a virus or bacterium often leads to an infection.

During this process, however, immunological memory is created. This means that when the body encounters the same pathogen again, the immune system reacts much faster and more effectively. This mechanism forms the foundation of vaccination and the natural development of immunity throughout life.

Why do children get sick more often than adults?

Frequent infections in children are a natural part of the development of the immune system. A child’s body is still becoming familiar with the wide range of microorganisms present in the environment, and the immune system is building the experience needed for effective defense.

In a way, infections serve as biological training for the immune system. Each encounter with a new pathogen activates a process of learning and building immunological memory. This is why children, especially those in preschool and early school years, tend to experience infections more often than adults.

The immune system reaches full maturity only around the age of twelve. Until then, the body gradually develops the ability to recognize pathogens quickly and respond to them effectively.

How the gut supports immunity

In recent years, scientists have paid increasing attention to the role of the gut in immune system function. The digestive tract is not only responsible for processing food. Within the intestinal walls there is a complex network of lymphoid tissue known as GALT, or gut associated lymphoid tissue.

This part of the immune system is directly linked to the intestinal mucosa. It is estimated that around 70 to 80 percent of the cells responsible for producing immunoglobulins, antibodies that recognize and neutralize pathogens, are located in this area.

When microorganisms enter the digestive tract, immune cells present in the intestinal wall begin producing antibodies that protect the body. However, this process functions properly only when the intestinal environment remains healthy.

A major role here is played by the gut microbiota, the community of microorganisms living in the intestines. These bacteria participate in many biological processes, ranging from the metabolism of nutrients to the regulation of immune responses.

Diet and the health of the microbiota

The condition of the gut microbiota largely depends on everyday diet. One of the most important elements supporting its balance is dietary fiber, which is found mainly in vegetables, fruits, and whole grain products.

Unlike many other nutrients, fiber is not digested by enzymes in the human digestive system. Instead, it becomes food for gut bacteria. This allows microorganisms to grow and form stable, diverse communities.

Foods rich in fiber include berries, dried plums, beans, broccoli, and grain products such as groats, brown rice, whole grain bread, and oats.

Polyphenols found in many plants also support the microbiota. These compounds are present in berries, nuts, soy, and green tea. They promote microbial diversity and help maintain balance in the intestinal environment.

Fermented foods and lactic acid bacteria

Fermented foods are another important element of a diet that supports the microbiota. This group includes products such as fermented vegetables, yogurt, kefir, and kombucha. They contain lactic acid bacteria that may enrich the gut microbiota.

Although not all fermented foods meet the strict scientific definition of probiotics, regular consumption of these products can positively influence the intestinal environment. It is important, however, to pay attention to the composition of these foods. The best yogurts and kefirs usually contain only milk and live bacterial cultures or kefir yeasts.

Another interesting option is preparing yogurt at home. This can be done using special bacterial cultures such as the Narine strain, Lactobacillus acidophilus Er 317/402. This bacterium belongs to the group of lactic acid bacteria and is sometimes used as a starter culture for milk fermentation.

The role of probiotics

In addition to fermented foods, the microbiota can also be supported through probiotic supplementation. Probiotic preparations contain specific strains of microorganisms intended to temporarily support the microbiological balance of the intestines.

When choosing a probiotic, several aspects are worth considering. The packaging should contain the full name of the bacterium, including the genus, species, and strain designation. An example is Lactobacillus acidophilus Er 317/402.

Another important factor is the number of bacteria contained in a single dose. In many cases, capsules or sachets should contain at least several billion colony forming units, abbreviated as CFU.

The shelf life of the product is also important. Probiotic bacteria are living microorganisms, and their numbers gradually decrease during storage. The fresher the product, the greater the likelihood that the bacteria it contains remain active.

Lifestyle and immunity

Immunity depends not only on diet or gut microbiota but also on daily lifestyle habits, including sleep, stress levels, and physical activity.

Sleep plays a major role in the body’s regenerative processes. During sleep, the immune system rebuilds its resources and prepares for new challenges. Lack of sleep may weaken the body’s defense mechanisms. Preschool children usually need about 12 to 14 hours of sleep per day, school aged children around 9 to 11 hours, while adults need about 8 hours on average.

Stress is another factor that influences immunity. Long term psychological stress can increase inflammatory processes in the body and disturb the balance of the gut microbiota. Many people experience respiratory infections or recurrent cold sores after particularly stressful periods of life, which is often a consequence of temporarily weakened immunity.

Physical activity should also not be overlooked. Moderate exercise supports the proper functioning of the immune system. During physical activity, the number and activity of macrophages increase. These immune cells are responsible for absorbing and destroying microorganisms. Regular walks, cycling, or exercising outdoors can therefore support the body’s natural defense mechanisms.

Summary

Immunity is the result of cooperation between many biological systems. The immune system itself, the gut microbiota, diet, and lifestyle all play an important role.

The intestines are one of the most important areas involved in immune system activity, as a large portion of antibodies that protect the body from pathogens are produced there. For this reason, supporting gut health through a varied diet, adequate fiber intake, fermented foods, and balanced lifestyle habits can significantly strengthen the body’s natural defense mechanisms.