How does the immune system work? Learn to understand and influence it.

Das Immunsystem und sein internes Netwerk

The influence of our way of life and especially the diet has a decisive influence on our metabolic processes. This includes not only digestion such as the decomposition and absorption of nutrients, but also the many other processes that take place in our body every second. Every second, new blood cells are formed and old ones are recycled. We lose thousands of skin cells, which regenerate again. Muscle cells are repaired, hair and nails grow and much more.

How does the immune system work?

The body is in a constant balancing act between death and the creation of new cells, hormones, and tissues.

These metabolic processes also include all processes related to the immune system. Despite thousands of research projects and studies, not all the secrets of the complex interaction of the immune processes have been deciphered.

Our immune system requires a complex structure of immunocompetent systems to function, including:

  • the bone marrow
  • the thymus
  • the lymph nodes
  • the spleen
  • the skin
  • the intestine and the intestinal flora
  • specialized immune cells and messenger substances in the blood

The functions of the immune system

The immune system has very specific tasks in the body, including:

  • Maintaining natural barriers (skin, intestinal wall)
  • Screening for foreign bodies
  • initiate defensive reactions
  • Recognize and kill mutant cells
  • Manage immune memory

In order to master all these tasks, our immune system consists of two parts. The non-specific immune system and the specific immune system.

The non-specific immune system consists of natural barriers (skin, intestinal wall) and a network of defense cells that attack or prevent everything that is foreign and can be assigned to a certain pattern, respectively, from entering the body.

The specific immune system consists of adaptable and adaptive cells. It is controlled by the thymus, which uses the scavenger cells to initiate an immune-specific response to an invasion of harmful foreign bodies. This happens when influenza viruses attack, here the body produces new immune bodies that specifically neutralize these influenza viruses. However, this process can take a few days. Even after the flu, these cells remain in the body, creating a kind of memory effect that can last from weeks to a few years. If the same foreign body is infested again, the immune system can now react at lightning speed.

It is important that the immune system is always in balance, an excessive or insufficient immune reaction is not desirable.

diseases of the immune system

Our immune system itself can also have malfunctions and disorders, it is then itself ill or out of balance. Many factors can have a positive or negative effect on the immune system:

  • Lifestyle (stress, little sleep, lack of exercise, elite sports)
  • Medication (antibiotics, painkillers, vaccinations, hormone therapies)
  • Infections (bacteria, viruses, fungi)
  • Environmental toxins (heavy metals, pesticides, chemical substances)
  • Nutrition (overnutrition, undernutrition, malnutrition)
  • stimulants (drugs, alcohol, tobacco)
  • Additives (emulsifiers, flavorings, colorings)
  • physical stress (electrosmog, radiation)

The studies on the influence of environmental factors and excessive hygiene are not yet clear. What is certain, however, is that these also affect the immune system. In the case of allergies, the immune system reacts to daily foreign bodies like the pollen in hay fever. In autoimmune diseases, the immune system mistakenly attacks its own body cells. 

How do I strengthen my immune system

The immune system can only function optimally if it is supplied with the necessary nutrients and building blocks. The key to this is a wholesome and balanced healthy diet. But rest and relaxation are also crucial.

"Sleep affects various immune parameters, is associated with a reduced infection risk, and can improve infection outcome and vaccination responses." The Sleep-Immune Crosstalk in Health and Disease. 2019 Jul 1;99(3):1325-1380

Important factors when choosing foods are that they should be as natural as possible. Fresh fruit and vegetables are rich in vitamins, minerals and secondary plant substances.

Fresh, high-quality oils and a balanced amino acid balance also support the immune system and are important for optimal functioning.

The Greek scholar recognized more than 2000 years ago how important a healthy diet is for the body and the immune system Hippocrates.

"Let food be thy medicine and medicine be thy food", Hippokrates 460 v. Chr. 

Hippocrates was of the opinion: "Health can only be maintained through a correct mixture of bodily fluids, which of course depend very much on nutrition and a natural way of life. An incorrect mixture of bodily fluids disturbs the harmony of life and thus the balance in the body."

hygiene and the immune system

Hygiene is particularly important for the aforementioned non-specific immune system. Balanced personal hygiene can support the natural barrier, our skin, and thus reduce the penetration of malicious foreign bodies.

Hygiene in the intimate area is particularly important, because there, in addition to the mouth, ears and nose, there are other entrance gates into our body.

A healthy level of hygiene is also important, so excessive hygiene can also deprive the immune system of its ability to adapt to new situations and pathogens. In addition, excessive showering (several times a day) can destroy the skin's natural protective barrier.

Immune system supporting nutrition

As already mentioned in the previous chapter, a healthy and balanced diet is essential to optimally support the immune system. But what is a healthy diet?

Here are 8 simple rules to keep in mind:

  1. Eat 4-6 servings of fresh fruit and vegetables daily.
  2. Make sure you get enough fiber (min 30g/day).
  3. Prefer complex carbohydrates from whole grain and starchy foods (potatoes, rice).
  4. Don't eat more calories than you need on a daily basis.
  5. Prepare your food nutrient-friendly (do not overcook).
  6. Use health-promoting fats (omega-3 and omega-6).
  7. Use animal foods for nutritional supplements.
  8. Drink enough water.

Frau reicht mir einen Apfel

Influence of sport on the immune system

In addition to a healthy and balanced diet, our physical activity also plays an essential role in optimally supporting the immune system. Sport promotes important hormones and metabolic processes and helps the body to remain vital. Outdoor exercise has a positive effect on our oxygen supply and vitamin D levels. Vitamin counts as one of the immune-relevant vitamins. 

Study results show favorable effects of moderate endurance training on the functionality of the immune system. 

With moderate physical activity, training studies have shown an improvement in the activity of the immune system.

Immunosenescence is defined as an immune dysregulation associated with the aging process. Recent data show that habitual exercise can improve immune system regulation and delay the onset of immunosenescence.

However, repetitive, heavy training sessions, such as those often found in elite athletes, have a negative effect on the immune system. Persistent heavy loads can promote infections and inflammatory processes.

Athleting macht Posing beim Sport mit Beyond Nutrition T Shirt

The role of the intestinal flora

The so-called microbiome, also known as the intestinal flora, plays an important role in the immune system. Our gut is home to billions of bacteria that interact with our bodies in unique ways. A high-fiber diet helps to support the intestinal flora and above all the healthy bacteria.

The influence of the intestinal flora on our general well-being is currently being intensively researched. It's a lot bigger than many expected.

They ensure a functioning and foreign body-repellent intestinal wall. By optimizing the absorption of nutrients through the intestinal wall and neutralizing harmful bacteria, the intestinal flora plays a crucial role as part of the immune system.

The role of micronutrients

The right supply of micronutrients, including above all vitamins, trace elements and secondary plant substances, are essential for a healthy immune system. Here, in turn, the aspect of a healthy diet and lifestyle plays a decisive role.

The right balance of micronutrients is an important factor

That Vitamins, trace elements and secondary plant substances support the immune system has already been proven by a number of studies. However, you should try to pay attention to the right balance because vitamins, trace elements and secondary plant substances also interact with each other and thus influence our metabolic processes.

The following nutrients have an immune-relevant effect:

minerals and trace elements Vitamins essential fatty acids amino acids 
Zink Pro-Vitamin A Omega 3 fatty acids essential amino acids
Selenium Vitamin A Omega 9 fatty acids arginine
Iodine Folic Acid (B9) Ornithin
copper Vitamin C Cysteine
To demand Vitamin D Glutamine
molybdenum Vitamin E

Secondary plant substances and the immune system, new basics

The wrongly named "secondary" plant substances are increasingly coming into focus. These are substances that the plant needs to protect itself against enemies or serve as a dye. However, it is precisely these substances that play a decisive role in our health because they influence a large number of metabolic processes.

They are mainly found in fruit, vegetables, nuts and legumes.

The level of knowledge about secondary plant substances has changed significantly in recent years. More and more studies on the mode of action of these plant substances are published every year. 

The new findings in metabolomics support the value of fresh fruit polyphenols as potential countermeasures to training-induced immune changes (proven by 4 studies).

They probably have a preventive effect on various types of cancer and mediate vascular effects such as dilation of blood vessels and lowering of blood pressure. Secondary plant substances also develop neurological, anti-inflammatory and antibacterial effects.

Errors, what is true and what is not

Vitamins and minerals have a positive effect on the duration of infection. - CONDITIONAL

In general, this statement is not supported by studies. There are some exceptions such as vitamin C, zinc and selenium where supplementation can reduce the duration of infection. A correct dosage and intake must take place here. Other nutrients may also have an impact.

High doses of vitamins and minerals make me more resistant to infections. - INCORRECT

No, prolonged intake of high doses Vitamins and minerals can often do more harm than good. There are preventive therapies, but these must be discussed with a specialist.

Taking supplements is necessary to ensure an optimal supply of micronutrients for the immune system. - INCORRECT

Taking supplements is generally not necessary for healthy people who pay attention to a healthy diet and lifestyle. The use of supplements should be tailored to individual needs. Exceptions are vitamin D and people who live according to a special diet resp. Conditions exist that affect the absorption of nutrients.

Vitamins and minerals support my immune system. - CORRECT

It has been scientifically proven that certain Vitamins, minerals and trace elements support the immune system in a healthy and optimal functioning. However, optimization beyond the natural optimal (or normal) state is not possible.


Part of further training to become a fitness and sports nutrition consultant 

Sport and the immune system -

Glutamine and the immune system

Burgenstein handbook nutrients, 13th edition (ISBN:978-3-432-10657-1)

Effects of Acute and Chronic Exercise on Immunological Parameters

German Society for Nutrition

The compelling link between physical activity and the body's defense system