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Preventing Colds: Strengthening the Immune System with Micronutrients

The wintery season is the time when more and more common colds occur. The so-called banal respiratory infections are the most common diseases in industrialized countries. They account for about 40% of all working-age absenteeism and are also the leading cause of absenteeism among students.

Colds are based on viral infection in 97% of cases and are self-limiting, i.e. they heal, even without medical measures. In viral infections, antibiotics are not effective, so there is no need for antibiotic therapy in colds except for few cases.

Colds are often referred to as flu, but this is rarely justified. The flu is not a banal virus infection, but a serious disease caused by influenza viruses. The most common causes of respiratory infections are not the influenza viruses, but rhinoviruses, corona viruses and respiratory syncytial viruses.

The term “colds” clearly suggests that these diseases are related to cold, i.e. the exposure to cold is considered to be a major factor in triggering the ailment. The extent to which cold is actually a causative factor, however, is scientifically highly controversial. In most studies it could not be proven that cold actually increases the risk of infection. However, cold leads to a reflex narrowing of the blood vessels in the upper respiratory tract. This decrease in blood flow could result in less immunocompetent cells being transported.

Crucial to the risk of infectiousness is the fact that in the winter months, one comes into contact with pathogens more often. In autumn and winter, the viruses survive longer without a host. In addition, in winter we spend more time in closed rooms and there is an increased dehydration of the mucous membranes of the nose and throat increasing the risk of infection. Of course, the functioning of the immune system plays a central role in the risk of infection. The immune system consists of diverse complex structures and is distributed throughout the body like a network. So it is not an organ, such as the liver or the heart. The immune system includes the bone marrow, the thymus, the lymph nodes, the spleen, the intestinal mucosa and the skin. The immune system consists of a large number of specialized immune cells as well as several immune messenger substances and immunoglobulins.

The functioning of the immune system can be impaired by various factors, which may increase the susceptibility to infection or favor other malfunctioning of the immune system such as allergies or autoimmune diseases.

The immune system is weakened by

  • mental stress, e.g. agitation, persistent psychosocial and / or intrapsychic stress
  • lack of sleep
  • wrong eating habits, e.g. too high calorie intake, malnutrition
  • medications, e.g. painkillers, cortisone
  • environmental pollutants and home poisons
  • luxury foods

The immune system must be flexible and fast to meet new challenges and is therefore always dependent on an adequate availability of nutrients. Already the lack of one micronutrient can sensitively disturb the immune competence. The immune system, like all other organ, is subject to an aging process. The number and biological activity of the immune cells is thus somewhat declining. The inflammatory activity of the organism increases. Overall, there is an increased susceptibility to infectious diseases. This can be prevented or at least mitigated by a good micronutrient supply.

Amino Acids

Arginine is the starting substance for the formation of the signal gas nitrogen monoxide (NO). Macrophages produce large amounts of NO to kill off bacteria and cells. In addition, arginine activates the natural killer cells.

Cysteine ​​is a sulfur-containing amino acid and an important source for the synthesis of glutathione. Glutathione is a tripeptide consisting of cysteine, glycine and glutamic acid. It is an important intracellular antioxidant and a regulator of the cell metabolism. Glutathione increases lymphocyte proliferation. A glutathione deficiency leads to a limitation of immune functions. Cysteine ​​is often supplemented in the form of N-acetylcysteine. NAC is marketed as a mucus remover; the effect profile of the substance, however, is much more comprehensive. In a study the supplementation with NAC significantly reduced the incidence and severity of influenza symptoms. NAC has an antioxidant and anti-inflammatory effect.

Glutamine is an essential nutrient substrate for rapidly dividing cells, including immune cells. Glutamine increases the activity of lymphocytes and is also important for stabilizing the mucosal barrier in the intestine and bronchi. A glutamine deficiency prevents the rapid formation of new immune cells. Infections, inflammations or otherwise severe physical and / or mental stress reduce the organism’s glutamine pool.

Glycine is part of the glutathione molecule and has pronounced anti-inflammatory properties.

Lysine is important for the prevention and treatment of cold sores. These are triggered by the herpes simplex virus type 1. Lysine can also be taken preventively – but at the same time the arginine intake should be limited. Arginine plays a significant role in the growth of herpes viruses.

Taurine is a sulfur-containing amino acid with numerous metabolic functions. Neutrophil granulocytes contain relatively much taurine. This is needed to limit the immune reactions that release many free radicals. Taurine also prevents the formation of proinflammatory cytokines.


Vitamin A is important for the integrity of the skin and mucous membranes. Healthy mucous membranes are important as a barrier against pathogens.
Vitamin A is indispensable for the growth of B-lymphocytes and therefore also for the formation of antibodies. Supplementation of vitamin A also increases the number of T-lymphocytes and the activity of natural killer cells. Even a slight vitamin A deficiency increases the risk of infections by two to three times. Originally, vitamin A was called the anti-infective vitamin. Vitamin A not only has preventive properties, but is also important in already existing infections, since in infections there is a decrease in vitamin A concentration. This can be compensated by vitamin A supplementation. Several studies have shown that vitamin A has a protective effect against childhood pneumonia.

Vitamin D is a major regulatory molecule of the immune system. Vitamin D induces the differentiation of monocytes and macrophages and also influences their function. By controlling cytokine production in inflammatory reactions, vitamin D has an anti-inflammatory effect. In addition, vitamin D induces the formation of antimicrobial peptides and thereby enhances the action of macrophages. Vitamin D deficiency increases the risk of respiratory infections and autoimmune diseases. A vitamin D deficiency promotes the development of bronchiolitis in children. When susceptible to infection, the level of vitamin D should be determined, as the basis for a needs-based supplementation.

Vitamin E is an important fat-soluble antioxidant and is essential for the functioning of the immune system. Vitamin E is important for the maintenance of the immune competence in the elderly person. With increasing age, the functioning of the immune system is reduced, which can be reversed by vitamin E supplementation. Vitamin E reduced the frequency of pneumonia in seniors.

Vitamin B1 has a central significance in the breakdown of carbohydrates and also possesses antioxidant properties. Oxidative stress due to a vitamin B1 deficiency can impair the function of immune cells. In general, a suboptimal vitamin B1 supply is relatively common, as the organism has only low vitamin B1 storage. Vitamin B1 is important for the mood as well as the physical and mental condition. Mental distress increases the susceptibility to infection.

Vitamin B2 produces important coenzymes of the energy metabolism. Vitamin B2 deficiency increases pro-inflammatory processes in the body. Vitamin B2 deficiencies are not rare. Especially in vegan nutrition care should be taken of an adequate vitamin B2 supply.

Vitamin B6 is central to the amino acid and protein metabolism. Low vitamin B6 status impairs immunocompetence, especially in elderly patients. The proliferation of lymphocytes is limited, as well as the formation of various messenger substances and antibodies. Overall, a vitamin B6 deficiency impairs the humoral as well as the cell-mediated immune response.

Vitamin B12 is required to convert folic acid into its active form. Folic acid is needed for DNA synthesis, i.e. the multiplication of immune cells depends on the folic acid supply. The supply of folic acid also has an influence on the formation of interleukin-2. The supply of vitamin B12 is often inadequate in the elderly, as there is an increased incidence of vitamin B12 uptake with increasing age. Taking proton pump inhibitors or Metformin may also worsen the vitamin B12 status. Basically, a vitamin B12 supplementation is mandatory for vegans.

Vitamin C is an important water-soluble antioxidant and is also essential for the functioning of the immune system. Vitamin C deficiency increases the risk of respiratory infections. In general, the vitamin C requirement of granulocytes is significantly increased in infections. Vitamin C supplementation in respiratory diseases can reduce the severity of the symptoms. Also in the treatment of pneumonia, especially in the elderly, vitamin C has a beneficial effect. For decades, it has been controversial to what extent the intake of vitamin C for colds makes sense. The current state of knowledge is: Vitamin C improves the severity and shortens the duration of cold symptoms. As a preventive measure, vitamin C is mainly effective in people who are exposed to increased physical stress.

Trace Elements

Selenium is an essential trace element and has an effect in the organism on various selenoproteins, e.g. glutathione peroxidases. Selenium is an important antioxidant and is also needed for the functioning of the immune system. Selenium deficiency increases the susceptibility to several types of viruses, including influenza viruses and increases the severity of flu symptoms. The selenium content of foodstuffs depends on the selenium content of the soil. This is low in Central Europe, so an insufficient selenium status is also very common. Especially in the autumn and winter months, therefore, the selenium level should be checked and selenium supplemented if necessary.

Iron is a trace element with very diverse properties. It is not only important for oxygen transport, but also for energy production, nerve metabolism, detoxification capacity of the liver, collagen synthesis, etc. An iron deficiency also affects immune functions. Iron is needed for DNA synthesis and thus for the proliferation of lymphocytes and for the respiratory burst. This refers to the formation and release of oxygen radicals by certain immune cells, which are necessary for the intracellular digestion of pathogens. In bacterial infections iron therapy should not be used as iron is a growth factor for bacteria. The iron storage protein ferritin is usually increased in infections and inflammations and in these cases is not a suitable marker for the assessment of the iron supply.

A copper deficiency leads to a reduction in the number of leucocytes (leukopenia). Copper deficiency also reduces the effectiveness of the respiratory burst. In addition, in the case of copper deficiency, the number of natural killer cells is reduced.

Zinc is part of more than 300 enzymes. Several functions of the immune system are zinc-dependent. In the case of a zinc deficiency, the number of lymphocytes and their activity are reduced. A zinc deficiency not only increases the susceptibility to infection, but also favors allergies and autoimmune diseases – a deficiency thus leads to a dysregulation of the whole immune system. Zinc supplementation inhibits the activity of herpes viruses and viruses causing a cold. For acute infections and colds, zinc supplementation, e.g. in the form of lozenges, may reduce the duration of a disease; but amounts over 75 mg per day are required. Zinc works best when taken within the first 24 hours of the onset of the first cold symptoms. Zinc also reduces the duration of severe pneumonia.

Other Micronutrients

Carnitine is a transport molecule for fatty acids in the mitochondria. It is therefore very important for the energy metabolism. Carnitine has immunomodulatory and anti-inflammatory properties. It increases the lymphocyte proliferation as well as the phagocytosis capacity of leukocytes.

Coenzyme Q10 is of central importance for energy metabolism. Immune cells have a high energy requirement. In addition, coenzyme Q10 is a lipophilic antioxidant that can regenerate oxidized glutathione as well as vitamin E.

Magnesium, as the anti-stress micronutrient, is important for immunocompetence. It is now very well known that the nervous system and the immune system are strongly interlinked. This also explains why mental stress has an immediate impact on the immunocompetence. Negative emotions, e.g. anger, rage and anxiety increase the susceptibility to infection.

Further Measures to Reduce Colds

In a flu epidemic, people should avoid crowds as much as possible. It is also important to wash the hands after shaking hands with a person suffering from a cold. Common cold viruses adhere to many objects, such as cookware, clothing etc.

Various herbal substances or phytopharmaceuticals can contribute to the improvement of immune competence, e.g. echinacea, taiga root, rose root, ginseng. Herbal remedies can be easily combined with micronutrients.

In general, a nutrient-rich, plant-based diet is recommended. A protein deficiency should be avoided unconditionally, whereby vegetable proteins are to be preferred.