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Vitamin C – Its Role in the Normal Function of the Immune System
Vitamin C, also known as ascorbic acid, is an essential nutrient involved in numerous physiological processes. Among other functions, it contributes to the activity of immune cells and helps protect cells against oxidative stress.
As an antioxidant, vitamin C helps protect cells against damage caused by free radicals. It is also involved in collagen synthesis, which is important for the normal functioning of the skin, blood vessels and other tissues.
The human body cannot synthesise vitamin C, so it must be obtained from the diet. Sources include peppers, citrus fruits, kiwifruit, blackcurrants, broccoli and other fruits and vegetables.
Supplementation may be helpful when dietary vitamin C intake is insufficient. However, high doses should not automatically be assumed to be more beneficial than amounts that meet the body's actual requirements.
Vitamin D – Its Importance for a Normal Immune Response
Vitamin D has functions that extend beyond calcium and phosphate metabolism. Its receptors are also found in cells involved in immune function, and the vitamin itself participates in the regulation of various cellular processes.
Vitamin D is synthesised in the skin in response to UVB radiation and can also be obtained from food. Dietary sources include oily fish, egg yolks and certain fortified foods. However, dietary intake alone may not be sufficient to meet the body's requirements.
The risk of inadequate intake depends on several factors, including the time of year, exposure to sunlight, dietary habits and individual circumstances. Decisions about supplementation should therefore take current recommendations and individual needs into account.
It is important to distinguish an adequate intake of vitamin D from the use of high doses without a clear justification. Excessive intake can disrupt calcium metabolism and pose a health risk.
Zinc
Zinc is involved in DNA and protein synthesis, cell division and the activity of numerous enzymes. It is also important for the normal development and function of immune cells.
Dietary sources include meat, seafood, dairy products, legumes, nuts and whole grains.
Inadequate zinc intake can impair normal bodily functions. Conversely, long-term intake of excessive amounts may lead to adverse effects, including impaired copper absorption.
Selenium
Selenium is a component of selenoproteins, including enzymes involved in protecting cells against oxidative stress. It also contributes to the normal function of the thyroid gland and the immune system.
The selenium content of food depends, among other factors, on the selenium concentration in the soil in which plants are grown or from which animal feed is obtained.
Supplementation may be justified in certain circumstances, but it should not result in excessive intake. The distinction between adequate and excessive amounts is important, so total selenium intake from all sources should be taken into account.
Probiotics and the Gut Microbiota – The Importance of Biological Balance
The gastrointestinal tract is an important interface between the body and the external environment. The intestines contain a diverse community of microorganisms known as the gut microbiota. These microorganisms contribute to processes such as nutrient metabolism and interact with the body's defence mechanisms.
Probiotics are live microorganisms that, when administered in adequate amounts, confer a documented health benefit on the host. Their effects depend on the specific strain, the dose used and the outcome being investigated. It should therefore not be assumed that all probiotic preparations work in the same way.
Scientific research investigates, among other things, the effects of specific strains on gastrointestinal function and selected health outcomes. However, findings relating to one strain or a particular clinical situation cannot necessarily be generalised to other preparations.
It is also worth remembering that everyday dietary habits influence the gut microbiota. Vegetables, fruits, legumes and whole grains provide dietary fibre, which can be utilised by intestinal microorganisms. Dietary variety is also important.
B Vitamins and Other Nutrients
The normal functioning of the immune system depends on the interaction of numerous metabolic processes. In addition to vitamins C and D, zinc and selenium, other nutrients also play important roles.
Vitamin B6 is involved in protein metabolism and immune function. Vitamin B12 and folate are essential for processes including DNA synthesis and cell division. Copper participates in numerous enzymatic reactions, while vitamin A contributes to the maintenance of normal mucous membranes and other tissues.
These nutrients should primarily be obtained through a balanced diet. Where deficiencies have been identified or requirements are increased, supplementation may help meet the body's needs.
However, correcting a deficiency should not be confused with providing additional health benefits to someone who already obtains sufficient amounts of a particular nutrient.
Authorised EU health claims relating to the normal function of the immune system exist for vitamins B6 and B12, folate, copper and vitamin A, provided that the applicable conditions of use are met.
Do More Supplements Mean Better Immunity?
No. The body requires an adequate supply of nutrients, but excessive intake does not necessarily provide additional benefits.
High doses of certain vitamins and minerals can cause adverse effects and may interact with medicines. This applies, among others, to vitamin D, zinc and selenium.
It is also important to remember that food supplements are not a substitute for a varied diet, appropriate medical assessment or treatment. They should not be presented as preventing or treating diseases unless such claims have been authorised under the applicable legal framework.
The most rational approach is to assess dietary habits, identify potential deficiencies and select supplements according to actual needs.
Everyday Habits as the Foundation of Normal Bodily Function
Supplementation is only one element of maintaining good health. It cannot replace basic habits that help keep the body functioning properly.
Several areas deserve particular attention:
- A varied diet – Regular consumption of vegetables, fruits, whole grains, protein sources and appropriate fats helps meet nutritional requirements.
- Sleep and recovery – Adequate sleep duration and quality are important for the normal functioning of many body systems.
- Regular physical activity – Exercise adapted to an individual's abilities supports overall fitness and metabolic health.
- Managing chronic stress – Habits that promote recovery, such as rest, a regular daily routine and relaxation techniques, can be beneficial.
- Adequate hydration – Adjusting fluid intake to the body's needs helps maintain normal physiological functions.
No single habit or supplement guarantees protection against infections. A comprehensive approach to health, tailored to age, lifestyle and individual circumstances, is what matters.
Conclusion
The normal functioning of the immune system depends on many interacting factors. An adequate intake of vitamins and minerals is one of the essential elements in maintaining its normal activity.
Vitamins C and D, zinc, selenium and certain B vitamins have authorised EU health claims relating to the normal function of the immune system. In the case of probiotics and omega-3 fatty acids, it is important to distinguish scientific findings about their biological properties from claims that may legally be used in food-related communications.
The primary goal of supplementation should be to complement the diet in a rational way that meets the body's needs, rather than to take the largest possible number of supplements.