Our immune system needs support – Part 2

Other micronutrients such as vitamin E and the trace element selenium are also important

As an antioxidant and membrane stabilizer, vitamin E also plays an important role in protecting the immune system. The lipids and proteins of the cell membranes, whose integrity is essential for the immune response, are protected from the oxidative influences of free radicals by the fat-soluble vitamin E. The cells of the immune system are particularly dependent on absolutely intact cell surfaces: almost all effector mechanisms (e.g. antigen recognition and antigen presentation) are membrane-dependent and therefore fat-soluble antioxidants play a particularly important role in controlling membrane-mediated reactions of the immune system. Furthermore, vitamin E is known to have an enhancing effect on T-helper cell activity, immunoglobulin synthesis and an increase in phagocytosis activity. A vitamin E deficiency manifests itself in particular in a decrease in antibody production and reduced lymphocyte proliferation. Vitamin E also inhibits the synthesis of eicosanoids (prostaglandins, leukotrienes), which play a role in allergic and inflammatory processes and therefore has an anti-inflammatory effect. In the case of infections, there is also an increased release of eicosanoids, which in turn, in increased concentrations, weaken the functions of the immune system. This is another reason why vitamin E is said to have an immunoprotective effect.

Selenium is a component of the enzyme glutathione peroxidase, which is responsible for the breakdown of radical precursors such as peroxides. This trace element therefore also contributes to the protection of membranes and cell components from oxidative damage. Selenium also has a direct influence on the subpopulations of lymphocytes. The number of T-suppressor cells is reduced and an existing unfavorable T4 helper/T8 suppressor cell ratio can be shifted in favor of the T4 helper cells. This puts the immune system in a functionally better position. Selenium has a positive influence on phagocytosis as well as the proliferation of lymphocytes and antibody biosynthesis. An increase in natural killer cells and an increase in cytokine production (interleukins, interferons) has also been observed with selenium supplementation. Selenium deficiency reduces natural killer cell activity, lymphocyte proliferation and immunoglobulin synthesis. The antiviral defense decreases.

And what do secondary plant substances do?

Bioactive secondary plant substances such as those found in fruits, herbs, seeds and tubers are also of considerable importance for the body's own defenses and intact immune modulation. In addition to saponins, carotenoids and glucosinolates, polyphenols (flavonoids, phenolic acids) are particularly important. These are widespread in the plant kingdom as antioxidants, bitter substances and coloring components in fruits and leaves. In a randomized double-blind study conducted with women suffering from grass and birch pollen allergies, a mixture of polyphenols, zinc and vitamin A (with ß-lactoglobulin as a carrier) was tested for its effect. It was found that the accompanying allergic symptoms were reduced by around 40%. Another scientific study showed that a polyphenol-rich diet was able to reduce zonulin levels in the serum and improve intestinal mucosal permeability (keyword: "leaky gut"). In a comparative human study in which apples rich in polyphenols were used, there was evidence of an improvement in phagocytosis, complement activation, the production of immunoglobulins and B-cell-mediated immunity compared to the consumption of low-polyphenol fruits.

Immune-relevant medicinal plants with a long tradition in folk medicine, but also scientifically verified effects, include coneflower (Echinacea purpurea), ribwort plantain (Plantago lanceolata), thyme (Thymus vulgaris) and sage (Salvia officinalis). Echinacea has a broad spectrum of secondary plant constituents. These include alkamides, caffeic acid derivatives, flavonoids, polyacetylenes and glycoproteins. In a study with children, it was shown that the use of echinacea can reduce the rate of complications (e.g. pneumonia, sinusitis) when infections occur and also the use of antibiotics. In a clinical study with Covid-19 patients, a combination of echinacea and ginger was used for a period of one week in addition to the standard therapy (hydroxychloroquine). The significant improvement in concomitant symptoms (e.g. aching limbs, cough) in the intervention group compared to the test subjects who only received the standard preparation led to the recommendation in this study of the concomitant, combined use of the two medicinal plants for viral infections.

In 2014, ribwort plantain was named medicinal plant of the year by the University of Würzburg (Studienkreis Entwicklungsgeschichte der Arzneipflanzen). Ribwort plantain is not only known for its positive effect on the body's immune system, but also has astringent, anti-exudative and soothing effects and has proven particularly effective in treating diseases of the upper respiratory tract. The relevant substance classes here include mucilage, iridoids (isoprenoids) and phenylethanoids (phenethyl alcohol structure). Thyme is rich in essential oils such as thymol or carvacrol. These have antimicrobial, bronchospasmolytic, antiphlogistic and secretolytic effects, making this medicinal plant particularly suitable for colds and/or flu-like infections. Sage (Salvia officinalis) also has a high content of essential oils and is characterized by an antimicrobial, antifungal and antiviral effect. These medicinal plants are therefore not only ideal for supporting the immune system but also for preventing or treating infections.