Why vitamin A should not be taken during illness.
Vitamin A helps strengthen the immune system, so it is better to take it for prevention. However, during illness, it may suppress the immune response.
With regular preventive intake, vitamin A reduces the likelihood of diseases and strengthens the immune system through the following mechanisms:
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Support for barrier functions. Vitamin A is essential for maintaining the integrity of the mucous membranes of the respiratory tract, intestines, eyes, and skin (the first line of defense of the body against viruses, bacteria, and toxins).
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Maturation of immune cells. Vitamin A participates in the differentiation of T and B lymphocytes—key immune system cells responsible for recognizing and destroying pathogens.
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Antioxidant protection. Vitamin A reduces oxidative stress and inflammation in the body, maintaining a balance between pro- and anti-inflammatory processes.
When an infection is already developing, the body initiates an active inflammatory response to destroy viruses and bacteria. An important role in this process is played by the so-called Th1 response—enhanced activity of macrophages, interleukins, and activation of inflammatory cytokines.
At this moment, vitamin A can:
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Shift the immune response towards a Th2 profile. Vitamin A tends to activate the so-called Th2 response—a milder, anti-inflammatory response aimed at tissue repair and reducing acute inflammation. However, during the acute phase of an infection, the suppression of the Th1 response hinders the body’s ability to effectively eliminate the pathogen.
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Slow down the activity of macrophages and NK cells. These cells are the "strike group" of the innate immune system. Suppressing their activity can slow down the body's clearance of the infection.
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Increase the risk of chronic forms of infections. Excessive softening of inflammation in the early stages of the disease can lead to incomplete destruction of the pathogen, its persistence, and the transition of the infection into a chronic phase.
