Selenium is a micronutrient that we need for optimal immune system function. Selenium is important for the proper functioning of the leukocytes of the immune system. If we have low selenium status, we risk the following immune system dysfunctions [Sadler 2024]:
- Overproduction of harmful free radicals
- Unchecked systemic inflammation
- Sub-optimal cellular signaling
- Poor clearance of pathogens
Adequate intake of selenium is necessary to support an optimal immune system function. We need selenium to increase our resistance to disease. Selenium supplementation in individuals with low dietary selenium intakes can benefit the immune system [Sadler 2024]:
- enhances antioxidant activity
- promotes healthy gut microbiota
- optimizes the innate immune response
- improves the adaptive immune response
In these ways, selenium supplementation of individuals with low selenium status prevents pathogenic diseases and autoimmune diseases and perhaps some cancers [Sadler 2024].
Immune System Not Highly Prioritized for Selenium Transfer
The distribution of selenium throughout the body reflects a hierarchical order. Even in times of low selenium intake, the body supplies selenium and selenoproteins to organs and tissues that are essential for survival and reproduction. For example, the brain and the endocrine glands are always highly prioritized [Schomburg 2020].
In this hierarchical supply of selenium in times of deficiency, the immune system does not have priority at a high level. Accordingly, in individuals with low selenium status, there is the risk of not being able to express fully the selenoproteins that are needed for a proper and adequate immune response to challenges [Schomburg 2020].
Most likely, there are vital housekeeping selenoproteins that do not get synthesized and distributed in individuals with low selenium intakes and low selenium status. These marginally supplied individuals do not have a functioning immune system that protects them against oxidative damage and chronic inflammation and environmental challenges [Sadler 2024; Schomburg 2020].
Potential Benefits of Selenium Supplementation
In their 2024 review article, Sadler et al list the following potential benefits of selenium supplementation in low-selenium-status individuals:
- Antioxidant defense
- Decrease in inflammation
- Reduction of auto-antibody production
- Enhancement of antibody production and immune responses against pathogens
Conditions Affected Positively by Selenium Supplementation
Sadler et al discuss the following health conditions that selenium supplementation may protect against:
- Reduction in systemic inflammation
- Stimulation of the immune system against pathogenic bacteria
- Improvement in health outcomes during infections
- Reduction in the mutation rate of viruses during infections
- Improvement in microbiome resilience
- Increase in the quantity of beneficial bacteria in the gut
- Improvement in gut barrier function
- Enhancement of Short-Chain Fatty Acid (SCFA) production
- Improvement of health in individuals with autoimmune disorders such as autoimmune thyroiditis and ulcerative colitis
Selenium Protection of the Immune System
We need an adequate supply of antioxidant selenoproteins to regulate
the immune system’s activities. We need antioxidants to deal with
the excessive production of harmful free radicals. An imbalance between harmful free radicals and antioxidants results in lipid peroxidation of cell membranes, in DNA damage, and in protein degradation. This oxidative damage, in turn, can adversely affect immune function by damaging leukocytes and lymphoid tissues [Sadler 2024].
Note: Leukocytes are white blood cells involved in the innate immune response to bacterial and fungal pathogens. The different types of leukocytes include lymphocytes, macrophages, monocytes, natural killer cells, neutrophils, and others.
Interestingly, one important way that leukocytes kill pathogens is by generating free radicals that damage the pathogens. Furthermore, inflammation is a part of our biological response to pathogens. Selenoproteins also play a role in regulating the processes of oxidative stress and inflammation.
Conclusions: Selenium Needed for Proper Immune Function
We need an adequate supply of selenium and selenoproteins for optimal immune function and resistance to disease.
We need selenium and selenoproteins to control and regulate antioxidant and anti-inflammatory processes.
Sources
Larsen C, Winther KH, Cramon PK, Rasmussen ÅK, Feldt-Rasmusssen U, Knudsen NJ, Bjorner JB, Schomburg L, Demircan K, Chillon TS, Gram J, Hansen SG, Brandt F, Nygaard B, Watt T, Hegedus L, Bonnema SJ. Selenium supplementation and placebo are equally effective in improving quality of life in patients with hypothyroidism. Eur Thyroid J. 2024 Jan 1;13(1):e230175.
Sadler RA, Mallard BA, Shandilya UK, Hachemi MA, Karrow NA. The Immunomodulatory Effects of Selenium: A Journey from the Environment to the Human Immune System. Nutrients. 2024 Sep 30;16(19):3324.
Schomburg L. The other view: the trace element selenium as a micronutrient in thyroid disease, diabetes, and beyond. Hormones (Athens). 2020 Mar;19(1):15-24.
The information presented in this review article is not intended as medical advice. It should not be used as such.