Selenium’s Role in Immune Health

Selenium is an essential trace element with multiple roles in the human body including supporting the immune system’s ability to protect against infection.

Selenium is a mineral that is important for a group of proteins called selenoproteins, which have a few different functions in the body, ranging from helping our reproductive system function to storing selenium in the liver.  Some selenoproteins, called glutathione peroxidases, are important for the body’s antioxidant system, which protects DNA and cells from oxidative damage.  This includes protecting the body’s immune cells from damage ^{1, 2}.

Selenium also plays a role in activating immune cells ¹ and helping them function, such as assisting macrophages to more effectively destroy or engulf pathogens.  The role of selenium in the response to vaccines continues to be investigated ³.

Figure 1. A summary of selenium and immune responses¹.   © 2018 by the authors ¹. Licensee MDPI, Basel, Switzerland.  Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

Recommended Intakes

The recommended daily intake of selenium varies around the world ².  The Chinese Nutrition Society ⁶ set a Reference Nutrient Intake (RNI) of 60mg per day for adults.  Similarly, in the US the Institute of Medicine has set a Recommended Dily Allowance of 55mg per day ⁴.In addition, the European Food Safety Authority set an adequate intake (AI) of 70mg per day for adults ⁵.

Dietary Sources

Meats, eggs, nuts, seeds, seafood, and whole grains are good sources of selenium.

The selenium content of foods is linked to the selenium content of the soil (see ‘Deficiency’ section below).

Table 1. Selenium content of common foods in the diet ⁷

Deficiency

Selenium deficiency is expected to affect up to 1 billion people worldwide.  This deficiency primarily affects people in areas where the soil is low in selenium ⁷ and, as a result, the foods that grow in that soil are low in selenium.

The distribution of selenium in the soil is extremely uneven, with significant differences even within countries.  Regions with lower selenium intakes ⁸ include certain areas of New Zealand, China, and Italy, among many others.

In areas where the soil is rich in the soil, selenium deficiency is rare.  For example, the average daily intake of selenium in the US is almost twice the daily recommendation.  Certain regions of China, where selenium is plentiful in the soil, also have high intakes of selenium ⁹.

Excess Intakes

Selenium has a narrow window between adequate and toxic levels.  Getting too much selenium can lead to symptoms like gastrointestinal or neurological symptoms, hair loss, nausea, fatigue, among others ⁷.  For this reason, in the US a tolerable upper limit of selenium has been set at 400mg per day for adults ³ .  The EFSA recently revised their upper limit to 255mg per day for adults including pregnant and lactating women ¹⁰.  Lower limits are recommended for younger groups.

Selenium Supplementation

People who are deficient in selenium are shown to have impaired immune responses ², and studies show that reinstating selenium status through supplementation can improve the body’s ability to fight infection.  Those with adequate selenium intake through their diet are unlikely to see additional benefits.  A recent meta-analysis of selenium ¹¹ supplementation trials showed a very mixed picture of effects but no conclusive evidence of an beneficial effect on the immune system beyond the recommended dietary intake.

This article was publishing in March 2020 and updated on April 07, 2026.

• References
  1. Avery JC, Hoffmann PR. (2018)  Selenium, Selenoproteins, and Immunity.  Nutrients, 10: 1203.  DOI: 10.3390/nu10091203
  2. Bai S, Zhang M, Tang S, et al. (2024)  Effects and Impact of Selenium on Human Health, A Review. Molecules (Basel, Switzerland) 30: 50.  DOI: 10.3390/molecules30010050
  3. Meng H, Wang Y, Zhai Y, et al. (2024)  Unveiling the micronutrient-immunity puzzle in inactivated COVID-19 vaccination: A comprehensive analysis of circulating micronutrient levels and humoral responses in healthy adults.  J Med Virol 96: e29611.  DOI: 10.1002/jmv.29611
  4. Institute of Medicine. (2000)  Food and Nutrition Board. Dietary Reference Intakes: Vitamin C, Vitamin E, Selenium, and Carotenoids.  DOI: 10.17226/9810
  5. EFSA. (2014)  Scientific Opinion on Dietary Reference Values for selenium. EFSA J 12:3846.  Last accessed March 16, 2026.
  6. Chinese Nutrition Society. (2023)  Dietary Reference Intakes for China (2023) – A Summary Report.  Last accessed March 16, 2026.
  7. National Institute of Health. (2025) Selenium Fact Sheet for Health Professionals.  Last accessed March 16, 2026.
  8. FAO/WHO. (2001)  Report of a joint FAO/WHO expert consultation
     Bangkok, Thailand. Human Vitamin and Mineral Requirements.  Last accessed March 16, 2026.
  9. Blazina T, Sun Y, Voegelin A, et al. (2014)  Terrestrial selenium distribution in China is potentially linked to monsoonal climate.  Nat Comms 5: 4717.  DOI: 10.1038/ncomms5717.
  10. EFSA (2023) NDA EFSA Panel on Nutrition, Novel Foods and Food Allergens.  Scientific opinion on the tolerable upper intake level for selenium. EFSA J 21:7704.  Last accessed March 16, 2026.
  11. Filippini T, Fairweather-Tait S, Vinceti M. (2023)  Selenium and immune function: a systematic review and meta-analysis of experimental human studies.  Am J Clin Nutr 117: 93–110.  DOI: 10.1016/j.ajcnut.2022.11.007