In people with selenium deficiency (variously defined as serum selenium status below 60 mcg/L or 70 mcg/L), the responses of the innate and adaptive immune systems may be impaired.
Selenium deficiency can lead to an immune-incompetence that is associated with increased susceptibility to infections [Avery & Hoffmann 2018; Hiffler et al. 2020].
In cell culture models, in rodent models, in livestock and poultry studies, and in human studies, researchers have found evidence that adequate levels of dietary selenium and the efficient incorporation of selenium into selenoproteins are important for immune system function [Avery & Hoffmann 2018].
Studies of selenium supplementation to boost immunity against pathogens have not provided entirely clear-cut results; however, selenium and selenoproteins do play a role in regulating immune cell functions. Dysregulation of these immune cell processes can lead to inflammation and immune-related diseases [Avery & Hoffmann 2018].