Selenium Deficiency Due to Diet, Pregnancy, Severe Illness, or COVID-19—A Preventable Trigger for Autoimmune Disease

Abstract

The trace element selenium (Se) is an essential part of the human diet; moreover, increased health risks have been observed with Se deficiency. A sufficiently high Se status is a prerequisite for adequate immune response, and preventable endemic diseases are known from areas with Se deficiency. Biomarkers of Se status decline strongly in pregnancy, severe illness, or COVID-19, reaching critically low concentrations. Notably, these conditions are associated with an increased risk for autoimmune disease (AID). Positive effects on the immune system are observed with Se supplementation in pregnancy, autoimmune thyroid disease, and recovery from severe illness. However, some studies reported null results; the database is small, and randomized trials are sparse. The current need for research on the link between AID and Se deficiency is particularly obvious for rheumatoid arthritis and type 1 diabetes mellitus. Despite these gaps in knowledge, it seems timely to realize that severe Se deficiency may trigger AID in susceptible subjects. Improved dietary choices or supplemental Se are efficient ways to avoid severe Se deficiency, thereby decreasing AID risk and improving disease course. A personalized approach is needed in clinics and during therapy, while population-wide measures should be considered for areas with habitual low Se intake. Finland has been adding Se to its food chain for more than 35 years—a wise and commendable decision, according to today’s knowledge. It is unfortunate that the health risks of Se deficiency are often neglected, while possible side effects of Se supplementation are exaggerated, leading to disregard for this safe and promising preventive and adjuvant treatment options. This is especially true in the follow-up situations of pregnancy, severe illness, or COVID-19, where massive Se deficiencies have developed and are associated with AID risk, long-lasting health impairments, and slow recovery.

Pronounced Trace Element Variation in Follicular Fluids of Subfertile Women Undergoing Assisted Reproduction

“…It can be assumed that there are similar mechanisms operating in FF in order to tightly control and limit Se status and selenoprotein levels, as both GPX3 and SELENOP were successfully detected in FF and correlated linearly to serum levels. However, the optimal concentrations in FF are unknown, as the samples analyzed were derived from European women with insufficient habitual intake, much in contrast to, e.g., subjects residing in North America where Se intake is higher due to better soil Se status [49,50].…”

Selenium: An Element of Life Essential for Thyroid Function

“…It is known that patients with thyroid disease (including hypothyroidism, subclinical hypothyroidism, autoimmune thyroiditis and enlarged thyroid) have reduced Se levels [ 65 ]. Thus, many trials, especially those conducted in geographical areas with diffuse low or borderline Se status in the population, aimed to assess whether Se supplementation may affect the evolution of thyroid immune diseases [ 66 , 67 ]. Overall, available studies suggest that Se supplementation may induce a decrease in circulating thyroid autoantibodies.…”

“…Overall, available studies suggest that Se supplementation may induce a decrease in circulating thyroid autoantibodies. However, since data are inconsistent due to patient number heterogeneity, different forms of Se supplements, duration of the supplementation, instrumental evaluation of thyroid function and serum Se measurement, they may not demonstrate a definitive relationship [ 67 ]. Moreover, possible interventions could be focused on patients residing in areas with low Se availability or with low- or sub-optimal Se levels, which can particularly benefit from this supplementation, avoiding adverse consequences associated with a high Se status.…”

Relationship between Vitamin D Status and Antibody Response to COVID-19 mRNA Vaccination in Healthy Adults

“…Human health, and in particular the immune system, is highly dependent on an adequate supply of a number of micronutrients, including vitamins C and D [ 1 ] and the essential trace elements zinc [ 2 ] and selenium [ 3 ]. During the COVID-19 pandemic, vitamin D supplementation is frequently implemented, both self-administered and on the advice of medical professionals, as well as for experimental purposes in clinical trials [ 4 , 5 ].…”