Selenium Deficiency and Immune Function

Less systemic inflammation. Better immune function. Selenium is an essential trace element. Our cells cannot synthesize it. We must get it as a part of our diets. Adequate intakes are necessary for optimal immune system function.

Man in wheelchair at the beach
Autoimmune diseases develop when our own immune system malfunctions and attacks our cells. Then we suffer from autoimmune thyroid disorders, lupus, multiple sclerosis, psoriasis, rheumatoid arthritis or a hundred other autoimmune diseases.

Unfortunately, many of us live in regions with selenium-poor soil and selenium-poor crops and fruits. We do not get sufficient selenium from our food [Stoffaneller & Morse 2015]. Adequate selenium intake and status are vital. There are increased health risks associated with selenium deficiency.

What Defines Selenium Deficiency?

Data from the BIOSTAT-CHF observational cohort study indicate that serum selenium concentrations under 70 mcg/L constitute a deficiency status. Serum selenium concentrations under 100 mcg/L constitute a sub-optimal status [Bomer 2020]. read more

Selenium Status and Immune Function

Selenium is one of the micronutrients known to have an important and specific impact on immune system activity.

T-helper cell
Administration of selenium enhances the immune response of T-helper 1 cells and the stimulation of T cells. Depicted here: T-helper cell. Selenium also acts as a co-factor to achieve a more effective immune response to COVID vaccination.

In a 2022 review, Munteanu and Schwartz summarize the relevant research data on the modulation of immune function by micronutrients, including selenium and zinc [Munteanu 2022].

For selenium, the authors find the following evidence of a beneficial effect of selenium on immune system function:

  • Selenium, as a component of the amino acid selenocysteine, improves the synthesis of inflammatory mediators.
  • Selenium treatment leads to a decline in the gene expression of the pro-inflammatory cytokines IL-1 and TNF-alpha. This indicates that selenium has an anti-inflammatory effect in the body.
  • Selenium enhances the immune response of T-cells and T-helper 1 cells. T-cells work to destroy cells that have been infected by bacteria or viruses. Th1 cells are also responsible for fighting against bacteria and viruses.
  • Selenium supplementation increases the concentration of antibodies that enhance vaccine effects.
  • Selenium acts as a co-factor in the immunity that is mediated by the influenza vaccine. Selenium also serves as a co-factor to achieve a more effective immune response to COVID vaccination.
  • Selenium contributes to the defense against bacterial and vital pathogens through its effects on redox signaling activities.
  • -Selenium supplementation of patients with cancer increases antibody concentrations of the immunoglobulins IgA and IgG as well as increases the number of neutrophils.

Selenium – A Crucial Micronutrient for a Functional Immune System

Munteanu & Schwartz [2022] make the following additional points about an adequate supply of selenium:

  • Selenium improves not only in the functioning of the immune system but also the functioning of thyroid metabolism and the functioning of the cardiovascular system.
  • Selenium may play a role in the prevention of some forms of cancers.

Selenium and COVID-19

Munteanu & Schwartz [2022] report that selenium together with zinc exerts a protective role in COVID-19 patients. The combination of selenium and zinc is associated with a higher chance of survival. read more

Selenium and Viruses and Viral Infections

Viruses are very tiny germs that consist of genetic material (DNA or RNA) inside a protein coating. Unlike bacteria, viruses cannot survive on their own. They need host cells [MedlinePlus 2016].

When viruses invade the body, they hijack human cells and use the cells to reproduce themselves. The host immune system attempts to fight off the invasive viruses. If the immune system defense is not successful, then various viruses cause such infections as the common cold, influenza, and warts. Other viruses cause severe illnesses such as COVID-19, Ebola, and HIV/AIDS [MedlinePlus 2016].
Antibiotics are not effective against viruses. For some few viral infections, there are effective antiviral medicines. For others, vaccines may be an option. In any case, it is important to have a strong immune system to ward off or recover from viral infections.

Harmful free radicals play an important role in viral infections. The cells’ normal metabolism of oxygen generates reactive oxygen species as a by-product. At low and stable levels, these “free radicals” play a role in cell signaling and cell functioning. In the course of viral infections, however, the over-production of free radicals can overwhelm the body’s protective antioxidant systems and can cause oxidative stress [Guillen 2019]. read more

Selenium and Good Immune System Response

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.

Immunity spelled with Scrabble pieces
Selenium intake and status play a big role in the functioning of the immune system. Selenoproteins help to lower oxidative stress, reduce inflammation, and strengthen immune response to pathogens.

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]. read more

Selenium Status and Viral Infections

Selenium and viral infections, what do we know?

  • Selenium is a micronutrient that is essential for good health.
  • Low serum selenium status (below 85 microg/mL) and marginal serum selenium status (between 85 and 100 microg/mL) are common in many regions of the world, especially in many parts of Europe, the Middle East, China, and East Asia.
  • Selenium status is a key factor regulating the immune response to viral infections [Hiffler 2020].
  • Selenium status influences the immune system response to the severe acute respiratory syndrome corona virus infections [Bermano 2020].
  •  Selenium status is a risk factor that could well influence the outcome of a Covid-19 infection, particularly if the infected individuals have a sub-optimal or low selenium intake [Bermano 2020].
  • Selenium supplementation may limit the severity of Covid-19 infections, particularly in regions in which the selenium intake is low [Bermano 2020, Hiffler 2020].

Evidence for a Link Between Selenium Status and Viral Infection Severity

The early evidence came from study of the Keshan Disease in China – caused by the combination of the coxsackie B3 virus and low selenium status. By adding selenium to the soil fertilizer and by encouraging the use of selenium supplements, Chinese authorities have been able to reduce significantly the incidence of the disease [Bermano 2020].

Then came evidence from mouse studies that showed that there is increased virulence to coxsackie and influenza viruses in hosts with low selenium status [Bermano 2020].

Next came evidence that low selenium status, commonly seen in HIV-infected patients, is associated with reduced numbers of CD4 T cells and with increased disease progression and death rates [Bermano 2020]. read more

Selenium, Selenoproteins, and Antioxidant Systems

Disinfection materials
Low selenium status is associated with increased virulence of virus infections, with worse symptoms of heart failure, and with greater risk of some forms of cancer.

Oxidative stress is the bio-medical term for a lack of balance between 1) the production of harmful reactive oxygen and reactive nitrogen species and 2) the protective action of antioxidant systems. According to the news network of the Mayo Clinic, oxidative damage has been linked to several conditions such as Alzheimer’s, cancer, cataracts, diabetes, heart disease, macular degeneration, and Parkinson’s.

Free Radicals and Oxidative Damage

The reactive oxygen and reactive nitrogen species are popularly referred to as free radicals. They are molecules produced as natural by-products of metabolic processes and as a consequence of exposure to pollutants, to heavy metals, to industrial chemicals, to some drugs, to some forms of radiation including x-rays, and to cigarette smoking. read more

Selenium: Protection Against Viruses and Bacteria

Changing our behavior will help to protect us against viral infections, e.g. wearing a mask in public, washing our hands with soap and water or an alcohol-based hand rub, maintaining a distance of at least one meter from other people, avoiding crowded places, not touching our eyes, nose, and mouth, covering our mouth and nose with a bent elbow or tissue when we cough or sneeze, self-isolating if we have symptoms. But, equally important, we should make sure we have optimal selenium intakes and status. Selenium strengthens the immune system and protects against viral and bacterial infections.

In a 2015 review of the research literature, the selenium researchers Holger Steinbrenner and Helmut Sies from the Heinrich-Heine-University in Düsseldorf, Germany, give an overview of the effect of selenium status and supplementation in infectious diseases caused by viruses (e.g. HIV, influenza A virus, hepatitis C virus, polio virus, West Nile virus) and bacteria (e.g. M. tuberculosis, Helicobacter pylori) [Steinbrenner 2015].

  • Deficient intake and status of the essential trace element selenium are associated with viral and bacterial infections.
  • In the absence of adequate selenium status, otherwise benign strains of Coxsackie viruses and influenza viruses can mutate to highly virulent strains.
  • Nutritional supplementation with selenium supply to boost selenium status seems to confer health benefits for patients suffering from some viral diseases, in particular patients with HIV and influenza A virus infections.
  • Multi-micronutrient supplements containing selenium have been shown to improve several clinical and lifestyle variables in patients co-infected with HIV and Mycobacterium tuberculosis.
  • Selenium status may affect the function of cells of both adaptive and innate immunity.
  • Supplemental intakes of selenium are associated with the enhanced proliferation and differentiation of naive CD4-positive T lymphocytes toward T helper 1 cells, thereby supporting the acute cellular immune response.
  • Similarly, supplemental intakes of selenium are associated with the directing of macrophages toward the M2 type, thereby counteracting the excessive activation of the immune system with resulting host tissue damage.
  • Data from epidemiological studies and intervention trials, with selenium administered alone or in combination with other micronutrients have shown that selenium status and intake affect immune system functions.

Selenium Status and Intake

In her 2012 review article in The Lancet, the selenium researcher Margaret P. Rayman points out that selenium intakes average 40 micrograms/day in Europe compared with 93 micrograms/day for women and 134 micrograms/day for men in the United States.  Nutritional supplements can provide an additional 50–200 micrograms of selenium per day [Rayman 2012]. read more

Selenium and Viral Infections

Selenium deficiency is associated with increased virulence of viruses in human hosts.

Selenium and selenoproteins have a role to play in the protection of humans against viral infections [Méplan & Hughes 2020].

Viruses and viral infections are scary enough in and of themselves. Witness the effects of the current corona virus pandemic COVID-19.

Even more scary are the effects of nutritional deficiencies such as selenium deficiency on the body’s ability to fight off a viral infection.

Selenium Deficiency Associated with Increased Virulence of Viruses

Low selenium status, defined variously as serum selenium status below 70 micrograms per liter or below 85 micrograms per liter, is associated with the following deleterious effects of viral contagion [Méplan & Hughes 2020]:

  • The viral pathogens induce oxidative stress by generating more harmful free radicals. The result is oxidative damage to cells, proteins, and DNA.
  • The viral pathogens diminish the cells’ antioxidant defenses including diminishing the activity of the antioxidant seleno-enzymes, e.g. the glutathione peroxidases and the thioredoxin reductases.
  • The viral pathogens increase oxidative stress to the extent that it can induce mutations of the genomes of the attacking virus. The result is that the mutated viruses are more virulent than the initial viruses were. This increased virulence of mutated viruses has been seen in both coxsackie viruses and influenza viruses. The consequence of the increased virulence is to make the viruses more dangerous even to people with adequate selenium status.
  • The viral pathogens reduce the ability of the immune system to respond to the virus. This reduced immune response to viruses has also been seen in the response of selenium deficient humans to the HIV virus and the hepatitis B and C viruses.

Re selenium deficiency: Bomer et al reported more severe signs and symptoms of heart failure and poorer exercise capacity and poorer quality of life in heart failure patients with serum selenium concentrations below 70 mcg/L.  Rayman reported that serum and plasma levels below 85 mcg/L are associated with decreased survival in HIV-infected patients [Bomer 2019; Rayman 2012]. read more

We must not waste selenium

Selenium exists only in scarce quantities. Adequate dietary and supplemental intakes are vital for human health.  We need to use it carefully, and we need to begin to stockpile it for the use of future generations.

Selenium is a trace element.  It exists only in rare quantities in the world.  It is produced primarily as a by-product of the process of mining copper.  It is not recyclable.  It is very unevenly distributed in the soils of the earth.

Consequently, the availability of selenium in grasses and grains and, at the next stage of the food chain, in animals, varies considerably from region to region in the world. The human dietary intakes of selenium vary accordingly around the world.

Selenium a vital nutrient for humans
Selenium is a necessary micronutrient that our bodies do not produce.  We get our selenium primarily from our diets.  Selenium is important for good immune system function, good thyroid function, good reproductive function, and good protection of our cells’ DNA. read more

How we know that selenium supplementation is important

Selen supplementation, virus
Adequate intakes of selenium are needed to ensure the optimal functioning of the selenoproteins in the body. Selenoproteins provide protection against the development of cancer and heart disease; they are important for immune system defense; they protect against damage caused by heavy metals and chemical toxins and radiation. And, there is evidence that some of the selenoproteins have anti-viral properties.

Selenium?  A trace element?  You might well ask: How do we know that adequate amounts of dietary and supplemental selenium are important to us?
The first answer is: because we can see that selenium deficiency makes people sick.
A further answer is that we now know that selenium is an essential component of antioxidant enzymes.
And, on the basis of the results of randomized controlled trials, we know that selenium supplementation reduces the risk of cancer, reduces the risk of heart disease, and improves immune function.
Selenium is also very useful for reducing the toxic effects of heavy metals in the body.

Reason number one: Selenium-deficiency diseases
Keshan disease
In the 1960’s and 1970’s, thousands of people living in a region of China with selenium-poor soil, and, consequently, with selenium-poor food, died from the effects of a form of heart disease.  The disease, which took its name from Keshan county in the afflicted region of China, is characterized by inflammation and enlargement of the heart muscle and excess fluid in the lungs. The primary cause of the disease was selenium deficiency. read more