Selenium and Selenoproteins and Viral Infections

Selenium is an essential micronutrient. Humans cannot synthesize it. Therefore, we must get it from our diets. The selenium content of our diets depends on the richness or poorness of the selenium in the soil and the food. In fact, there are surprisingly large differences in selenium content in various regions of the world [Zhang 2020a].

Woman sneezing
Selenium deficiency and reduced selenoprotein expression have been associated with the pathogenicity of several viruses.

Selenium through its incorporation into 25 known selenoproteins is necessary for a range of biological functions. Zhang et al [2020a] list the following biological functions of selenium and selenium-derived selenoproteins:

  • Antioxidant function
  • Anti-inflammatory function
  • Anti-viral function
  • Cellular redox function
  • Immune cell function
  • Protection of the cardiovascular system
Selenoprotein Functions Relevant to Viral Infections

Selenium and selenium-derived selenoproteins such as the glutathione peroxidases (GPXs), the thioredoxin reductases (TXNRDs), and the endoplasmic-reticulum-associated selenoproteins influence viral pathogenicity. Among other things, these antioxidant selenoenzymes reduce the extent of oxidative stress generated by viral pathogens. Failure to counteract oxidative stress can result in mutations in the viral genome from benign to highly virulent strains [Zhang 2020a]. read more

Selenium Status and HIV Infections

HIV (human immunodeficiency virus) is still very much a public health concern. Deficiencies of certain micronutrients are known to play a role in the progression of HIV infections to AIDS (acquired immunodeficiency syndrome). In particular, adequate intakes of selenium are important because of selenium’s antioxidant and anti-inflammatory activities in HIV infection [Pourmoradian 2023].

Umbrella Study of Systematic Reviews of Selenium and HIV Studies

Symptoms of AIDS Poster
Selenium levels are often low in individuals infected with HIV virus. Selenium supplementation can slow the decline in CD4 cell counts, can reduce the risk of hospitalization, can prevent increases in the HIV-1 viral load, and can slow the progression of the infection to AIDS.

In a 2023 umbrella study of systematic reviews of studies of selenium in HIV patients, Pourmoradian et al found the following evidence:

  • Four reviews showed that selenium supplementation at the level of 200 mcg/day was effective in delaying CD4 decline in HIV-infected patients.
  • Three reviews showed that selenium supplementation at the level of 200 mcg/day significantly reduced HIV viral load.
  • The researchers suggested that the underlying mechanism of the selenium effect on HIV progression is the improvement of the immune response and the antioxidant defense system.
  • In particular, the selenium-dependent glutathione peroxidase (GSH-Px) enzyme system reduces the extent of oxidative stress, indirectly strengthens the immune system, and slows the progression of the disease.

Note: CD4 cells are lymphocytes that help to coordinate the immune response to infections. If an HIV patient’s CD4 cell count falls below 200 cells per cubic millimeter of blood, then the HIV infection is considered to have progressed to the AIDS stage. In healthy individuals, the CD4 count will be between 500 and 1,600 cells/cubic millimeter of blood. read more

Selenium Status and the Risk of Gestational Diabetes

Lower selenium status during pregnancy means there is a greater risk of developing gestational diabetes [Hamdan 2022; Xu 2022]. Three different selenium biomarkers in early and late pregnancy show a quite strong association of selenium with 1) the risk of developing gestational diabetes mellitus and 2) the birth of large for gestational age offspring [Demircan 2022].

Storks on a nest
Low maternal selenium status is strongly associated with an increased risk of gestational diabetes and with an increased risk of large for gestational age offspring.

The Mayo Clinic defines gestational diabetes as being diagnosed with diabetes for the first time during pregnancy. Gestational diabetes is like other forms of diabetes in that it affects how well the cells use glucose. It causes high blood sugar levels that can affect the mother’s health and the baby’s health [Mayo Clinic 2023]. read more

Selenium Exposure Studies

Selenium exposure in the diet and in supplements: in this review article, we summarize the key outcomes of the best selenium exposure studies.

Optimal Selenium Intake and Status

In his review of the available research literature, Professor Urban Alehagen, Linköping University, Sweden, concluded that a daily intake of 100–150 mcg of selenium per day is required.

This is the intake level that enables an optimal expression of the important selenoprotein P that transports selenium from the liver to peripheral tissues [Alehagen 2022].  For other selenoproteins to be optimized, i.e., to be fully expressed, Prof. Alehagen argues that selenium status of approximately 120 mcg/L when measured in red blood cells is necessary [Alehagen 2022]. read more

Hashimoto’s Disease Patients Benefit from Selenium Supplementation

Hypothyroidism is the medical condition caused by an underactive thyroid gland that is not producing sufficient quantities of thyroid hormones. It is the failure of the thyroid gland to function normally.

Jan Olav Aaseth
Endocrinologist Jan Aaseth, M.D., Ph. D., ERT, explains that, in Norway, the diagnosis of Hashimoto’s disease is made after a clinical examination that involves determination of the patient’s circulating levels of the thyroid hormone thyroxine (T4), thyroid stimulating hormone, and thyroperoxidase antibodies [Aaseth 2022].
The most common form of hypothyroidism is related to Hashimoto’s disease. Hashimoto’s disease is an autoimmune disorder most common among middle-aged women. Symptoms include anxiety, dry skin, fatigue and lethargy, muscle aches and muscle stiffness, negative mood, sensitivity to cold, slow thinking and poor memory.

The standard treatment for Hashimoto’s disease is twofold:

1) treatment with a synthetic hormone called levothyroxine, which works like the T4 hormone that is naturally produced by the thyroid gland read more

Serum Selenium Levels Predict Breast Cancer Prognosis

Research done in southern Sweden shows that three blood biomarkers of selenium availability correlated inversely with mortality from breast cancer. The lower the three selenium biomarker levels, the higher the mortality [Demircan 2021].

Breast cancer awareness
Assessment of selenium status at the time of breast cancer diagnosis identifies patients at exceptionally high risk for a poor prognosis. They are breast cancer patients with low levels of selenium, selenoprotein P, and glutathione peroxidase in their blood.

The blood biomarkers are:

  • Total selenium
  • Selenoprotein P
  • Glutathione peroxidase 3

Breast cancer patients with blood concentrations of these three selenium biomarkers in the highest quintile had significantly better chances of survival compared with patients whose blood levels of these substances were in the lowest quintile [Demircan 2021].

Breast cancer patients with low selenium status according to these three biomarkers had the highest mortality risk with an overall survival probability of approximately 50% after 8 years. The difference in survival between the breast cancer patients in the lowest selenium quintile compared to breast cancer patients with at least one biomarker in the highest quintile was especially notable [Demircan 2021]. read more

Selenium Deficiency and Heart Failure

Heart failure – the inability of the heart muscle to pump a sufficient quantity of blood out to the body – is a debilitating disease, resulting in shortness of breath, congestion in the lungs, and pooling of blood in the lower extremities. Heart failure is equivalent to diminished quality of life.

Depiction of a mitochondrion. The mitochondria in our cells convert energy sources such as fatty acids, glucose, and ketones into ATP energy molecules. Sufficient intakes of micronutrients such as selenium, Coenzyme Q10, and zinc are important for mitochondrial energy production and for antioxidant protection of cells, lipids, proteins, and DNA.

The prognosis for heart failure is poor, and the available medical therapies for patients with heart failure are inadequate. New treatment strategies are needed [Mortensen 2015].

Yin et al have analyzed the data from 39,757 adults in a cross-sectional study from the 2005–2018 US National Health and Nutrition Examination Survey. Their findings suggest that high levels of combined dietary antioxidant micronutrients are associated with decreased prevalence of various forms of cardiovascular disease and that selenium has the greatest contribution to this association [Yin 2022]. read more