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Selenium and Type 2 Diabetes

Type 2 Diabetes. Some news reports have suggested that high selenium intakes and status may be potential risk factors for the development of type 2 Diabetes mellitus. However, current data show that supplemental selenium does not cause diabetes [Schomburg 2020].

Diabetes symptoms
It seems likely that diabetes causes elevated blood selenium levels rather than the other way around [Schomburg 2020].
Two large randomized controlled trials using selenium supplements have shown no diabetes risk caused by 1) a selenomethionine product [Lippman 2009] and 2)   a selenium-enriched yeast product [Thompson 2016; Jacobs 2019]. In neither study was there any significant risk of diabetes  at the recommended dosage, not even among selenium-replete individuals of various ages and both genders [Schomburg 2020].

Moreover, in the Selenium Trial, the researchers saw no causal role for selenium in the development of insulin resistance or diabetes. Instead, they observed decreased fasting blood glucose levels in the selenium supplemented group compared to the control group [Jacobs 2019]. read more

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Selenium Protects Against Cadmium Poisoning and Atherosclerosis

Cadmium leaking from iron water pipes into drinking water may be a primary cause of increased risk of atherosclerosis – the increased risk of a buildup of plaque on the inside of the artery walls with inflammation as a consequence. This is the thesis of the Danish cardiologist Anton Dorph-Petersen.

Heart attack
Cadmium from drinking water accumulates in the body and causes damage to the layer of cells lining the inside of arteries, leading to a buildup of plaque and to increased risk of atherosclerosis and heart attack. Cadmium is a heavy metal that is found everywhere in the earth. Cadmium accumulates primarily in the liver and kidneys with toxic effects on the kidneys in particular. People with insufficient selenium and iron accumulate more cadmium. Cadmium takes a long time to be eliminated from the body. Iron water pipes and cigarette smoking are significant sources of cadmium in the body.

Dr. Dorph-Petersen asserts that the danger of cadmium toxicity is greatest in regions of the world in which the selenium content of the soil and plants is low and in regions of the world in which there is low dietary intake of selenium containing fish [Dorph-Petersen 2017].

Let me lay out Dr. Dorph-Petersen’s reasoning step by step. His hypothesis has not yet been verified by clinical trials.

However, we do know from a survey of 15,689 study participants in the US that low blood selenium and high blood cadmium are independent risk factors for heart failure. read more

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Selenium and Radiation Therapy for Cancer Patients

Cancer patients tend to have reduced serum selenium concentrations compared to healthy controls. Adjuvant selenium supplementation improves the protection of healthy tissue in tumor patients undergoing radiation therapy [Muecke 2018].

Cologne cathedral in Germany
15 years of experience with adjuvant selenium supplementation in radiation oncology in Germany has yielded a solid knowledge database. As a result,  some radiation oncologists measure the patient’s selenium levels during therapy and compensate in cases of selenium deficiency. Even so, it is important to remember that selenium status is  a relatively small piece in the bigger puzzle of therapeutic success in radiation oncology.

In a 2018 review of 15-years of experience with selenium supplementation in radiation oncology, Muecke et al [2018] reported on two randomized controlled trials. The researchers observed positive effects of the supplemental selenium and no adverse effects in the patients undergoing radiation therapy:

  • 81 patients with uterine cancer
  • 39 patients with head and neck tumors
Selenium Deficit in Cancer Patients

In the majority of the tumor patients (carcinomas of the uterus, head and neck, lungs, rectum or prostate) whom they examined, German researchers found a relative selenium deficit in whole blood or serum [Muecke 2018]. read more

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Selenium and Systemic Oxidative Stress

Oxidative stress. A new study shows that selenium supplementation together with Coenzyme Q10 supplementation reduces the levels of systemic oxidative stress in the body.  In the study, the reduction of systemic oxidative stress is significantly associated with a reduction in the risk of death from cardiovascular diseases [Dunning & Alehagen 2023].

Prof Urban Alehagen
Prof. Urban Alehagen, lead researcher on the KiSel-10 Study, the study that has shown that combined selenium and Coenzyme Q10 supplementation reduces oxidative stress and inflammation levels, improves heart function, and reduces the risk of cardiovascular disease mortality.

Oxidative stress: An imbalance of harmful free radicals vis-à-vis protective antioxidants leads to oxidative damage to DNA, lipids, and proteins in the body and to a disruption of redox signaling processes in the cells [Dunning & Alehagen 2023].

In a 2023 KiSel-10 sub-analysis, Prof. Urban Alehagen and his research colleagues investigated the level of free thiols in the serum of elderly study participants taking 200 mcg of selenium and 200 mg of Coenzyme Q10 daily for 48 months [Dunning & Alehagen 2023]. read more

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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

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Selenium Supplementation for Vegetarians and Vegans

Vegetarians and vegans, do they get enough selenium in their diets? It is an important question because the number of vegetarians around the world is growing for ethical and environmental reasons. How do we measure selenium status in various groups of people?

Vineyard in Germany with selenium-poor soil
The arable land in much of Europe contains a sub-optimal content of selenium, meaning that the plants grown there are also poor in selenium. Pictured: A vineyard in Germany.

Selenium is an essential trace element. Essential means that we have to get it from our food or from supplements. The human body does not synthesize selenium. What the body does synthesize is the selenoproteins, of which selenium in the amino acid selenocysteine is a key active component.

Particularly in much of Europe and the Middle East, the soil and the plants have relatively poor selenium content. In many countries, the farm animals are supplemented with selenium to improve their nutritional intakes and their health and to avoid selenium deficiency syndromes. read more

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Selenoprotein P – Selenium Transport Protein and Biomarker of Selenium Status

Selenium and selenoproteins are essential to human health [Rayman 2012]. However, selenium intakes from food vary considerably from region to region in the world, depending on how rich or poor the soil and the foodstuffs are.

Selenium researcher Professor Urban Alehagen
Professor Urban Alehagen realized that the low selenium content of the soil in Sweden and in much of Europe results in wide-spread low dietary selenium intake and selenium deficiency. In the Swedish KiSel-10 Study, the average serum selenium concentration was a quite low 67 mcg/L.

For example, widespread suboptimal selenium status has been reported throughout Europe, the UK, and the Middle East [Stoffaneller & Morse 2015]. In contrast, the soil and the foodstuffs in much of the United States and Canada have a much higher selenium content than is the case in Europe. Serum selenium levels of US citizens are generally above 120 mcg/L. In many European countries, the corresponding serum selenium levels are 90 mcg/L on average [Alehagen 2016].

  • The best estimate for serum selenium status that is sufficient for good health is around 125 mcg/L [Winther 2020, fig. 3].
  • Serum selenium levels below 70 mcg/L are indicative of selenium deficiency [Bomer 2020].
  • Serum selenium levels below 100 mcg/L are indicative of sub-optimal selenium status [Al-Mubarak 2021].
Selenoprotein P as the Major Selenium Transport Protein

Dietary selenium is incorporated into the amino acid selenocysteine, which becomes an integral component of 25 selenoproteins. The best known selenoproteins are the glutathione peroxidases, thioredoxin reductases, and
iodothyronine deiodinases [Schomburg 2019]. read more

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Selenium Supplementation Increases Serum Sirtuin1 Concentrations

Daily supplementation with 200 mcg of selenium and 200 mg of Coenzyme Q10 for four years has resulted in significant increases in serum SIRT1 concentrations. In the parallel placebo group, the serum SIRT1 concentrations decreased significantly [Opstad, Alehagen 2023].

Selenium Researcher Professor Jan Aaseth
Professor Jan Olav Aaseth, Inland Norway University of Applied Sciences, is the guest author on this review article. Dr. Aaseth has written extensively about selenium in health and disease. He is one of the co-authors on the Sirtuin1 study summarized here.

This is the latest evidence from the KiSel-10 Study in which researchers randomly assigned elderly community-living Swedish men and women, average age: 76 years, 49% female, to a combined selenium and Coenzyme Q10 treatment group or to a placebo group [Alehagen 2013].

In earlier papers, the KiSel-10 Study researchers have reported beneficial effects of the combined supplementation of the elderly Swedish citizens with low baseline selenium levels [Alehagen 2022; Opstad 2022]: read more

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Selenium Supplementation and Chemotherapy in Cervical Cancer Patients

Selenium yeast supplementation administered concurrently with chemotherapy and radiation therapy effectively increased blood selenium levels in cervical cancer patients with inadequate selenium status. The selenium yeast supplementation was used as an adjuvant treatment to the standard chemotherapy and radiation therapy. It significantly decreased the hematologic toxicity of the chemoradiotherapy [Yang 2023].

Cancer and selenium
Each year, worldwide, half a million women are diagnosed with cervical cancer, and 300 000 die from the disease. In most cases, the human papilloma virus is the cause of the disease [Cohen 2019]. The trace element selenium has antiviral properties. Cell studies and mouse studies of cervical cancer have shown that different selenium species have anticancer effects in cervical cancer induced by human papilloma virus or by chemical carcinogens [Jablonska 2021].
In a randomized controlled trial, researchers randomly assigned 104 patients diagnosed with stage IIB cervical cancer receive 100 mcg selenium yeast tablets (n=50) or matching placebos twice daily (n=54) for five weeks [Yang 2023].

All patients in both groups received the standard treatment including pelvic external irradiation, concurrent five cycles of chemotherapy, and brachytherapy [Yang 2023]. read more

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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