Tag: Selenium

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Selenium and Thyroid Function

Data from a 2025 KiSel-10 sub-study analysis suggest that serum CD5L levels may be an additional biomarker for improved thyroid function. Serum CD5L levels may also be a suitable biomarker for adequate selenium status and for reduced mortality risk.

Illustration of thyroid gland
Adequate selenium intake is necessary for good thyroid function. Selenium is a component of the deiodinase enzymes that help convert inactive T4 thyroid hormone to active T3 thyroid hormone. Some selenoproteins act as antioxidants to protect the thyroid against oxidative damage. Selenium may help reduce the risk of autoimmune thyroid disorders.

Combined supplementation of elderly citizens with selenium and Coenzyme Q10 for 48 months significantly increased the level of circulating CD5L. The supplementation was associated with improved health-related quality of life and improved survival odds. Meanwhile, in the study’s placebo group, significantly higher cardiovascular mortality within 10 years was associated with low levels of circulating CD5L. The combined selenium and Coenzyme Q10 supplementation reduced the mortality risk. The active treatment in the KiSel-10 clinical trial was 200 mcg of selenium from selenium-enriched yeast and two times 100 mg of ubiquinone Coenzyme Q10 daily [Alehagen 2025]. read more

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Selenium and Heart Failure

Heart failure is a condition in which the heart no longer performs as well as it should. It affects millions of people in the United States and Europe. Heart failure is characterized by the following symptoms:

• shortness of breath
• build-up of congestion in the lungs
• accumulation of fluid in the lower extremities

What do we know about selenium status and the risk of heart failure?

Prof Urban Alehagen selenium and heart disease researcher
Prof Urban Alehagen’s KiSel-10 studies and sub-analyses have shown that selenium supplementation of elderly citizens low in selenium reduces the risk of heart disease mortality.

Low serum selenium levels are associated with increased risk of heart failure [Al-Mubarak 2021; Bomer 2020].

  • Selenium status below 70 mcg/L is regarded as selenium deficiency status [Al-Mubarak 2021; Bomer 2020].
  • Selenium status below 100 mcg/L is regarded as suboptimal status [Al-Mubarak 2021; Bomer 2020].
  • Both selenium deficiency and suboptimal selenium status are associated with increased risk of cellular dysfunction, oxidative stress, and chronic low-grade inflammation [Al-Mubarak 2021; Bomer 2020].

    • What do we know about selenium supplementation and heart failure?

    • Selenium supplementation of individuals with low selenium status may improve heart function and may reduce the need for hospitalization [Alehagen 2022].
    • Selenium supplementation of individuals with low selenium status may reduce the oxidative stress and systemic inflammation that increase the risk of heart failure [Alehagen 2022].

    Selenium and the Risk of Cardiomyopathy

    Myocardium is the medical term for the heart muscle. Cardiomyopathy is a disease or disorder of the heart muscle, often of unknown cause. Keshan disease is a form of cardiomyopathy that develops as a result of selenium deficiency and exposure to a strain of the coxsackievirus. The disease takes its name from Keshan County in northeastern China Its symptoms were first observed there. Keshan disease can result in heart failure [Zhou 2018]. read more

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    Selenium and Healthy Aging

    Healthy aging. How can we slow down and delay the aging process? Certainly, nutrition is one factor in anti-aging. Specifically, adequate intakes of the micronutrient selenium may prevent disease and may enhance healthy aging. Inadequate intakes of selenium, on the other hand, may result in diminished immune function and may accelerate the aging process [Bjorklund 2022].

    Professor Alehagen lectures about selenium and aging
    Professor Urban Alehagen was the lead researcher on the KiSel-10 study of the effect of combined selenium and CoQ10 supplementation on cardiovascular health in elderly citizen low in both substances.

    To a considerable extent, aging is associated with the oxidative damage caused by harmful free radicals to cells and DNA and proteins. Selenium through the work of antioxidant selenoproteins, e.g., the glutathione peroxidases and the thioredoxin reductases, improves our bodies’ antioxidant defenses against free radical damage [Bjorklund 2022; Avery & Hoffmann 2018]. read more

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    Selenium and Pregnancy

    During pregnancy, women need an increased intake of the trace element selenium. Low selenium intake and status in the pregnant mother will be reflected directly in poor selenium status in newborns [Filipowicz 2022].

    Newborn children can be low in selenium
    There is a strong correlation between the mother’s selenium status during pregnancy and the selenium status of the newborn child.

    Women living in regions with low selenium content in the soil and in the food most likely need a selenium supplement. A study conducted in selenium-poor central Poland has revealed that supplemental selenium in a dosage greater than 55 mcg/day can improve pregnant women’s selenium status [Filipowicz 2022].

    In the Polish study, one-third of the mothers reported self-initiated additional selenium intake. For the most part, these women took a multi-vitamin and mineral supplement. The tablet added, on average, 42 mcg of selenium to their diets daily. Even so, 79% of these women had serum selenium concentrations below 70 mcg/L (selenium deficiency levels). Moreover, 22% had serum selenium concentrations below 45.9 mcg/L (severe selenium deficiency levels) [Filipowicz 2022]. read more

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    Low Selenium Status in Elderly Adults

    Many elderly adults have low serum selenium concentrations. This is especially true in the United Kingdom and much of Europe and the Middle East [Stoffaneller & Morse 2015].  Now, a published report shows that over 80 % of the 85-year-old adults in a study in northeastern England had suboptimal serum selenium and selenoprotein P concentrations. Over 40 % had deficient selenium status, judged by reference values derived from studies of healthy adults in all age categories [Perri 2024].

    Elderly man
    Elderly study participants in England, men especially, were found to have suboptimal (80%) or deficient (40%) serum levels of selenium.

    Suboptimal serum selenium status was defined as 70 mcg/L or lower. Serum selenium deficiency was defined as 45 mcg/L or lower.

    The researchers observed a linear association between serum selenium levels and serum selenoprotein P (SELENOP) levels. SELENOP is the primary transport protein carrying selenium from the blood to the peripheral tissues. The findings in this study indicate that most study participants had suboptimal selenium intakes and status. Their diets were not sufficient to saturate the level of circulating SELENOP [Perri 2024]. read more

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    Selenium and Kidney Function

    Higher blood levels of the selenoprotein Glutathione Peroxidase-3 (GPx3) are positively associated with good renal function and are inversely associated with cardiovascular and all-cause mortality. Those are the main findings of a sub-analysis of data from the Swedish KiSel-10 study. The KiSel-10 study researchers investigated the effect of combined selenium and coenzyme Q10 supplementation on mortality in elderly community-living individuals low in selenium [Alexander 2024].

    Jan Alexander
    Dr. Jan Alexander, MD, PhD, specialist in toxicology and occupational medicine and department director, National Institute of Public Health, Oslo, Norway.

    GPx3 is a member of a family of eight known glutathione peroxidase antioxidant enzymes. GPx3 catalyzes the conversion of hydrogen peroxide into water. Accordingly, it reduces the extent of oxidative damage to cells. In addition to its oxidoreductase role, GPx3 plays a role in metabolism regulation, in cell growth, in apoptosis, and in signal transduction. In some cancers, it may act as a tumor suppressor [Zhang 2024]. read more

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    Selenium and Immune System Function

    Selenium is a micronutrient that we need for optimal immune system function. Selenium is important for the proper functioning of the leukocytes of the immune system. If we have low selenium status, we risk the following immune system dysfunctions [Sadler 2024]:

    • Overproduction of harmful free radicals
    • Unchecked systemic inflammation
    • Sub-optimal cellular signaling
    • Poor clearance of pathogens
    Healthy diet includes selenium
    A healthy diet includes adequate intakes of selenium. We need at least 100 mcg of selenium daily to achieve a serum selenium in the range 120-130 mcg/L. This serum level is required to optimize the concentration of selenoprotein P. Selenoprotein P is the primary transporter of selenium in the blood.

    Adequate intake of selenium is necessary to support an optimal immune system function. We need selenium to increase our resistance to disease. Selenium supplementation in individuals with low dietary selenium intakes can benefit the immune system [Sadler 2024]:

    • enhances antioxidant activity
    • promotes healthy gut microbiota
    • optimizes the innate immune response
    • improves the adaptive immune response

    In these ways, selenium supplementation of individuals with low selenium status prevents pathogenic diseases and autoimmune diseases and perhaps some cancers [Sadler 2024].

    Immune System Not Highly Prioritized for Selenium Transfer

    The distribution of selenium throughout the body reflects a hierarchical order. Even in times of low selenium intake, the body supplies selenium and selenoproteins to organs and tissues that are essential for survival and reproduction. For example, the brain and the endocrine glands are always highly prioritized [Schomburg 2020]. read more

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    Selenium and Cancer Treatment

    Adult cancer patients who have a selenium deficiency can benefit from selenium supplementation during their radiotherapy and/or chemotherapy. This is the conclusion from a 2024 systematic review. The researchers examined the pooled data from 12 clinical studies enrolling 2,483 patients. The reviewed studies investigated the use of selenium substitution therapy in adult cancer patients undergoing cancer treatment [Krannich 2024].

    Doctor advising cancer patient
    A review of 15 years of selenium supplementation has shown promising results in radiation therapy in tumor patients with a relative selenium deficit.

    The researchers defined selenium deficiency as serum or plasma selenium concentrations below 80 mcg/L or as whole blood selenium concentrations below 100 mcg/L. Furthermore, they regarded serum or plasma selenium levels over 130 mcg/L as replete status [Krannich 2024]. read more

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    Selenium and Cancer Prevention – the Evidence

    The evidence for the use of selenium supplementation in cancer prevention is still inconclusive. Rataan et al suggest that the fault may lie in the design of the existing studies. At least two factors have contributed to this lack of conclusive evidence:

    • the use of different compounds in the tests of selenium and cancer
    • the different blood selenium levels of the study participants at baseline
    Cancer patients
    Selenium supplementation of individuals with low dietary intakes of selenium may help prevent the development of certain types of cancer.

    As an example, Rataan et al cite the differences between the Nutritional Prevention of Cancer (NPC) trial and the Selenium and Vitamin E Cancer Prevention Trial (SELECT). In the NPC study, the researchers used a selenium-enriched yeast supplement. This yeast formulation contained mostly selenomethionine but also contained several other selenium species including Se-methylselenocysteine. In the SELECT study, the researchers used a 100% selenomethionine supplement. It now seems clear that the chemopreventive effect of selenium that was seen in the NPC study but not seen in the SELECT study must have come from some selenium species other than selenomethionine. The most likely chemopreventive selenium species is the Se-methylselenocysteine [Rataan 2022; Marshall 2017]. read more

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    Selenium Protects Against Methylmercury in Fish

    The health benefits of eating fish outweigh the health risks. This is especially true when we have sufficient dietary selenium intake and sufficient selenium status to 1) give a protective effect against methylmercury and 2) serve other biological purposes [Jorge 2024].

    Salmon dinner contains selenium
    Fatty fish such as herring, mackerel, and salmon are especially good sources of omega-3 fatty acids, protein, selenium, and vitamin D. Eating fatty fish regularly may reduce the risk of heart disease and stroke and enhance brain health.

    To varying degrees, all fish contain some mercury. The mercury in fish and seafood is primarily in the form of methylmercury. Unchecked, the methylmercury targets the nervous system. It disrupts cellular processes. Too much exposure can lead to a loss of muscular coordination and to a loss in cognitive function. Accordingly, the presence of mercury could be a health risk for people who eat fish regularly [Jorge 2024].

    Fortunately, many edible fish contain selenium in molar concentrations adequate to sequester the methylmercury in the fish and to render it less harmful. Ralston & Raymond have developed criteria for the calculation of selenium health based values. The calculations are based on the relative molar concentrations of mercury and selenium in various types of fish [Ralston 2016]. read more