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Selenium from Selenium-Enriched Yeast

Selenium from selenium-enriched yeast supplements is more bioavailable than selenium from an inorganic source such as sodium selenite. Selenium from selenium-enriched yeast supplements also tends to be less toxic. These are the conclusions from a 2008 evaluation undertaken by a European Food Safety Authority (EFSA) scientific panel [EFSA 2008].

Glass of beer
Manufacturers use the yeast Saccharomyces cerevisiae — also known as brewer’s yeast — to produce selenium-enriched yeast supplements.

To quote directly from the report:

“Despite the higher bioavailability of selenium from organic sources such as selenium-enriched yeast, the toxicity of these organic forms has been shown in a number of studies in experimental animals to be lower than that of inorganic selenite or selenate.”

Study data indicate that organic selenium is more bioavailable than inorganic selenium. Studies in which different selenium preparations have been compared head-to-head point towards a higher bioavailability of selenium from yeast than from inorganic sources [Hadrup & Ravn-Haren 2021]. 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

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Selenium and Type 2 Diabetes

Selenium supplementation and the possible risk of developing type 2 diabetes, what do we know? This is a complex issue. Many different biological, hormonal, and environmental factors have an effect on the relationship.

Selenium and diabetes interrelationship
Observational evidence points to relevant sex differences in the selenium-diabetes interrelationship. There may be potential harmful effects in men living in selenium-rich areas and in men with high habitual selenium intake. Research shows potential benefits of selenium on diabetes risk in women selenium-deficient areas or in women with low selenium intake.

In a 2024 review, Demircan and a selenium research team headed by Prof Lutz Schomburg, Charité Berlin, investigated the current evidence for a relationship between selenium and type 2 diabetes. Recent evidence points to selenium intake and serum selenium status as relevant factors in the study of type 2 diabetes complications and prognosis.

Two studies based on data from the National Health and Nutrition Examination Survey (NHANES) in the United States have identified selenium intake and serum selenium status, respectively, as associated with the improved survival of type 2 diabetes patients [Demircan 2024]. read more

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Selenium and Graves’ Disease

Graves’ disease is an autoimmune disease. It is the most common cause of hyperthyroidism, i.e., overactive thyroid disorder. Ultimately, it is the overproduction of thyrotropin receptor (TRAb) antibodies that results in hyperthyroidism. Over time, Graves’ disease causes extensive damage to thyroid gland cells and tissues [Song 2023].

Thyroid system
In Graves’ disease, the thyroid gland produces too much thyroid hormone, a condition called hyperthyroidism. Attribution: Wikimedia Commons.

Oxidative stress appears to play an important role in Graves’ hyperthyroidism. Oxidative stress is the medical term for a disruption of the balance between harmful free radical oxidants and protective antioxidants. The increased production of reactive oxygen
radicals and inflammatory cytokines drives the development and progression of Graves’ disease [Song 2023]. read more

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Selenium and Vitamin D for Thyroid Health

Supplementation with selenium and vitamin D can improve the prognosis of type 2 diabetes mellitus and Hashimoto’s thyroiditis. Adding a daily dose of selenium and vitamin D to conventional diabetes medication can give significant health benefits [Yu 2024].

Selenium and Vitamin D for Type 2 Diabetes and Thyroid Disorder
A Chinese study suggests that combining conventional diabetes medicine with selenium and vitamin D supplements  reduces the levels of TSH and TPOAb and blood glucose and blood lipids in patients with concomitant type 2 diabetes and Hashimoto’s thyroiditis.

Researchers at Hunan University of Chinese Medicine, Hunan Province, China, recommend 100-200 mcg/day of selenium and 100 mcg/day of vitamin D for three to six months for patients with Hashimoto’s thyroiditis and especially for Hashimoto’s thyroiditis patients with concomitant type 2 diabetes [Yu 2024].

A 2024 study by Feng et al has shown that adding 200 mcg of selenium daily and 100 mcg of vitamin D to standard anti-diabetic drugs significantly improved thyroid function, thyroid antibodies, blood glucose, and blood lipids in type 2 diabetes patients who were also diagnosed with Hashimoto’s thyroiditis. read more

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Selenium Supplementation and COVID-19

There is, at present, an ongoing scientific debate about selenium supplementation and the possible prevention of COVID-19 disease. What is the evidence that selenium supplementation of individuals with sub-optimal selenium status might help to prevent the infection?

Margaret P. Rayman, selenium researcher
Margaret P. Rayman, Professor of Nutritional Medicine at the University of Surrey in the United Kingdom, is a long-time researcher into the effects of selenium and iodine on human health.

The answer from a group of longstanding selenium researchers is that selenium supplementation does not have “a sufficient direct antiviral effect to prevent infection.” Instead, selenium supplementation acts “by decreasing the harmful effects of the virus on the host” [Rayman 2024].

Selenium supplementation “does not necessarily prevent infection but rather decreases the severity and mortality resulting from the infection” [Rayman 2024]. The important thing to focus on is the interaction between the human host selenium status and infectious virus strain and virulence [Beck 2003]. read more