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Selenium Supplementation and Polycystic Ovary Syndrome (PCOS)

Polycystic ovary syndrome (PCOS) occurs in 5 to 10% of women. It is the most common cause of infertility in women. PCOS is typically described by the presence of common symptoms: mild obesity, irregular periods or absence of a period, and signs of excessive androgen such hirsutism and acne. Most PCOS patients will have multiple cysts in the ovaries. More research into the effects of selenium supplementation on PCOS is needed.

Polycystic ovary syndrome (abbreviated PCOS) is a hormonal disorder with a prevalence of 5 – 10% in women of reproductive age.

  • The exact cause of PCOS is unknown.
  • Symptoms of PCOS include irregular periods, increased levels of male hormone, and failure of the ovaries to function regularly.
  • Excess insulin production and low-grade inflammation are thought to have an effect on the development of PCOS [Mayo Clinic].

Selenium: Effect on Mental Health, Hormonal Profile, Inflammation, and Oxidative Stress in Patients with PCOS

In a randomized controlled trial enrolling 60 women aged 18 – 40 years, daily co-administration of a probiotic supplement and 200 micrograms of selenium for 12 weeks was associated with the following outcomes [Jamilian 2018]:

  • significant improvement in Beck Depression Inventory scores, general health questionnaire scores, and depression anxiety and stress scale scores compared with the placebo
  • significantly reduced total testosterone levels, hirsutism, high-sensitivity C-reactive protein levels (a bio-marker for inflammation), and malondialdehyde levels (a bio-marker for oxidative stress) as well as significantly increased total antioxidant capacity and total glutathione (GSH) levels compared with the placebo

The researchers concluded that the co-administration of probiotics and selenium for 12 weeks to women with PCOS had beneficial health effects.

Selenium: Effect on Metabolic Profile in Patients with PCOS

In a randomized controlled trial enrolling 70 women aged 18 – 40 years, daily supplementation with 200 micrograms of selenium for 8 weeks was associated with the following outcomes compared with placebo [Jamilian 2015]: read more

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Selenium in Body Tissues and Physiological Processes

Professor Gerhard N. Schrauzer was the director of the Biological Trace Element Research Institute in San Diego, California. He led the way in the study of the biological functions of selenium, especially in relation to selenium’s cancer protective properties.

The biology of selenium in humans is complex.  What is known is that selenium is widely distributed in body tissues and in physiological processes [Wrobel].

Particularly of interest is the preferential maintenance of selenium concentrations in the brain, even in circumstances in which selenium stores are deleted in other organs such as the liver and kidneys [Wrobel].

What Does Selenium Do in the Body?

Dr. Wrobel, University of Miami Department of Biochemistry and Molecular Biology, lists the following functions of selenium and selenoproteins in the body:

  • Adequate levels of selenium are needed to modulate the function of the thyroid gland.
  • Selenium plays an important role in male and female fertility.
  • Selenium deficiency is associated with cardiac and skeletal muscle disorders, with changes in muscle fibers leading to the impairment of muscle contraction and to muscle atrophy.
  • Low levels of selenium are associated with impaired cognitive function and neurological disorders.
  • There exists an inverse relationship between selenium concentrations and the risk of coronary heart disease and the risk of certain types of cancer.
  • Low selenium levels are associated with high HIV mortality.
  • Selenium supplementation reduced the number of hospital admissions for HIV patients.

Selenium and the Prevention of Cancer

Epidemiological studies show generally that higher exposure to selenium is associated with a reduced risk of most forms of cancer.  For example, people living in higher soil selenium regions tend to have lower incidence of cancer [Wrobel]. read more

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Selenium and Brain Function

Brain cells are especially vulnerable to oxidative stress, which could be a factor in the pathology of neurodegenerative disorders. The danger of oxidative damage caused by free radicals (oxygen reactive species) is great because 1)  the neurons use large quantities of oxygen, 2) the brain has high iron content, 3) neuronal mitochondria produce large quantities of hydrogen peroxide, and 4) neuronal membranes are full of polyunsaturated fatty acids, which are susceptible to oxidative stress [Shichiri, 2014]. Adequate supply of selenium and synthesis of antioxidant selenoproteins are necessary to counteract the harmful effects of oxidative stress.
A review of the research literature on selenium and selenoprotein function in brain disorders reveals that selenium deficiency is associated with impaired cognitive function and impaired motor function [Pillai].

It is interesting to note that selenium concentrations are preferentially maintained in the brain even when the selenium concentrations in the blood circulation, in the liver, and in the skeletal tissues are depleted [Pillai].

Selenium supplementation may help to reduce the progression of the pathology of neurodegenerative diseases: Alzheimer’s, Huntington’s, and Parkinson’s [Pillai].

Selenium and Selenoproteins

What do we know about the trace element selenium and its incorporation into selenoproteins? read more

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Selenium and Coenzyme Q10 for Senior Citizens

Professor Urban Alehagen, Linköping University, Sweden, was one of the key researchers on the Q-Symbio clinical trial and has been the lead researcher on the KiSel-10 clinical trial. He has shown that joint selenium and Coenzyme Q10 supplementation of senior citizens with low selenium status reduces the risk of cardiovascular mortality and improves heart function.

The Swedish KiSel-10 Study provides randomized controlled trial evidence that a daily combination of an organic high-selenium yeast supplement and a pharmaceutical-grade Coenzyme Q10 supplement can reduce cardiovascular mortality, improve heart function, and increase health-related quality of life in senior citizens [Alehagen 2013].

Low blood selenium concentrations and higher risk of heart disease

Professor Urban Alehagen and a team of researchers from Linköping University investigated the blood selenium levels in 688 Swedish senior citizens.  The mean blood selenium level was 67.1 micrograms per liter, which is quite low but not surprising, given that Sweden is a country with selenium-low soil and selenium-poor foodstuffs [Alehagen 2016].

When the researchers adjusted for gender, smoking, coronary artery disease, diabetes, chronic obstructive pulmonary disease, and impaired heart function, they found that the quartile of senior citizens with the lowest level of blood selenium had a 43% higher risk of all-cause mortality and a 56% higher risk of cardiovascular mortality [Alehagen 2016]. read more

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Blood selenium concentrations and high-grade prostate cancer

A 2012 meta-analysis and systematic review has shown an inverse association between plasma/serum selenium levels and prostate cancer advanced prostate cancer in particular. Denmark is in a low-selenium region of the world, and the Danish population as a whole has low selenium intakes and sub-optimal blood selenium levels. Danish researchers have, accordingly, investigated the association between pre-diagnostic selenium levels and the risk of total, advanced, and high-grade prostate cancer. Pictured here: the Dannebrog, Denmark’s national flag.

Higher blood selenium concentrations and higher blood selenoprotein P concentrations are significantly associated with reduced risk of high-grade prostate cancer [Outzen].

The researchers defined “advanced” prostate cancer as ≥T3 or with a Gleason-score ≥7.  They defined “high-grade prostate cancer” as cancers having a Gleason score equal to or greater than 8.

Furthermore, in survival analyses, a higher pre-diagnostic level of plasma selenium is significantly associated with a lower risk of all-cause mortality in prostate cancer patients [Outzen].

Selenium and prostate cancer in the “Diet, Cancer, and Health” cohort

These are the conclusions from an analysis of the data from the Danish “Diet, Cancer, and Health” cohort.  The cohort consists of 27,179 men living in the greater metropolitan areas of Copenhagen and Aarhus who were recruited into the study.  They were aged 50 – 64 years and had no previous record of cancer at the time of recruitment [Outzen]. read more

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Selenium and prostate cancer: the toenail evidence

Meta-analyses have shown an inverse association between plasma/serum selenium concentrations and the risk of prostate cancer. The same inverse association has also been seen in three high-quality studies of toenail selenium concentrations and the risk of prostate cancer. The data from the Netherlands Cohort Study clearly show that higher toenail selenium is associated with significantly reduced risk of prostate cancer.

Analysis of data from the Netherlands Cohort Study shows that higher toenail selenium concentrations are associated with a substantial reduction in the risk of advanced prostate cancer.  Men in the highest quintile of toenail selenium had a statistically significant (p=0.001) 63% reduced risk of advanced (stage III-IV) prostate cancer compared to men in the lowest quintile of toenail selenium [Geybels].

Men in the highest quintile of toenail selenium concentrations had a toenail selenium level higher than 0.617 micrograms of selenium per gram of toenail.  Men in the lowest quintile of toenail selenium concentrations has a toenail selenium level lower than 0.469 micrograms of selenium per gram of toenail [Geybels]. read more

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Selenium supplementation and insulin resistance: a clinical study

The latest clinical evidence shows that selenium supplementation of older adults with 200 micrograms of a high-selenium yeast preparation for up to three years does not adversely affect pancreatic beta-cell function or insulin sensitivity.

Results from a clinical trial comparing 200 micrograms of selenium supplementation with placebo supplementation show no effect of the selenium supplementation on measures of insulin secretion and insulin action [Jacobs]. 

These results can be regarded as important evidence that selenium supplementation for up to three years in older individuals has no diabetes causing effects in humans [Jacobs].

The researchers who conducted the selenium and insulin resistance study concluded that the results of the study do not show a causal role for selenium in the development of insulin resistance or in the development of type-2 diabetes [Jacobs].

Research design of the selenium and insulin resistance study

Background: In 2016, researchers at the Arizona Cancer Center in Tucson reported on the results of the Selenium Trial [Thompson]. read more

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Selenium and the prevention of prostate cancer: meta-analysis

There are many risk factors associated with the development of prostate cancer: age, family history, geographic region, insulin growth factor, nationality, and race. One risk factor that merits investigation is the relationship between blood selenium concentrations and prostate cancer risk.

Quote: “Selenium most probably has a protective role against the development of prostate cancer and its progression to advanced stages. Therefore, selenium supplementation can be proposed for prevention of prostate cancer.”

These words are taken from the conclusion of a 2018 systematic review and meta-analysis of studies of the association between selenium and prostate cancer [Sayehmiri].

The meta-analysis is based on the data from 38 journal medical articles that included 36,419 prostate cancer cases and 105,293 healthy controls. There were 22 case-control studies, 6 cohort studies, and 10 randomized controlled trials included in the meta-analysis [Sayehmiri].

Selenium levels associated with risk of prostate cancer

The pooled relative risk from the 38 studies of the association of selenium concentration and prostate cancer risk showed a statistically significant 14% risk reduction with higher levels of blood selenium or toe nail selenium. read more

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Circulatory selenium concentrations and Alzheimer’s disease

Brain tissue produces many free radicals (reactive oxygen species). The oxidative stress caused by an imbalance between potentially harmful free radicals and antioxidants to neutralize them is associated with ageing and with the onset of Alzheimer’s disease. Reduced levels of the selenium-dependent antioxidant enzyme glutathione peroxidase correlate strongly with cognitive decline and the risk of Alzheimer’s disease.

Blood selenium concentrations are significantly lower in patients with Alzheimer’s disease compared to healthy controls.  This reduction in selenium concentration is directly associated with the observed reduced levels of the important antioxidant selenoprotein, glutathione peroxidase, in Alzheimer’s disease patients.

These are the conclusions of the authors of a 2017 meta-analysis of 12 case-control studies of selenium concentrations in Alzheimer’s disease patients and healthy controls.  The 12 case-control studies comprised 594 Alzheimer’s disease patients and 472 healthy controls [Reddy].

Selenium and Alzheimer’s disease meta-analysis

The results of the systematic review and meta-analysis revealed the following associations:

  • Significantly decreased selenium levels were seen in the blood circulation of Alzheimer’s disease patients as compared to healthy controls.
  • Decreased selenium levels were also seen in the red blood cells and cerebrospinal fluid of Alzheimer’s patients as compared to healthy controls.  However, the difference in selenium concentrations did not reach the level of statistical significance.
  • Age matching between the Alzheimer’s disease patients and healthy controls showed decreased selenium levels regardless of the age of the patients.  This is interesting because advanced age is considered a risk factor for Alzheimer’s disease.
  • Controlling for socio-economic, geographical, and environmental differences also showed the decreased selenium levels in Alzheimer’s disease patients compared to the healthy controls.
  • A direct association was seen between decreased selenium levels and glutathione peroxidase levels in Alzheimer’s disease patients.

What is glutathione peroxidase, and why is it important?

The glutathione peroxidases (abbreviated GPx) are a family of antioxidant enzymes (selenoproteins) that reduce and thus neutralize potentially harmful radicals like hydrogen peroxide and lipid hydroperoxides.  In so doing, the GPx enzymes lessen the extent of oxidative stress damage. read more

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Low serum selenium levels and increased cardiovascular mortality

A recent study has found a relatively high mortality risk in elderly Swedish subjects with low selenium status. Supplementation with a high-selenium yeast supplement and a Coenzyme Q10 supplement for four years resulted in significantly reduced risk of death from heart disease, better maintained heart function, and better quality of life for senior citizens. The beneficial effect of the supplementation has persisted through the 12th year of follow-up.

Low plasma/serum selenium concentrations are associated with increased risk of death from heart disease and increased risk of death from all causes.  Professor Urban Alehagen and a team of researchers at Linköping University in Sweden have investigated the relationship between low selenium levels and the risk of heart disease.

Selenium supplements suggested for adults with very low Se levels

The Swedish study shows that adults with a serum selenium concentration below 57 micrograms per liter are at significantly higher risk of death from all causes (43% increased risk) and death from heart disease (56% increased risk) [Alehagen 2016].
57 micrograms of selenium per liter of serum.  Wow!  That’s low.

These significant associations remained solid even after the researchers had adjusted for the effects of possibly modifying factors: read more