Selenium Vital for Good Health

Gerhard N. Schrauzer
Dr. Gerhard N. Schrauzer (1933-2014) was the Director of the Biological Trace Element Research Institute in San Diego and the founder and editor-in-chief of the Biological Trace Element Research journal. He was a pioneer in the study of selenium’s biological functions. He was one of the first researchers to realize that selenium has positive effects on human and animal health.

Quote: “Pluck almost any cell from your body, and it will have a million or more selenium atoms in it, yet until recently nobody had any idea what they were there for. We now know that selenium makes two vital enzymes, deficiency in which has been linked to hypertension, arthritis, anaemia, some cancers, and, even, possibly reduced sperm counts. So, clearly, it is a good idea to get some selenium inside you (it is found particularly in nuts, whole meal bread, and fish), but at the same time, if you take too much, you can irremediably poison your liver. As with much of life, getting the balances right is a delicate business.” End Quote.

The above lines are quoted from Bill Bryson’s book The Body: A Guide for Occupants. ISBN-13: 978-0385539302. I can recommend the book highly. Bryson writes an English that is a pleasure to read, and the book is full of facts and relationships. You may already know him from his earlier book about science and technology, The Short History of Almost Everything. read more

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

Regional, age, and sex differences in serum selenium status

Selenocysteine is the 21st amino acid. The trace element selenium plays its important biological roles in the body as a component of selenocysteine. Selenocysteine is found in at least 25 selenoproteins including selenoprotein P and the various glutathione peroxidases, thioredoxin reductases, and iodothyronine deiodinases.

The results of clinical studies give us an estimate of what an individual’s optimal serum or plasma selenium status is.

  •  Plasma selenium status below 100 micrograms per liter  – also expressed as 100 nanograms per milliliter – is generally regarded as sub-optimal plasma selenium status [Hurst 2010].
  • Plasma selenium status of at least 110 – 118 micrograms per liter is considered necessary for the optimal expression of selenoprotein P [Hurst 2010]. 
  • Letsiou et al [2014] set the lower limit for optimal selenoprotein P activity at 120 micrograms per liter or higher.
  • Plasma selenium status of 120 up to 170 micrograms per liter is considered necessary for reducing the risk of prostate cancer [Hurst 2012].
  • Studies show that there are sex and age differences in the absorption and distribution of selenium taken in from the diet and from supplements [Letsiou 2014; Galan 2005].

Note: The Mayo Medical Laboratories report serum concentrations of 70 to 150 micrograms per liter as the adult reference range for residents of the United States.  The mean population serum concentration is 98 micrograms per liter [Mayo], but, remember, depending on the range and standard deviation of the data, the mean can be very little useful. The important thing about the United States is that there is regional variation in selenium intakes and status. See below.

Selenium intake and selenium status

The primary sources of selenium are the diet and supplements. The human body does not synthesize selenium.  It is difficult to calculate accurately how much selenium an individual gets from food.  It can also be difficult to know precisely how much selenium an individual absorbs from a supplement because of the variation in the form and formulation of the selenium supplements on the market. read more

Selenium and statin medications and selenoproteins

Adequate synthesis of several selenoproteins – including the various glutathione peroxidases and thioredoxin reductases and Selenoprotein P – is important for the anti-oxidative defense of the cells. Professor Urban Alehagen and a group of Swedish researchers observed significantly reduced death from heart disease in a 10-year follow-up of healthy elderly study participants who were given four years of combined high-selenium yeast and Coenzyme Q10 supplementation.

In a recent article on the web-site q10facts.com, I have posted a summary of an article in which researchers discuss the various ways in which statin medications may increase patients’ risk of atherosclerosis and heart failure.  Yes, the Japanese and American researchers say, the statin medications do lower cholesterol levels [Okuyama].  

But, the guidelines for the use of statin medications need to be re-examined.  The researchers say: There has been a remarkable increase in the incidence of heart failure in the same period that statin medications have been used [Okuyama].

Furthermore, there are known mechanisms by which statin medications could be causing an increase in the incidence of atherosclerosis and heart failure. read more

Selenium supplementation in the Su.Vi.Max. study

Depicted above (A): apoptosis in normal cell division with a damaged cell (2) and programmed cell death (1). Depicted below (B): cancer cell division with uninhibited cell production and increasingly more dangerous cell mutations. Selenium supplementation can help normal healthy adults who have low selenium status with cancer chemo-prevention benefits, thyroid function benefits, and cognitive function benefits.

The Su.Vi.Max. study —  SUpplementation en VItamines et Minéraux AntioXydants — was a big randomized, double-blind, placebo-controlled study carried out with typical French efficiency.  Even though I have written the name of the study in French, there are so many English cognates that I am sure you can read the full name of the study.

The study was designed to test the health benefits of daily supplementation with a number of vitamins and minerals at nutritional dosages (roughly, one to three times the daily recommended dietary intakes) [Hercberg 1998]:

  • selenium, 100 micrograms
  • vitamin C, 120 mg
  • vitamin E, 30 mg
  • beta-carotene, 6 mg
  • zinc, 20 mg

In particular, the French researchers wanted to see the effect of the daily supplementation over a long period, approximately 7.5 years, from 1994 to 2002, on the prevention of cancer and cardiovascular disease, both of which have been linked to oxidative stress and oxidative damage and might, therefore, be affected by supplementation with antioxidants. read more

We must not waste selenium

Selenium exists only in scarce quantities. Adequate dietary and supplemental intakes are vital for human health.  We need to use it carefully, and we need to begin to stockpile it for the use of future generations.

Selenium is a trace element.  It exists only in rare quantities in the world.  It is produced primarily as a by-product of the process of mining copper.  It is not recyclable.  It is very unevenly distributed in the soils of the earth.

Consequently, the availability of selenium in grasses and grains and, at the next stage of the food chain, in animals, varies considerably from region to region in the world. The human dietary intakes of selenium vary accordingly around the world.

Selenium a vital nutrient for humans
Selenium is a necessary micronutrient that our bodies do not produce.  We get our selenium primarily from our diets.  Selenium is important for good immune system function, good thyroid function, good reproductive function, and good protection of our cells’ DNA. read more

Selenium helps to avoid pregnancy complications

Adequate intakes of selenium can help to reduce the risk of some of the more serious complications of pregnancy. Studies done with an organic high-selenium yeast supplement have yielded encouraging results.

Women who have first-trimester miscarriages or recurrent miscarriages have been found to have significantly lower selenium status than women who do not miscarry.  Professor Margaret Rayman points out that blood selenium concentrations are typically lower during pregnancy, in part because there is an expansion of the volume of blood.  However, increased inflammation – implicated in miscarriages – could also be a cause of reduced circulating selenium [Rayman 2012].

For this article, I have searched the Medline database for results from randomized controlled studies involving selenium supplementation of low selenium status pregnant women.  There have been a number of interesting results.

Selenium and oxidative stress in pregnant women
Dr. Tara and a team of researchers did a simultaneous assay of pro-oxidant burden and antioxidant capacity in a total of 166 first-time-pregnant women.  In their first trimester, the women were randomly assigned to an active treatment group receiving 100 micrograms of a yeast-based selenium preparation (n=83) or placebo (n=83) per day until delivery. read more

Selenium and HIV and opportunistic infections

Individuals infected by the human immunodeficiency virus (HIV) that causes acquired immunodeficiency syndrome (AIDS) commonly have low selenium status. Selenium supplementation can prevent or delay the decline of immune system function and can protect against opportunistic infections.

Selenium supplements – especially selenium supplements as a component of a multi-micronutrient cocktail – can help to delay the decline of the immune system and can reduce the risk of death in HIV-infected patients.  Most of the data that we have comes from randomized controlled studies carried out in African countries, but the results are relevant to the United States and Europe.  Moreover, the results from studies of HIV-infected patients speak to the issue of the anti-microbial protection and antioxidant protection that comes with adequate selenium status.

Selenium and HIV and CD4 counts
CD4 cells are white blood cells that are part of the immune system.  Specifically, the CD4 cells fight infections in the body.  The HIV virus kills CD4 cells.  When a person has fewer CD4 cells, he or she is at greater risk of contracting an infection. read more

Selenium and reduced risk of cancer

The results of Dr. Larry Clark’s Nutritional Prevention of Cancer trial showed the efficacy of selenium supplementation in reducing the risk of colon cancer, lung cancer, and prostate cancer. Now, a meta-analysis of 69 studies shows that higher selenium exposure is associated with reductions in the risk of breast cancer, lung cancer, and prostate cancer.

Authors of a recent meta-analysis of 69 studies of selenium exposure and cancer risk have concluded that high selenium exposure can reduce cancer risk, especially high selenium exposure that is reflected in high plasma or serum selenium status and/or in high toenail concentrations [Cai 2016].  Admittedly, higher selenium intakes (as compared to lower selenium intakes) can affect different forms of cancer differently.  We still need more research to sort out which forms and dosages of dietary and supplemental selenium are most effective at reducing cancer risk.  In this article, I want to summarize the findings of Dr. Xianlei Cai and colleagues.

What is a meta-analysis of selenium exposure and cancer risk?
A meta-analysis is a research method of combining the data from several selected research studies to reach conclusions that have greater statistical power.  In the present case, Cai et al selected 69 studies that met their inclusion criteria.  Each one of the 69 selected studies had the following characteristics: read more

Selenium and heart disease

A study of serum selenium levels and supplementation with a patented organic selenium yeast preparation shows an association between serum selenium concentrations and the rate of deaths from heart disease in healthy elderly study participants.

There have been two noteworthy discoveries from a recent randomized controlled trial conducted by Dr. Urban Alehagen of Linköping University (Sweden) and his colleagues.

Firstly, people with low concentrations of selenium in their blood were found to be at significantly higher risk of death from heart disease.

Secondly, a combination of a patented high selenium yeast supplement and a proven Coenzyme Q10 supplement taken daily for four years provided significant protection against heart disease in people with low serum selenium status.

The KiSel-10 study of cardiovascular mortality
The study enrolled 668 healthy elderly individuals aged 70-80 years.  The study was well-designed and well-executed.  One group of 219 randomly selected individuals received 200 micrograms of selenized yeast tablets and 200 milligrams of Coenzyme Q10 capsules daily for four years. A second randomly assigned group of 222 individuals received matching placebos.  The remaining group of 227 individuals received no treatment at all. read more