China and COVID-19 Virus: The Selenium Connection

Map of China
China has regions with selenium-rich soils and foodstuffs and regions with selenium-poor soils and foodstuffs. Researchers have compared the COVID-19 cure-rate and death-rate for infected individuals in selenium-rich and selenium-poor regions in China. They have found that regions with low selenium status have lower cure-rates and higher death-rates.

China and Corona Virus will be forever linked in our minds.  However, there is another important connection that we should be making: selenium status and its effect on COVID-19 virus in China.

Let me explain. Chinese and American and British researchers have published a letter in the American Journal of Clinical Nutrition in which they report evidence of a significant association between regional selenium status and the reported cure-rate of COVID-19 infected patients in China [Zhang 2020].

The researchers’ data show a statistically significant association between the reported cure-rates for COVID-19 virus infections and selenium status in China [Zhang 2020].

The Selenium Status and COVID-19 Cure-Rate

Beginning in mid-February 2020, the researchers collected data from the Baidu website, which they describe as a non-governmental website that provides daily updates of reports from the health commission of each province in China. read more

Selenium and Longevity and Ageing

There are notable regional variations in the blood selenium concentrations in senior citizens. The differences range from 66 micrograms per liter in Brazil and Turkey to 126 micrograms per liter in Japan.  Below 85 micrograms per liter is poor selenium status.  The desirable range is thought to be 125-135 micrograms per liter.

We want, all of us, to stay as young and healthy as possible as late in life as possible.  Ageing is inevitable.  How can we delay the onset of ageing’s bio-chemical and physiological consequences?

  • Physical exercise?
  • Caloric restriction?
  • Ingestion of micronutrients?

Selenium Status and the Health of Senior Citizens

The authors of a 2019 review article have found that, overall, there is an inverse correlation between age and blood selenium levels. Higher age is associated with lower blood selenium concentrations [Robberecht 2019].

Inadequate dietary intakes of selenium and poor selenium status (< 85 micrograms per liter in blood) may increase the risk of following harmful health outcomes [Robberecht]:

  • oxidative stress (= imbalance of harmful free radicals and protective antioxidants)
  • destruction of nerve cells (neurons)
  • dementia

Selenium Status and Biological and Social Factors

A variety of factors must be taken into consideration when we investigate the relationship between ageing and selenium intake and status.  There are, first of all, considerable regional variations in the availability of selenium in the soil and in foodstuffs [Stoffaneller & Morse]. read more

Normal Serum Selenium Levels

Dr. Margaret P. Rayman, Professor of Nutritional Science, University of Surrey at Guildford, said in 2002: ” Se deficiency is defined by Baum et al (1997)  as  a  plasma  level  ≤ 85μg/liter,  a  level  not  attained  in many northern European countries.”

Selenium is an important trace element that is needed for the proper functioning of our cells.  It is needed in very small amounts, but it might be a good idea to have a blood test done to check the serum selenium level.

The Mayo Clinic Laboratories state that the normal concentration in adult human blood serum is 70 to 150 micrograms per liter (the same as 70 to 150 nanograms per milliliter). According to the Mayo Clinic, the US population mean value is 98 micrograms per liter [Mayo Clinic].

Variations in Serum Selenium Levels

Diet, geographic location, demographic factors, and environmental factors all influence serum selenium levels.

The following factors are independent predictors of higher selenium status in the United States [Park]: read more

Selenium Intake and Status Related to Health

The quantity of selenium in foodstuffs may be inadequate in many parts of the world.  Sub-optimal selenium status is reported to be widespread throughout Europe, the UK, and the Middle East [Stoffaneller & Morse]. Coastal regions in the US tend to have selenium-poor soil. Vast regions in China, Korea, Siberia, Tibet, and New Zealand are low selenium regions. Low selenium status is associated with increased risk of cancer and cardiovascular disease and thyroid disorders [Tolonen].
The research evidence to date suggests that there is a U-shaped relationship between selenium intake and health.  According to a recent report by the long-time selenium researcher Professor Dr. Margaret P. Rayman, University of Surrey, UK, both selenium deficiency and selenium excess have been associated with adverse health effects.

Conditions Indicating a Need for Selenium Supplementation

Professor Rayman lists a number of conditions that have been associated in the research literature with selenium deficiency:

  • Keshan disease (a heart muscle disease caused by a selenium deficiency together with a strain of Coxsackie virus)
  • Kashin-Beck disease (a bone disease for which selenium deficiency is a factor)
  • Increased viral virulence
  • Increased mortality
  • Poorer immune function
  • Problematic fertility/reproduction
  • Thyroid autoimmune disease
  • Cognitive decline/dementia
  • Type-2 diabetes
  • Prostate cancer risk
  • Colo-rectal cancer risk (in women)
  • Increased risk of tuberculosis in HIV patients

Professor Rayman does not specify a plasma/serum selenium level for selenium deficiency

She does mention a US National Health and Nutrition Examination Survey that measured the serum selenium levels in 13,887 adult participants and then followed up for mortality for up to 18 years.  The mortality in that study showed a U-shaped association between serum selenium and death, with a serum selenium concentration of 135 micrograms per liter at the bottom of the U [Rayman 2019]. 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

Prostate cancer risk and selenium status

Selenium supplements in the form of organic high-selenium yeast tablets provide the best cancer chemo-protection. These supplements are made using the yeast species Saccharomyces cerevisiae in a selenium-enriched growth medium. The yeast cells that produce the high selenium yeast tablets are rendered inactive. They are killed off by a heating process. Strains of the same yeast species are used to brew beer and bake bread.

Selenium supplementation and the risk of prostate cancer?  What do we know?  We need to be careful in interpreting the research results that we have (and we need more research), but, yes, there is evidence for an inverse association between prostate cancer risk and selenium status [Hurst 2012].

As of this writing (April 2017), the protective effect of selenium supplementation against prostate cancer seems to be found in a relatively narrow range of plasma selenium status [Hurst 2012].  Furthermore, there seems to be a U-shaped relationship between selenium status and protection against prostate cancer.

If the concentrations of selenium in the plasma are too low, there is increased risk of prostate cancer.  This is a serious concern in many regions of the world. read more

A basic guide to selenium

Selenium is a by-product of the mining and refining of copper. There are no sites in the world for the mining of selenium alone. Given its relative scarcity and its many uses — industrial and agricultural as well as nutritional — selenium for supplements will surely be more expensive in the future, and there may well be shortages of it in the future. Accordingly, it is important for us to use it wisely and to conserve it.

Selenium is an important micronutrient.  It is essential for life for both people and animals.  The body cannot synthesize selenium and is dependent upon the selenium that it can get from food.  In many regions of the world, there is too little selenium in the soil and in the food, and supplementation is necessary for optimal health.

Regions with selenium-poor soil
In many regions of the world, the content of selenium in the soil is quite low.  In large parts of Asia, China in particular, and in much of Europe and the Middle East, there are low levels of selenium in the soil.

Plants accumulate inorganic selenium from the soil and convert it to organic selenium. In that way, the selenium enters the food chain. For example, cows eat grass containing selenium, and the some of the selenium enters the meat and the milk of the cows.  People eat the meat and drink the milk.  Too little selenium in the soil means too little selenium in the food. read more

Our bodies cannot make selenium for us

Cancer studies
The research base for supplementation with selenium shows the need for adequate daily selenium intakes and adequate selenium status. The formulation and the dosage of the selenium supplement are very important.

Daily selenium intakes?  We need to get this essential trace element – selenium — in our diets and in our supplements because our bodies cannot make it for us. The work of Dr. Gerhard N. Schrauzer, Dr. Raymond J. Shamberger, and Dr. Douglas V. Frost has shown that there is an inverse relationship between our selenium status and the risk of cancer mortality.  Animal studies show an inverse correlation between selenium status and incidence of cancer.  Observational studies show lower risk of various types of cancer with higher selenium status.

Intervention studies of selenium supplementation and cancer
Clinical studies in China
Large interventional studies in China, a region of the world with selenium-poor soils and foodstuffs, have shown that selenium supplements protect against hepatitis B virus and primary liver cancer [Yu] and that supplementation with a combination of selenium and other antioxidants reduces cancer incidence and mortality in a region characterized by high cancer mortality rates [Blot]. read more

How we know that selenium supplementation is important

Selen supplementation, virus
Adequate intakes of selenium are needed to ensure the optimal functioning of the selenoproteins in the body. Selenoproteins provide protection against the development of cancer and heart disease; they are important for immune system defense; they protect against damage caused by heavy metals and chemical toxins and radiation. And, there is evidence that some of the selenoproteins have anti-viral properties.

Selenium?  A trace element?  You might well ask: How do we know that adequate amounts of dietary and supplemental selenium are important to us?
The first answer is: because we can see that selenium deficiency makes people sick.
A further answer is that we now know that selenium is an essential component of antioxidant enzymes.
And, on the basis of the results of randomized controlled trials, we know that selenium supplementation reduces the risk of cancer, reduces the risk of heart disease, and improves immune function.
Selenium is also very useful for reducing the toxic effects of heavy metals in the body.

Reason number one: Selenium-deficiency diseases
Keshan disease
In the 1960’s and 1970’s, thousands of people living in a region of China with selenium-poor soil, and, consequently, with selenium-poor food, died from the effects of a form of heart disease.  The disease, which took its name from Keshan county in the afflicted region of China, is characterized by inflammation and enlargement of the heart muscle and excess fluid in the lungs. The primary cause of the disease was selenium deficiency. read more

Professor Jørgen Clausen: early selenium researcher

professor J. Clausen
Professor Jørgen Clausen was one of the first researchers to realize the importance of supplementation with selenium in regions of the world with selenium-poor soil.

Professor Jørgen Clausen, long-time professor in the Institute for Life Sciences and Chemistry, Roskilde University Center, in Roskilde, Denmark, was one of the early researchers to do clinical studies of the effects of supplementation with selenium. As such, it seems instructive to go back and look at the research done by Dr. Clausen and his colleagues at the end of the 20th century.

Professor Clausen’s selenium studies
Basically, Professor Clausen’s research can be described in five different categories:

  • Effect of selenium supplementation on the health of the elderly nursing home residents
  • Effect of selenium supplementation on the health of cigarette smokers
  • Effect of selenium supplementation on the health of patients with chronic neurologic disorders
  • Effect of selenium supplementation on the toxic effects of lead poisoning
  • Effect of selenium supplementation on the activity levels of the selenium-dependent antioxidant enzyme glutathione peroxidase

In addition, Professor Clausen was an early leader in the investigation of the absorption and health effects of various forms of inorganic and organic selenium supplements.

Selenium supplementation and smokers and oxidative stress
To understand Dr. Clausen’s interest in the effect of selenium supplementation on smokers, we must first understand the concept of oxidative stress and the related concept of oxidative damage.  Oxidative stress occurs when, in the process of metabolism of oxygen, the body produces, as a by-product, various reactive oxygen species (for example: peroxide, superoxide, hydroxyl, and singlet oxygen radicals) to excess. read more