Selenium is a trace element essential for for DNA repair, for good immune function, and for reduced mortality risk.
The Micronutrient Information Center maintained by staff members at the Linus Pauling Institute of the Oregon State University provides reliable information about the vitamins and minerals and trace elements used in nutritional supplements.
Today, I want to summarize the information that the Center provides about selenium and supplement that information with the latest scientific research.
An Introduction to Selenium and Selenoproteins
Selenium is a trace element that is essential that humans need for the proper functioning of selenium-dependent selenoproteins. Free selenium is rare in the body. Instead, the selenium in the body is typically a component of selenomethionine, selenocysteine, and methyl-selenocysteine.read more
Sufficient selenium is required for the formation of the amino acid selenocysteine, which is, in turn, an essential component of selenoproteins.
Low selenium status over longer periods of time can put individuals at greater risk of cardiovascular disease, cancer, and autoimmune thyroid disorders.
Adequate selenium intake and status are necessary for good immune function and protection against infectious diseases.
Particularly vulnerable to have low selenium status are individuals who are vegetarians and vegans, pregnant and breastfeeding women, overweight or obese individuals, HIV-patients, kidney-dialysis patients, and individuals on parenteral nutrition as well as individuals living in selenium-poor regions.
Where is selenium status likely to be low?
Stoffaneller and Morse conducted a comprehensive study – 143 references – of selenium status in Europe, the UK, and the Middle East. They concluded that selenium intake and status are generally suboptimal in European and Middle Eastern countries, with somewhat more variation in the Middle East. They reported that suboptimal selenium status is widespread throughout Europe and the UK, with Eastern European countries having lower selenium intakes than Western European countries. In the Middle Eastern countries, they found varying results, which were possibly caused by different food habits and different imports in different regions and within differing socioeconomic groups [Stoffaneller & Morse].read more
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].
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
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?
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].
oxidative stress (= imbalance of harmful free radicals and protective antioxidants)
destruction of nerve cells (neurons)
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
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
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)
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
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 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
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
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
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