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.
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.
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].
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.
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.
Moderate selenium deficiency is associated with increased risk of chronic disease: cancer, heart disease, thyroid disorder. Conversely, a selenium supplement containing one hundred (100) micrograms of selenium daily could reduce the risk of serious, age-related diseases in persons with moderate selenium deficiency, according to the known researcher Bruce Ames’ so-called triage theory.
Researchers Joyce McCann and Bruce Ames from Children’s Hospital Oakland Research Institute (CHORI) have analyzed the data from hundreds of scientific articles. They conclude that some selenium-dependent proteins that are regarded as essential for the body’s survival in the period until humans reach reproductive age are much more resistant to selenium deficiency than are other non-essential selenoproteins.
What is the idea behind a new website called seleniumfacts.com?
For the most part, what we want to do with this website is to present clinical research results from published, peer-reviewed studies of the safety and efficacy of selenium supplements.
A cousin website to the website q10facts.com
We want to try to do the same thing with seleniumfacts.com that we have been doing with q10facts.com website.
We want to report the results of human studies that have been done as randomized controlled clinical trials. We want to present the following types of information about selenium supplementation studies and selenium status:
the study design
the sample size
the composition of the sample
the selenium form and dosage
the length of the study
the confounding factors in the study
the study results
the researchers’ interpretation of the results
Intervention studies about selenium supplementation
Basically, there are two types of human studies: observational studies and intervention studies. The big difference between observational studies and intervention studies is that the researchers control the use of the independent variable in intervention studies but do not do so in observational studies.