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.
In my mind, I keep coming back to the question of heart health and the role that selenium supplements play in heart health. That may surprise many of you because we tend to think of selenium supplements primarily for the prevention of cancer and for the prevention of thyroid disorders and for protection against the toxic effects of heavy metals like mercury and cadmium. We know that our immune system needs adequate intakes of selenium if it is to function optimally. That’s correct, isn’t it?
Selenium supplements and good heart health
But, what about the relationship between selenium intakes and status and heart health? Writing in the medical journal, The Lancet, Professor Margaret P. Rayman, University of Surrey, in Guildford, United Kingdom, has listed and documented the following ways that adequate selenium status and optimal levels of selenoproteins can potentially benefit the heart [Rayman 2012]:
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.
The heart muscle tissue is frequently the first tissue in humans to suffer damage caused by selenium deficiency. When the cell membranes in the heart muscle tissue are damaged by the action of harmful free radicals (this is called oxidative damage), many of the healthy heart muscle cells are replaced by fibrous tissue. The resulting condition is called cardiomyopathy.
Cardiomyopathy is a disease of the heart muscle in which the heart is enlarged, thick, and rigid [Mayo Clinic]. As the cardiomyopathy worsens, the weakened heart muscle is less and less able to pump adequate quantities of blood to carry oxygen and nutrients to the cells and tissues throughout the body. Eventually, symptoms such as shortness of breath, early fatigue, and swelling in the legs and feet and abdomen appear, the symptoms of chronic heart failure.
Statin medications: good news and bad news? On the one hand, statin medications are effective at reducing cholesterol levels, and, are good, apparently, at reducing the number of deaths from heart attacks. On the other hand, we have seen a very considerable rise in the number of cases of chronic heart failure … in the same period that statin medications have been prescribed. Drs. Okuyama and Langsjoen and their colleagues have explained the pharmacological mechanisms by which this medical paradox may be occurring [Okuyama].
Statins inhibit the body’s production of Coenzyme Q10
Okay, I was aware of the evidence from well-designed studies linking the taking of statin medications to decreased plasma levels of Coenzyme Q10. Coenzyme Q10 is an important factor in cellular energy production and is an important lipid-soluble antioxidant [Folkers, Littarru, McMurray]. And I knew that the energy-deprived heart is a failing heart [Folkers, Molyneux, Mortensen]. So, I knew that anyone taking a statin medication needs to talk to his or her cardiologist about taking a good Coenzyme Q10 supplement.
How much selenium from food and supplements do we need on a daily basis? Which bio-markers of optimal selenium status seem to be most useful to answer this question? Dr. Rachel Hurst and Dr. Susan J. Fairweather-Tait, Norwich Medical School, United Kingdom, and their colleagues set out to find answers. The design of their study is very interesting.
They enrolled 119 healthy British men and women aged 50 – 64 years in a randomized, double-blind, placebo-controlled study that lasted 12 weeks [Hurst]. They excluded the following persons from the study:
people with already high plasma selenium status
people with long-term illnesses
people on various medications
people unwilling to discontinue taking vitamins and herbal remedies at least one month prior to the start of the study
selenium-enriched yeast tablets containing 50, 100, or 200 micrograms of a patented organic selenium (SelenoPrecise® preparation delivered by Pharma Nord, Denmark)
selenium-enriched onion meals that provided the equivalent of 50 micrograms of selenium per day
unenriched onion meals that provided the equivalent of less than 4 micrograms of selenium per day
Measurements of selenium
Remember: Selenium is a trace element. We measure its intake in micrograms per day, not milligrams. We measure selenium status in plasma and serum in terms of micrograms per liter (or equivalently, in nanograms per milliliter). Selenium in toenails or hair, then, we measure in micrograms per gram.
The trace element selenium is an essential component of the selenium-dependent enzymes called selenoproteins. We need these selenoproteins for the optimal biological functioning of our cells. Specifically, we need adequate daily intakes of selenium for the protection of cellular DNA, for successful reproduction, for proper thyroid gland function, for protection against infections, for anti-oxidative protection against the damage caused by free radicals, and for the prevention of cancer and heart disease.
What form of selenium is best?
Many of us cannot get enough selenium in our diets, especially if we do not regularly eat Brazil nuts (very high in selenium) or if we eat relatively little meat and fish. However, there are various supplemental forms of selenium available to us as consumers.
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.
Why the interest in selenium facts? Here, at the beginning of the seleniumfacts.com website, we want to review in broad terms what we know about the functions of selenium supplementation. We are especially interested in selenium’s antioxidant and anti-inflammatory effects in the human body.
Selenium is an essential trace element in the human diet, and, in many regions of the world, it is an absolutely necessary nutritional supplement. It has many and diverse functions in the human body.
One of the interesting things about selenium is that it does not perform its functions as an element or an ion. Instead, it functions as a component of more complex compounds. In particular, it is an essential component of the 21st amino acid, selenocysteine.