Selenium is a vital trace element nutrient with multiple roles in the growth and functioning of living cells of higher animals and humans. This element is unevenly distributed in the earth’s crust
Almost all of the selenium in animal tissue is found in the proteins. Some of these proteins contain stoichiometric quantities of selenium and are known as selenoproteins. Similarly, other proteins contain variable amounts of selenium (which substitutes sulfur randomly in the original protein) and are known as selenium-binding proteins
At the molecular level, selenium (as selenocysteine) is an essential component of the active sites of antioxidant enzyme glutathionine peroxidase, and the enzymes participating in thyroid functions – iodothyronine 5-deiodinase and mammalian thioredoxin reductase. Selenium is also present in several other mammalian selenoproteins. Lastly, selenium occurs in foods in the form of the seleno-amino acids (selenomethionine and selenocysteine) and their derivatives
Both glutathione peroxidase and thioredoxin reductase catalyze reactions essential to the protection of cellular components against oxidative and free radical damage
“Recent laboratory experiments, clinical trials, and epidemiological studies have highlighted the importance of selenium in supporting overall health and wellness. Selenium’s role is particularly noted in its contribution to the body’s antioxidant systems, which are crucial for maintaining cellular health and vitality. These findings underline the potential of selenium in supporting the body’s natural defense mechanisms against oxidative stress, which is a common factor in the natural aging process and general well-being. Selenium’s involvement in various enzyme systems underscores its importance in maintaining health and supporting the body’s normal functions.”
Background
Berzelius, a Swedish chemistry professor, discovered selenium in 1817. The mineral is present in the earth’s crust and is chiefly derived as a by-product of the copper refinery. Depending on soil composition, selenium is most abundant in foods such as meats, fish and grains
Benefits
For over four decades, selenium has been acknowledged as an essential nutrient for human health. The foundational work by Schwartz and Foltz in 1957 identified selenium as a crucial trace element, highlighting its significance in nutrition. Their research contributed to understanding selenium’s vital role in supporting the body’s overall well-being and maintaining normal physiological functions
Low dietary levels of selenium in animals and humans have been linked to several disease symptoms. In animals, selenium deficiency has been associated with muscular dystrophy in sheep calves, liver necrosis in rats, liver and heart necrosis in pigs, and pancreatic atrophy and exudative diathesis in chicks. Human selenium deficiency has been documented in the pathogenesis and pathology of Keshan disease; a heart ailment observed in people of the Chinese province of Keshan, a region whose soil lacks adequate selenium levels. Myositis (muscle diseases characterized by inflammation and degenerative changes), psuedoalbinism, whitening of the fingernail beds, elevated creatinine kinase derived from muscles, macrocytosis (the presence of abnormally large red cells in the blood), osteathropathy (Kashi-Beck disease), and an increased incidence of cardiovascular disease and cancer in humans are also associated with low selenium levels
Organic vs Inorganic
Plants absorb selenium from the soil and convert them into organic forms that are easily assimilated. For example, L-(+)- selenomethionine, and organic compound, is the predominant form of selenium in wheat and cereals. L-(+)- selenomethionine is rapidly and completely absorbed from the gastrointestinal tract
Inorganic forms of selenium include sodium selenite and sodium selenate; they are not normal food forms of selenium. In comparing L-(+)- selenomethionine (LSM) with its inorganic counterparts the following was determined
LSM is significantly better absorbed and retained in the body than sodium selenite
In experimental animals supplemented with LSM, sodium selenite and selenocysteine, the highest increase in tissue selenium levels was accomplished with LSM. In addition, studies have suggested that LSM has a slower, whole-body turnover in comparison to sodium selenite. This means there is greater efficiency in the utilization of selenium in complex with methionine. Due to the role of methionine in aiding the safe metabolism of selenium, LSM is recognized as safer from of selenium than sodium selenite
Research
A significant amount of research is published annually on selenium, highlighting its potential role in supporting various aspects of health. Studies have investigated its impact on supporting the body’s defenses, immune system, joint health, and cardiovascular wellness. Among these, the work by Clark et al. stands out for its exploration of selenium’s role in human health over a ten-year period. While the study found that selenium supplementation had an interesting association with certain health outcomes, it’s important to note that these findings have encouraged further research to understand selenium’s role in supporting overall well-being. Specifically, although the study observed a reduction in the incidences of certain types of health concerns in the selenium-supplemented groups, these observations have led to discussions and the potential for more focused follow-up studies to explore selenium’s health-supporting potential more thoroughly
One follow-up study, funded by the National Cancer Institute (NCI) and coordinated by the Southwest Oncology Group (SWOG), is known as SELECT (Selenium and vitamin E Cancer Prevention Trial). It is a 12-year, prostate cancer study conducted with 32,000 men from the United States, Canada, and Puerto Rico. The IND number for this study is #58,212. The exclusive form of selenium chosen and used by NCI for this study is Sabinsa’s Selenium SeLECT®. Sabinsa is contracted to supply capsules of Selenium SeLECT® as well as the placebo for the trial
Selenium SeLECT®, a registered trademark of Sabinsa Corporation, is supplied in two grades as an organic, bioavailable, fully complexed (not a dry blend of selenium and methionine) form of selenium. Selenium SeLECT® Pure contains a minimum of 400,000 μg of elemental selenium (40%) per gram, and Selenium SeLECT® 5000 (a dicalcium phosphate trituration), containing a minimum 5,000 μg of elemental selenium (0.5%) per gram. Both grades are yeast and allergen-free and conform to USP monograph standards
