What is selenium?
Selenium is a vital trace element. As the term trace element suggests, our body requires only minor amounts of it. In most cases, the total amount of selenium in our body lies between 5 – 15 milligrams. Our daily requirement of selenium falls within the microgram range. At the same time, every individual cell requires selenium. For this purpose, selenium is built into selenium proteins that handle important functions in our body.
What is selenium deficiency?
A selenium deficiency occurs when we do not take in sufficient selenium on a regular basis. The recommended daily requirement of selenium may only be around 70 micrograms. Nevertheless, in many cases not enough selenium is absorbed with food [1] in what are often called selenium deficiency countries, which also includes Germany.
This insufficient selenium intake leads to a deficient supply which our body attempts to compensate for by redistributing the selenium. In case of a selenium deficiency, certain selenium proteins which are essential for our survival are preferentially supplied with selenium [2].
On the other hand, the activity of the remaining selenium proteins drops since there is no longer sufficient selenium available to them. However, these selenium proteins are essential for our health. This includes the most frequent selenium protein in our body, which is an important component of our defense against oxidative stress. Likewise, it also affects the selenium protein that activates our thyroid hormones.
The Federal Institute for Drugs and Medical Devices (Bundesamt für Arzneimittel und Medizinprodukte, BfArM) established the definition of a selenium deficiency for selenium drugs. Selenium values under 80 micrograms per liter of selenium in the blood or under 100 micrograms per liter of selenium in whole blood represent a selenium deficiency [3].
What are the symptoms of a selenium deficiency?
The symptoms of selenium deficiency are mostly unspecific, such as fatigue, hair loss, brittle nails, or muscular weakness. Other symptoms of a selenium deficiency only take effect in the longer term and increase the risk for certain illnesses [4, 5].
How can my selenium status be checked?
The selenium status can be determined through blood. Since only one third of the selenium is located in the liquid components of the blood and the remaining two thirds in the solid components, a measurement in whole blood is preferred for determining the long-term selenium status. Determining the selenium status is not part of routine blood tests. As a rule, the costs for selenium measurement are not covered by health insurance companies.
Talk to your doctor about whether the laboratory with which he or she is working, performs a determination of selenium in whole blood. The biosyn service laboratory offers selenium analyses in whole blood and serum. Link to the relevant site (Selenium deficiency test).
What is an optimal selenium status?
The optimal selenium status is the third important marker of selenium, next to the normal range and the selenium deficiency. The optimal selenium status is based on the selenium values that are associated with positive health results in clinical studies. For this reason, only selenium values at the upper end of the normal range should be assessed as optimal. In whole blood, the upper end of the normal range is at 140 microgram per liter and in serum at 120 microgram per liter [4, 6, 7].
What should I do in case of selenium deficiency, and will selenium medications be covered by health insurance?
If a selenium deficiency were to be shown in your blood, it should be corrected promptly. Depending on your selenium status, your attending physician will suggest a corresponding therapy.
For a demonstrated selenium deficiency that cannot be corrected with nutritional measures, there are selenium medicines with different dosages that require a prescription and can be prescribed by your physician.
In case of a demonstrated selenium deficiency, the costs for prescription selenium medicine will be covered by health insurance.
Which form of selenium should I take?
In Germany, only sodium selenite or sodium selenite pentahydrate is approved as an active ingredient in selenium medicine. In the case of sodium selenite pentahydrate, it is a clinically tested active ingredient that can effectively correct a selenium deficiency.
Why sodium selenite pentahydrate is so unique?
Sodium selenite pentahydrate – a long name for a small molecule. Centre stage is the sodium selenite which is surrounded by five water molecules. The water molecules increase the solubility so that sodium selenite pentahydrate can also be used in injection solutions.
Our body handles the different forms of selenium that occur in nature, such as sodium selenite, sodium selenate, selenomethionine or selenocysteine, in different ways [8]. For this reason, it is especially important to be careful which form of selenium is being taken.
Most often, the question of bioavailability is at the center. Bioavailability indicates the degree and speed with which an active ingredient enters the blood circulation.
However, a high bioavailability is not the key element in case of selenium since the human body cannot detect certain forms of selenium and/or has to exert a very great effort in order to integrate this form of selenium into the selenium metabolism. This applies, for example, to the amino acid-bound selenium selenomethionine [8].
Sodium selenite, on the other hand, is directly integrated in the selenium metabolism so that the same amount of selenomethionine could achieve only one third of the activity for selenium proteins compared to sodium selenite in a human cell model for the intestinal wall [9].
Sodium selenite, which our body does not need, is largely excreted via the kidneys by means of urination. It can even be exhaled via the lungs [8].
Therefore, sodium selenite is safe and targeted as a supplement if it is used at suitable dosages.
References:
- Hughes DJ et al. Int J Cancer. 2015 Mar 1; 136(5): 1149-61. Selenium status is associated with colorectal cancer risk in the European prospective investigation of cancer and nutrition cohort.
- Schomburg L, et al. Biochim Biophys Acta. 2009 Nov;1790(11):1453-62. Hierarchical regulation of selenoprotein expression and sex-specific effects of selenium.
- Fachinformation selenase 50 AP, biosyn Arzneimittel GmbH, Stand Juli 2021.
- Rayman MP. Lancet. 2012 Mar 31; 379(9822): 1256-68. Selenium and human health.
- Bundesgesundheitsblatt – Gesundheitsforschung – Gesundheitsschutz 2006.49: 88-102. Selen in der Umweltmedizin.
- Bleys J, et al. Arch Intern Med. 2008 Feb 25;168(4):404-10. Serum selenium levels and all-cause, cancer, and cardiovascular mortality among US adults.
- Hurst R et al. Am J Clin Nutr. 2010 Apr; 91(4): 923-31. Establishing optimal selenium status: results of a randomized, double-blind, placebo-controlled trial.
- Suzuki KT. J. Health Sci. 2005; 51: 107-114. Metabolomics of Selenium: Se Metabolites Based on Speciation Studies.
- Zeng H, et al. Biol Trace Elem Res. 2011 Nov; 143(2): 1209-1218. Chemical form of selenium affects its uptake, transport, and glutathione peroxidase activity in the human intestinal Caco-2 cell model.
