Selenium Compounds Fight Cancer

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The body’s selenium level can be measured by using a blood sample

In a new scientific study, Danish researchers from Copenhagen University have demonstrated that methylated selenium compounds can regulate the body’s immune system enabling it to better fight certain cancers. These selenium compounds are found in certain foods such as garlic and broccoli but also in the selenium preparations containing selenium yeast.

Certain cancers such as skin cancer, prostate cancer, and some forms of leukemia weaken the body’s immune system by overstimulating it until it eventually breaks down, giving cancer cells a free rein in the body. What this new Danish research shows is that the intake of selenium compounds that can be metabolized into methylselenol improves the immune system’s ability to fight cancer.

The immune activating substance NKG2D
The metabolism of various inorganic and organic-selenium compounds in the body is complex and closely regulated. The selenium compound methylselenol regulates the production of a substance called NKG2D. It is a substance that activates the body’s immune function and is seen in elevated quantities in cases of heat shock, viral infections, and inflammation; its presence is also elevated in the blood and on the surface of tumors in cancer patients.

This NKG2D substance is therefore also useful as a marker for serious illness. The selenium compounds that are converted to selenide in the body are not in a position to regulate the formation of NKG2D and are therefore less effective as anti-cancer agents than methylselenol is.

Selenium yeast formulation
This is where selenium yeast preparations enter the picture because they contain the methylated selenium compounds that have been found to be most effective in cancer treatment. Denmark, for example, has available a pharmaceutical version of selenium yeast that is the only preparation approved for the prevention and treatment of selenium deficiency and that may be prescribed at a dosage of 200 micrograms daily.

Selenium mechanisms
Selenium fights cancer primarily using two pathways: apoptosis and anti-angiogenesis. In the case of apoptosis (programmed cell death — as opposed to cell death by illness or injury), enzymes that cause cancer cells to die naturally are affected.

The second  pathway, anti-angiogenesis, is a process that inhibits the formation of new blood vessels to the cancer tumor. Without a supply of adequate nutrients through new blood vessels, the cancer cells will die more readily.

In fact, the effects of selenium supplementation on cancer enhances conventional chemotherapy.

Supplementation necessary
Other scientific studies involving selenium have shown that a daily supplement of 200 micrograms of selenium yeast has been able to reduce the number of cancer incidents and the number of deaths due to cancer.  The new Danish research suggests that the type of selenium used against cancer greatly affect the results.

It is noteworthy that the SELECT study from 2008, in which selenomethionine (which is a non-methylated selenium) was used for cancer patients, did not show a statistically significant effect against cancer. This negative result surprised many people, but the lack of a cancer preventive effect in he SELECT study has been attributed to several things, including the enrollment of patients who were not lacking selenium.

Based on the evidence of this new Danish research, the results could also be the explained by the fact that the patients were not supplemented using methylated selenium compounds.

Bottom line on selenium supplementation
The formulation of the supplement — organic selenium yeast formulation — is very important to the cancer preventing effect.  Another thing that is pointed out by the Danish researchers is that you can’t get the necessary amounts of selenium from the diet alone to fight cancer effectively.

The effectiveness of selenium supplementation in cancer prevention depends to an extent on the dosage needed to raise serum selenium status to a suitable level, but the effectiveness depends even more on the formulation of the selenium supplement.  To be effective in preventing and fighting cancer, selenium supplements must be comprised of the right chemical species of selenium.



Hagemann-Jensen M, et al. (2014). The Selenium Metabolite Methylselenol Regulates the Expression of Ligands That Trigger Immune Activation through the Lymphocyte Receptor NKG2D. J Biol Chem, 289(45):31576-90.

Weekley CM, et al. (2011). Uptake, distribution, and speciation of selenoamino acids by human cancer cells: X-ray absorption and fluorescence methods. Biochemistry, 50(10):1641-50.


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