Guest post: Selenium in the Body: Selenoproteins: By Jesse Davis, DC

From Dr. Charles:

Modern physiology research is showing Selenium to be a vitally important mineral to thyroid and immune function.

Yet most individuals are deficient in this critical mineral. More importantly though the FORM of selenium taken in supplemental form is critical to its uptake and utilization.

Today we feature Dr. Jesse Davis who has a must read blog for you.


Posted with permission

Selenium in the Body: Selenoproteins:

By Jesse Davis, DC

Selenium is a micronutrient that plays a key role in proper immune system functioning. The function of selenium in the body is largely brought about by its incorporation into a group of proteins known as selenoproteins. These proteins, of which there are 25 known, have selenium incorporated throughout their structure as a modified cysteine amino acid residue known as selenocysteine. [i]

The 2012 article titled “The Role of Selenium in Inflammation and Immunity: From Molecular Mechanisms to Therapeutic Opportunities” had further to say about the specifics:

“Selenoproteins are involved in the activation, proliferation, and differentiation of cells that drive innate and adaptive immune responses. Dietary Se and selenoproteins are not only important for initiating or enhancing immunity, but they are also involved in immunoregulation, which is crucial for preventing excessive responses that may lead to autoimmunity or chronic inflammation. “ [ii]

Selenium and Immune Function

broccoli, cabbageThe article described ways in which selenium is used and being investigated in ill patients with viral infections for its ability to support the immune response.

“Dietary supplementation to provide adequate or supranutritional selenium supply has been proposed to confer health benefits for patients suffering from some viral diseases, most notably with respect to HIV and influenza A virus (IAV) infections…”

It went on to say:

“Viral and bacterial infections are often associated with deficiencies in macronutrients and micronutrients, including the essential trace element selenium.”[iii]

Micronutrients Work Together

Furthermore, there is a synergistic effect of selenium and other micronutrients that support proper immune function.

“The vitamins A, B6, B12, C, D, E and folic acid and the trace elements iron, zinc, copper and selenium work in synergy to support the protective activities of the immune cells. Finally, all these micronutrients, with the exception of vitamin C and iron, are essential for antibody production. Overall, inadequate intake and status of these vitamins and trace elements may lead to suppressed immunity, which predisposes to infections.” [iv]

Selenium has been investigated for its role in asthma related airway inflammation[v], autoimmune hypothyroid conditions[vi] and also its actions as an antioxidant.

“As an antioxidant, selenium plays a vital role in minimizing free-radical activity and is known to strongly influence immune responses.”[vii]

Brazil nutsAs with many micronutrients, providing sufficient amounts to meet needs provides the best results, while excessive doses do not necessarily show benefits. The asthma study above used a mouse model to show a moderate supplemented diet improved airway inflammation markers, while both low and high selenium feed were not as useful in promoting the increase of selenoproteins involved.

In addition, the presence of sufficient selenium has had a correlation with decreased incidences of cancer. A 2015 paper in the journal Nutrients detailed where the line has been found to be impactful on risk:

“The Nutritional Prevention of Cancer Trial found supplemental Se to reduce cancer risk in non-deficient Americans only if their baseline plasma Se levels were less than ca. 120 ng/mL. This is consistent with the results of the larger Selenium and Vitamin E Cancer Prevention Trial (SELECT), which found no risk reduction in a cohort with baseline plasma Se concentrations exceeding that level.”[viii]

Selenium activity is thought to be well established by blood test. They went on to say “the most useful tissue for assessing Se status, particularly in humans, is plasma… Selenium is stable in plasma as long as microbial growth is prevented; it can be determined with very good sensitivity and precision. 9

Selenium Type Matters

Delivery of selenium as a supplement has been investigated in both inorganic and organic forms. Organic forms that have been used are often an inactive yeast-based method that has had selenium already incorporated into protein structures for better bio-availability.10

“Because of its non-specific incorporations into proteins, food sources of SeMet support greater tissue Se accumulation than comparable intakes of Se in inorganic forms. For this reason, animal studies using tissue Se accumulation as the measure of bioavailability typically show Se in foods/feedstuffs to be more highly available than selenite or selenate.” 11

shiitake mushroomsIn fact, the higher the level of biological incorporation of selenium, evidence shows the more functional impact it has. As mentioned, yeast-enriched methods of delivering selenium have the highest absorption rates. They also have a greater impact in vivo in numerous studies across a wide spectrum. Yeast cells are capable of effectively assimilating inorganic minerals such as selenium into their biological components.12

Yeast-based delivery methods have been shown to behave functionally different in the body compared to supplementing inorganic forms or even selenomethionine. Yeast-based selenium delivery showed a greater improvement in children with Kashin-Beck disease (a form of osteochondropathy affecting children) than sodium selenite.13 A recent RCT looking at oxidative stress markers and their potential endpoints found yeast-based selenium delivery superior to selenomethionine. From the published results in a 2014 issue of Cancer Prevention Research:14

  • “Epidemiologic and laboratory studies indicate that dietary selenium protects against prostate cancer. Results from clinical trials suggest that selenium-enriched yeast (SY) but not selenomethionine (SeMet) may be effective at reducing prostate cancer risk. Our objectives were to directly compare for the first time the effects of SeMet and SY on prostate cancer relevant biomarkers in men.”
  • “These decreases were greatest in individuals with low baseline plasma levels of selenium (<127 ng/mL).”
  • “ Overall, we showed for the first time, reductions in biomarkers of oxidative stress following supplementation with SY but not SeMet in healthy men.”

It is clear that optimal levels of selenium intake through food or supplemental means has a broad effect on human health and the immune system in particular. Since selenium is primarily incorporated into proteins in the body, the form of selenium matters in absorption and also subsequently in function. Knowledgeable activity on the part of the clinician should be based on the patient’s physiological status and nutritional intake to aid in achieving the best outcomes for the patient.


1 Papp LV, Holmgren A, Khanna KK. Selenium and selenoproteins in health and disease. Antioxid Redox Signal. 2010 Apr 1;12(7):793-5.

2 Huang Z, Rose AH, Hoffmann PR. The Role of Selenium in Inflammation and Immunity: From Molecular Mechanisms to Therapeutic Opportunities. Antioxidants & Redox Signaling. 2012;16(7):705-743.

3 Steinbrenner H, et al. Dietary selenium in adjuvant therapy of viral and bacterial infections. Adv Nutr. 2015 Jan 15;6(1):73-82.

4 Maggini S, et al. Selected vitamins and trace elements support immune function by strengthening epithelial barriers and cellular and humoral immune responses. Br J Nutr. 2007 Oct;98 Suppl 1:S29-35.

5 Hoffmann PR, et al. A role for dietary selenium and selenoproteins in allergic airway inflammation. J Immunol. 2007 Sep 1;179(5):3258-67.

6 van Zuuren EJ, et al. Selenium Supplementation for Hashimoto’s Thyroiditis: Summary of a Cochrane Systematic Review. Eur Thyroid J. 2014 Mar;3(1):25-31.

7 Vieira AT, Teixeira MM, Martins FS. The role of probiotics and prebiotics in inducing gut immunity. Front Immunol. 2013 Dec 12;4:445.

8 Combs GF. Biomarkers of Selenium Status. Nutrients. 2015;7(4):2209-2236. doi:10.3390/nu7042209.

9 Kieliszek M, Błażejak S, Gientka I, Bzducha-Wróbel A. Accumulation and metabolism of selenium by yeast cells. Applied Microbiology and Biotechnology. 2015;99(13):5373-5382. doi:10.1007/s00253-015-6650-x.

10 ibid, Kieliszek M, Applied Microbiology and Biotechnology.

11 ibid, Kieliszek M, Applied Microbiology and Biotechnology.

12 Kieliszek M, Błażejak S, Gientka I, Bzducha-Wróbel A. Accumulation and metabolism of selenium by yeast cells. Applied Microbiology and Biotechnology. 2015;99(13):5373-5382. doi:10.1007/s00253-015-6650-x.

13 ibid, Kieliszek M, Applied Microbiology and Biotechnology.

14 Richie JP Jr, et al. Comparative effects of two different forms of selenium on oxidative stress biomarkers in healthy men: a randomized clinical trial. Cancer Prev Res (Phila). 2014 Aug;7(8):796-804.

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