Selenium_ An Essential Trace-element

By: Pallavi Vathiar. Practicing Clinical Nutritionist, Mumbai.

Email: fihealthie@gmail.com

Dietary selenium (Se) is an essential micro-nutrient that affects various aspects of human health, including optimal immune responses.

Why should we have robust Immunity?

When your immune system is in tip-top condition, you probably do not even notice it working away to protect you around the clock.

As immunity and the immune system are an overly complex collection of processes that act together to protect organisms against attacks by pathogens and malignancy. You will know when there is something wrong as your immune system is your body’s in-built defence system against illness and infection. If you feel good today, thank your immune system.

How Selenium comes into the picture when we talk about Immunity?

The public perception of selenium has changed significantly over the last decades. Originally known for its high toxicity, it was later recognized as an essential trace element and is now almost being marketed as a lifestyle drug.

Through selenium’s incorporation into selenoproteins, Se is involved in regulating oxidative stress, redox, and other crucial cellular processes in nearly all tissues and cell types, including those involved in innate and adaptive immune responses (1-3).

Few studies on Selenium

Recent studies have highlighted the benefits of milk enriched with Se as a unique source of Se that is more bioavailable and bioactive, compared with inorganic forms such as sodium selenite, or organic forms such as Se‐enriched yeast.(4,5) In addition, milk is also a rich source of macro‐ and micronutrients with immunomodulatory and antibacterial and antiviral properties (6). As a result, there is increasing interest in the use of dairy as a source of Se in human diets

Data from studies in humans suggest that Selenium supplementation enhance immunity, including both humoral and cell-mediated responses (7).

Another study shows that Selenium-supplemented subjects also showed more rapid clearance of the poliovirus, and the poliovirus reverse transcriptase–polymerase chain reaction (8).

Selenium Deficiency

Selenium deficiency produces biochemical changes that might predispose people who experience additional stresses to develop certain illnesses.

Selenium deficiency could exacerbate iodine deficiency, potentially increasing the risk of cretinism in infants (9,10).

Groups at Risk of Selenium Inadequacy

Selenium deficiency is exceedingly rare but selenium deficiency in isolation rarely causes overt illness the following groups are among those most likely to have inadequate intakes of selenium.

  • People living in selenium-deficient regions
  • People undergoing kidney dialysis
  • People living with HIV
  • People with Cancer
  • Facing Cardiovascular disease
  • Suffering from Cognitive decline
  • People with Thyroid disease

How much selenium do I need?

While too little selenium can cause serious health problems, too much can also be toxic.

According to ICMR (Indian Council of Medical Research), the nutrient requirements and Recommended Dietary allowance for Indians is 40 micrograms of Selenium per day.

Are Sodium Selenate and Selenium different?

Sodium Selenate is the sodium salt of selenium. As a trace mineral that is toxic in high doses, selenium is a cofactor for glutathione peroxidase, an antioxidant enzyme that neutralizes hydrogen peroxide.

Selenium may be chemoprotective for certain cancers, particularly prostate cancer. High dietary supplementation with sodium Selenate may inhibit the progression of hormone-refractory prostate cancer due, in part, to an antiangiogenetic effect (10).

Its molecular formula is Na2SeO4.

From where Do I get selenium?

It is easy to get enough selenium by making healthy choices.

Choosing a variety of antioxidant-rich vegetables and fruit, whole grains, lean meat and dairy, fish, legumes, nuts, and seeds will meet your selenium needs.

Sources of Selenium:

ChickenBrazil Nuts
FishSunflower seeds
Enriched foodsMushrooms
BeefOatmeal
PorkSpinach
TurkeyMilk and Yogurt
EggsLentils
Cottage CheeseCashews
Brown riceBananas

Reference:

  1. Behne D, Wolters W. Distribution of selenium and glutathione peroxidase in the rat. J Nutr. 1983;113:456-461.  https://pubmed.ncbi.nlm.nih.gov/6822915/
  2. Bainbridge DR. Use of (75Se)L-Selenomethionine as a label for lymphoid cells. Immunology. 1976;30:135–144.  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1444971/
  3. Gromer S, Eubel JK, Lee BL, Jacob J. Human selenoproteins at a glance. Cell Mol Life Sci. 2005;62:2414–2437. https://pubmed.ncbi.nlm.nih.gov/16231092/
  4. Uglietta R, Doyle PT, Walker GP et al. Tatura‐Bio® Se increases plasma and muscle selenium, plasma glutathione peroxidase and expression of selenoprotein P in the colon of artificially‐reared neonatal pigs. Asia Pac J Clin Nut 2007; 16 (Suppl. 3): S51. onlinelibrary.wiley.com/doi/full/10.1111/j.1747-0080.2008.00259.x
  5. McIntosh GH, Royle PJ. Supplementation of cows with organic selenium and the identification of selenium‐rich protein fractions in milk. In: TP Lyons, KA Jacques, eds. ‘Nutritional Biotechnology in the Feed and Food Industries’. Proceedings of Alltech 18th Annual Symposium. Cambridge, UK; Woodhead Publishing Ltd. 2002; 233– 8. https://en.engormix.com/dairy-cattle/articles/supplementation-cows-organic-selenium-t33534.htm
  6. Iran J Pharm Res. 2016 Summer; 15(3): 573–591. PMCID: PMC5149046PMID: 27980594. Health-Related Aspects of Milk Proteins. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5149046/
  7. Hawkes WC, Kelley DS, Taylor PC. The effects of dietary selenium on the immune system in healthy men. Biol Trace Elem Res. 2001;81:189–213. https://pubmed.ncbi.nlm.nih.gov/11575678/
  8. Broome CS, McArdle F, Kyle JA, Andrews F, et al. An increase in selenium intake improves immune function and poliovirus handling in adults with marginal selenium status. Am J Clin Nutr. 2004;80:154–162. https://academic.oup.com/ajcn/article/80/1/154/4690273
  9. Sunde RA. Selenium. In: Bowman B, Russell R, eds. Present Knowledge in Nutrition. 9th ed. Washington, DC: International Life Sciences Institute; 2006:480-97. https://ods.od.nih.gov/factsheets/Selenium-HealthProfessional%20/
  10. https://pubchem.ncbi.nlm.nih.gov/compound/Sodium-selenate#section=Molecular-Formula

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