Why Selenium Increases Your Odds for Mild Infection

  • 6 May 2020
  • Reading time 4 mins
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For most people a COVID-19 infection is unpleasant but over in a week. For some it is severe and potentially fatal. Why the difference? Selenium and vitamin D levels – says two recently published studies.

The first, in China, finds a direct correlation between COVID-19 deaths and selenium levels.1 What you might not know about China is that there is a belt of land running through Hubei Province and Wunan where the soil level of selenium is really low and so is the food and the people, as determined by hair mineral samples. While there are other areas of China where it is really high. The same is true in Africa. The highest is in Senegal in West Africa, which has high soil selenium levels, since it is situated in the desiccated or dried up Cretaceous and early Eocene Sea, hence the soil was underwater. It has a low prevalence of AIDS at 0.7%.Whereas in sub-Saharan Africa, as well as South Africa, where selenium soil levels are lowest, the incidence is between 3% and 20%3. Is this a coincidence?

What is known about selenium deficiency is that, when an infected animal is deficient viruses can mutate to become more deadly, and go on to infect others. Your ability to fight off a virus also depends on your selenium level. Selenium protects you in three ways. Firstly, it helps your immune system to fight back and helps your immune cells and macrophages, which gobble up viruses, to work properly.4 Secondly, it helps to clean up oxidants which are produced by both the virally infected cells and your immune cells, which helps to reduce symptoms. Thirdly, and most interestingly, it slows down replication of the virus, and inhibits its mutation into new forms.

You don't need much selenium. While there’s good merit in taking a gram an hour of vitamin C, or 20 grams across 24 hours when under viral attack, 200mcg a day of selenium is more than enough. That’s 100,000 times less than the amount of vitamin C.

The other protective nutrient is vitamin D. It’s pretty obvious, with flu happening in the months from December to March when vitamin D levels are at their lowest, and with the highest risk group being the BAME population with darker skin, that all roads point to sunlight, and consequently vitamin D, as a main player is relation to risk.Countries close to the equator, such as Kenya, Uganda and Rwanda, have reported, collectively, only 24 deaths (as at May 5th).

But this moves even more centre stage with a recent study conducted by the US GrassrootsHealth.org ongoing survey.5 They had data on several hundred people who had contracted COVID-19 and split then into those for whom the infection was either mild, ordinary, severe or critical. They also had their vitamin D levels and split them into three categories: low meaning a deficient blood level below 50nmol/l; medium being between 50 and 75nmol/l; and above 75nmol/l as being sufficient. First, the good news – only 4 per cent of those having critical or severe infection had blood levels above 75 nmol/l, while 98 per cent having a mild infection had vitamin D blood levels above 75 nmol/l. Conversely, over half of those with severe or critical condition had a deficient vitamin D level below 50nmol/l.

So, just by upping your selenium and vitamin D level you can improve your odds of having a mild infection if infected. From other studies those taking 8 grams or more of vitamin C in the first day of an infection are symptom free within 24 hours. Zinc is also known to kill viruses within cells. High doses of zinc, above 50mg, together with 500mg of quercitin twice a day, which drives zinc into virally infected cells, may further speed up recovery. This is the equivalent of your internal PPE, perhaps just as important as social distancing and hand washing.

Please note: do not exceed 200mcg of selenium on a daily basis and even this is advisable only during an infection for a maximum of a couple of weeks. Otherwise,100mcg of selenium a day is enough. Vitamin D, on the other hand, can be taken in large amounts short term to get your blood level up to an optimal level of 100nmol/l. There is no harm in taking 50,000iu a day for five days to rapidly achieve this. Once achieved 1,000iu daily should suffice.


1. Jinsong Zhang, Ethan Will Taylor, Kate Bennett, Ramy Saad, Margaret P Rayman, Association between regional selenium status and reported outcome of COVID-19 cases in China, The American Journal of Clinical Nutrition, , nqaa095, https://doi.org/10.1093/ajcn/nqaa095

2. See ‘Selenium Conquers AIDS?’ https://www.i-sis.org.uk/AidsandSelenium.php

3. See https://en.wikipedia.org/wiki/HIV/AIDS_in_Africa#Regional_prevalence

4. J Avery and P Hoffmann, ‘Selenium, Selenoproteins, and Immunity.’ Nutrients, (2018), 10(9):1203. [https://www.mdpi.com/2072-6643/10/9/1203]

5. See https://www.grassrootshealth.net/blog/first-data-published-covid-19-severity-vitamin-d-levels/