COVID-19 and Vitamin D: Here's What You Need to Know (Updated Nov 2020)

Can vitamin D help against COVID-19? In recent weeks and months, several publications and studies have suggested that maintaining adequate levels of vitamin D would seem potentially beneficial in fighting the COVID-19 infection. This article explains what you need to know about vitamin D and COVID-19.

vitamin D

What Is Vitamin D?

Vitamin D is a fat-soluble vitamin, meaning that it dissolves in fats and oils and can be stored in your body for a long time.

Two main dietary forms exist (Trusted Source):
  • Vitamin D3 (cholecalciferol). Found in some animal foods, like fatty fish and egg yolks.
  • Vitamin D2 (ergocalciferol). Found in some plants, mushrooms, and yeasts.
Of the two, D3 (cholecalciferol) seems to be almost twice as effective at increasing blood levels of vitamin D as D2 (ergocalciferol) (Trusted Source, Trusted Source).

Vitamin D Deficiency Increases Your Risk for COVID-19 (Prevention)

To avoid confusion, do take note that there are various studies on vitamin D and COVID-19. Some studies focus on primary prevention meaning whether having sufficient vitamin D in your body will 'prevent' you from getting COVID-19 in the first place. The other type of studies focus on secondary prevention i.e. how vitamin D can prevent those who have already been infected to not succumb to a more severe disease (e.g. cytokine storm, acute respiratory distress (ARDS) or a fatal outcome.

A recent study, published in JAMA (JAMA Netw Open. 2020) found that persons who are likely to have deficient vitamin D levels at the time of COVID-19 testing were at substantially higher risk of testing positive for COVID-19 than were persons who were likely to have sufficient levels.

The same team above, has also published a preprint article: A study at the University of Chicago of over 4,000 patients that found that untreated vitamin D deficiency was associated with an increased risk for COVID-19 infection.

The epidemiology of COVID-19 provides evidence that vitamin D might be helpful in reducing risk associated with COVID-19 deaths. A May 6, 2020, report published in Aging Clinical and Experimental Research (its prepublication featured in the Daily Mail) found that countries with lower vitamin D levels also have higher mortality rates from COVID-19.

Another May 6, 2020 report (Nutrients. 2020) in the journal Nutrients pointed out that vitamin D concentrations are lower in patients with positive PCR (polymerase chain reaction) tests for SARS-CoV-2. As noted in this report, which retrospectively investigated the vitamin D levels obtained from a cohort of patients in Switzerland.

In a May 18, 2020, letter to the Federal Chancellor of Germany, Angela Merkel; Bernd Glauner and Lorenz Borsche highlight these and other studies and ask whether a nationwide supply of vitamin D has been considered in Germany.

Vitamin D and COVID-19 (Treatment): The Evidence

A study published in November 2020 from Singapore (CW Tan, Nutrition 2020), found that those who were started on a daily oral dose of vitamin D3 (1,000 IU), magnesium (150 mg) and vitamin B12 (500 mcg) within the first day of hospitalisation and continued up to 14 days were significantly less likely to require oxygen therapy and further intensive care.

A randomised study conducted in Spain has shown that high doses of calcifediol, the activated form of vitamin D can significantly reduce the risk of ICU treatment of COVID-19 patients.

“Our pilot study demonstrated that administration of a high dose of calcifediol or 25-hydroxyvitamin D, the main metabolite of vitamin D endocrine system, significantly reduced the need for ICU treatment of patients requiring hospitalisation due to proven Covid-19,” said Marta Entrenas Castillo of ReinaSofĂ­a University Hospital in Cordoba, the lead author of the study report.

Another publication (Aug 2020) from the International Journal of Infectious Diseases, highlighted that the majority of the Western population is deficient in Vitamin D. According to the author:

Vitamin D3 supplementation also requires additional vitamin K2 intake.
• The immunoregulating function of vitamin D is promising and might decrease the global epidemic mortality.
Causal loop diagram of the impact of vitamin D3 on the immune system

According to an editorial review (Aliment Pharmacol Ther. 2020) published in June 2020 by Irish researchers, people with vitamin D deficiency appear to be far more prone to severe COVID-19 infections.

Another observational study involving 212 patients in Southeast Asia found that of those with a critical or severe case of COVID-19, only 4% had normal levels, while 96% of those with a mild case of COVID-19 had normal vitamin D levels.

Mark Alipio with GrassrootsHealth conducted a retrospective multicenter study involving 212 patients in Southeast Asia who had COVID-19. He too found a strong correlation between vitamin D levels and disease severity. Those with the mildest disease had the highest vitamin D levels, and vice versa.

Another study, published in the Irish Medical Journal (May 2020) showed that the calculated COVID-19 mortality rate from 12 European countries shows a significant (P = .046) inverse correlation with the mean 25(OH)D plasma concentration.

The Irish Longitudinal Study on Ageing (TILDA) published in April 2020, suggested that vitamin D deficiency could have serious implications for COVID-19. Results from the Irish Longitudinal Study on Ageing (TILDA), showed that vitamin D plays a critical role in preventing respiratory infections, reducing antibiotic use, and boosting the immune system response to infections.

Another study, published in the journal Nutrients (April 2, 2020), carries the telling title, "Evidence That Vitamin D Supplementation Could Reduce Risk of Influenza and COVID-19 Infections and Death."

Mark Alipio with GrassrootsHealth conducted a retrospective multicenter study involving 212 patients in Southeast Asia who had COVID-19. He too found a strong correlation between vitamin D levels and disease severity. Those with the mildest disease had the highest vitamin D levels, and vice versa.

A preprinted study published in May 2020, looked at Vitamin D levels and inflammatory markers in hospitalized COVID-19 patients in Germany, South Korea (S. Korea), China (Hubei), Switzerland, Iran, UK, US, France, Spain, Italy (Daneshkhah, MedRxiv 2020). Patients with the lowest Vitamin D levels were about 15% more likely to get severe COVID-19 and cytokine storm. Vitamin D3 plays a role in inhibiting the cytokine storm that causes viral infections to become lethal.

Although there are currently no large randomised controlled studies demonstrating vitamin D’s effectiveness in COVID-19, there are many such studies underway. As of November 2020 there were over 35 studies in progress on the use of vitamin D in COVID-19. By the end of 2020 we should have some of the results of these trials.

How Much Should You Take?

The only way to know if you are deficient — and thus need to supplement — is by having your blood levels measured.

Your healthcare provider will measure the storage form of vitamin D, which is known as calcifediol. Anything under 12 ng/ml is considered deficient, and anything above 20 ng/ml is considered adequate.

The RDI for vitamin D is as follows (nih.gov):
  • 400 IU (10 mcg): infants, 0–12 months
  • 600 IU (15 mcg): children and adults, 1–70 years old
  • 800 IU (20 mcg): older adults and pregnant or breastfeeding women
Although adequacy is measured at 20 ng/ml, many health experts believe that people should aim for blood levels higher than 30 ng/ml for optimal health and disease prevention (Trusted Source).

Additionally, many believe that the recommended intake is far too low and that people need much more to reach optimal blood levels (Trusted Source).

According to the U.S. National Academy of Medicine, the safe upper limit is 4,000 IU (100 mcg) per day (nih.gov).

Optimize Your Other Nutrients

It's important to keep in mind that nutrients usually don't work in isolation. Many of them depend on one another, and increased intake of one nutrient may increase your need for another.

Some researchers claim that fat-soluble vitamins work together and that it’s crucial to optimize your vitamin A and K intake while supplementing with vitamin D3 (Trusted Source, Trusted Source).

This is especially important for vitamin K2, another fat-soluble vitamin that most people don't get enough of (nih.gov). One can also take 150 to 200 mcg of vitamin K2 per day, as it works synergistically with vitamin D. The only concern is that if you are on Coumadin (anticoagulant), you have to discuss vitamin K2 with your doctor as it will interfere with Coumadin.

Magnesium — another important mineral often lacking in the modern diet — may also be important for vitamin D function (Trusted Source). This is because magnesium helps to activate vitamin D, as the enzymes that metabolize vitamin D in the liver and kidneys require magnesium. In fact, about  half of those taking vitamin D supplements are unable to normalize their vitamin D levels until they take magnesium (BMC Med. 2013).

What Happens if You Take Too Much?

Vitamin D toxicity is extremely rare, but does occur with extreme doses. It is almost impossible to get too much vitamin D from sunlight or food.

Vitamin D toxicity usually develops over time, since extra vitamin D can build up in the body.

Nearly all vitamin D overdoses result from taking high amounts of vitamin D supplements.

The main symptoms of toxicity include confusion, lack of concentration, drowsiness, depression, vomiting, abdominal pain, constipation, and high blood pressure (Trusted Source).

A recent case report (BMC Geriatrics. 2020): a Brazilian retired 64-year-old female, presented to the emergency service with vomiting, abdominal pain, frontal headache, fatigue, weight loss of 18  kg, severe itchiness, musculoskeletal pain in the limbs and high blood pressure. Due to the rarity of vitamin D toxicity, the definitive diagnosis was prolonged. The diagnosis was confirmed with a Vitamin D blood test. Lab results also showed high level of blood calcium (hypercalcemia) and acute kidney injury.

Wrap-up

Do we have large randomised controlled trials to prove that vitamin D can combat COVID-19. Not at the moment.

Of course, the most important thing you can do to avoid infection with coronavirus is to prevent exposure by following the latest recommendations of the CDC and World Health Organization such as wearing face mask, social distancing and hand sanitisation. Also take steps to stay healthy, including getting adequate sleep and exercise and eating a healthful diet that includes adequate (but not excessive) intakes of essential nutrients, such as vitamins C and D.

For those with hypertension, please take steps to control your blood pressure as high blood pressure is associated with more severe outcome if infected.

Your own immune system, works best when fed right. As long as you are taking supplements under medical supervision and within a safe range, the risk is low but the potential benefit is high. What have you got to lose?

Sources: 

Buy Vitamin D supplement in Malaysia: Vitamin D3 supplements appear to be more effective at raising vitamin D levels than D2 supplements. One can also take vitamin K2 together with D3 as vitamin K2 works synergistically with vitamin D3. D3 capsules are available in most supermarkets and health food stores such as Guardian and Watsons, as well as online.

Do take note that you can also get good amounts of vitamins C and D, zinc, and other essential vitamins and minerals from a basic multivitamin.

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