Vitamin D3 proven to reduce the infection and impact of COVID-19, multiple scientists confirm

Discover the best supplements and dosage to top up your Vitamin D3 levels and protect against respiratory conditions.

Last updated: 9 November 2020

Vitamin D3 is proving to be a worthy contender in the fight against COVID-19. As scientific studies continue to mount, it’s becoming increasingly clear that Vitamin D supplements are a valid way to reduce your risk of catching COVID-19, hospitalization, severe complications and even death from the virus1.

Here are just some of the study findings that prove the importance of Vitamin D supplementation amid the pandemic.

  • A recent study of COVID-19 patients found that those who were vitamin D sufficient had significantly lower risk of adverse clinical outcomes, lower blood levels of the inflammatory marker C-reactive protein, and higher blood lymphocyte levels that allow for better immune responses. Patients with sufficient Vitamin D levels also had a lower risk of death: 9.7% of patients older than 40 years who were Vitamin D sufficient succumbed to COVID-19 compared to 20% who were Vitamin D deficient. The researchers concluded: “Therefore, it is recommended that improving vitamin D status in the general population and in particular hospitalized patients has a potential benefit in reducing the severity of morbidities and mortality associated with acquiring COVID-19”2.
  • In this same study of 191,779 patients across 50 U.S states, people with sufficient vitamin D levels had an approximately 54% reduced risk of catching COVID-193.
  • In a study of 7,807 Israelis, those lacking sufficient levels of Vitamin D had a 58% increased risk of COVID-19 infection, and were over two times more likely to be hospitalised as well4.
  • In a pilot study of 76 Spanish patients hospitalised with COVID-19 infection, a randomized group of 50 patients were given approximately 30,000IU of Vitamin D in the first week of their hospital admission – along with the other medications given for standard care. Only 2% needed to be admitted to ICU and none of the patients died. In the group of 26 patients that were not given Vitamin D, 50% required admission to ICU and two patients died5.
  • In a retrospective study of patients tested for COVID-19, researchers at the University of Chicago Medicine looked at 489 patients whose Vitamin D level had been measured within a year before being tested for COVID-19. Patients who were Vitamin D deficient that were not treated were almost twice as likely to test positive for COVID-19 compared to patients who had sufficient levels of the vitamin6.

The best Vitamin D3 supplements and the recommended dosage

Most people are Vitamin D-deficient and require supplementation to achieve optimal levels. (Click here to find out more about Hong Kongers and Vitamin D-deficiency and how to know if you’re lacking this vital vitamin).

Before you reach for an off-the-shelf supplement, remember: not all supplements are created equal. Vitamin D3-rich, pure and potent supplements are essential, now and always. You can achieve adequate levels of Vitamin D3 when you choose a supplement that is better absorbed by your body.

Based on extensive research and our clinical observations, I recommend the following dosages.

Age Vitamin D3 Dosage Notes
Infants under 2 Daily doses of 600 – 800 IU. Both the United States and Canada mandate the fortification of infant formula with vitamin D: 40–100 IU/100 kcal in the United States and 40–80 IU/100 kcal in Canada, and the ranges are similar here.
Please note: if supplementing infants with extra vitamin D, take the amounts in formulas or dairy products into account. Over 1,500IU in infants is potentially harmful taken over longer periods.
2-13 year olds 1,000IU daily


Given on days there is no time in the sun. This can be taken daily through the winter months, and discontinued when children are playing outdoors and are having approx 20 minutes without sun-cream applied.
14 years to adulthood Initial loading: 2,000 – 3000 IU daily for one to two months.
Maintenance: 1,000IU daily.
Don’t guess, test. Measure your blood levels to ensure you’re achieving 30-50ng/mL.
For teens and those that do sports in the sun, we recommend 2,000IU for 1 month. After that, switch to 1,000IU daily.
Overweight individuals will typically need higher initial doses i.e. 3,000IU for 2 months. Then, switch to 1,000 daily.

With the colder months fast approaching, it’s important to note that – unless there has been a holiday in the sun – an initial loading dose is nearly always required in the winter. While there are many signs and symptoms of Vitamin D deficiency, muscle or joint pain – or growing pains in children – is often an early indicator of sub-optimal Vitamin D level. Of course, it’s best to test, not guess. For parents’ peace of mind, in particular, we can test your child’s Vitamin D blood levels with a simple and accurate blood test to ensure accuracy of dosing. If levels are under the optimal level of 30 ng/mL, sun or supplementation is advised. We then reduce, though do not stop supplementing, at 40 ng/mL.

Does Vitamin D help protect against other respiratory conditions?

Long before the pandemic, experts advised that Vitamin D3 is important for immunity. The ‘sunshine vitamin’ works in several ways to boost immunity, especially upper respiratory infections and conditions:

  • Increases your levels of antiviral and antibacterial peptides (called cathelicidins and defensins) that line your lung epithelium (the first layer inside the nose and lungs).
  • Increases your immune system’s white blood cells (the neutrophils, natural killer cells, monocytes and macrophages), which are the first white cell responders to infection. Vitamin D is proven to quickly help to activate and strengthen your responses against respiratory infections7.
  • Vitamin D, along with Vitamin A and Zinc, support the more targeted immune response, antibody production, which follow about 8-10 days into an infection. At the same time Vitamin D reduces excessive inflammation that might otherwise occur if the patient is deficient.

A plethora of studies prove that Vitamin D significantly reduces the risk of respiratory infections, chronic lung infections and asthma attacks. Here are some of the stats:

Occasional doses of vitamin D can reduce the risk of upper respiratory tract infection by 36%, while daily doses can reduce the risk by 49%, according to a group of 25 studies covering almost 11,000 people from birth to 95 years of age across 14 countries on four continents8.

Vitamin D3 supplementation can significantly benefit those with chronic lung conditions, as well as those with asthma. A team of researchers in the UK found seven trials involving 435 children and two studies, involving 658 adults. The majority of people recruited to the studies had mild to moderate asthma, and a minority had severe asthma. Most people continued to take their usual asthma medication while participating in the studies, which lasted for between six and 12 months. Giving an oral vitamin D supplement reduced the risk of severe asthma attacks requiring hospital admission or emergency department attendance from 6% to around 3%. It also reduced the rate of asthma attacks needing treatment with steroid tablets9.

Another large study of a chronic lung condition, COPD, showed similarly impressive reduction in respiratory tract infections when taking Vitamin D daily10.

This gives even more reason to overcome Vitamin D-deficiency, now and always.


  1. Biesalski HK. Vitamin D deficiency and co-morbidities in COVID-19 patients – A fatal relationship?. Nfs Journal. 2020;20:10-21. doi:10.1016/j.nfs.2020.06.001.
  2. PLOS ONE | September 25, 2020.
  3. PLOS ONE | September 25, 2020.
  4. PMID: 32700398
  5. PMID: 32871238
  6. JAMA Netw Open. 2020;3(9):e2019722. doi:10.1001/jamanetworkopen.2020.19722.
  7. Rejnmark L, Bislev LS, Cashman KD, Eiríksdottir G, Gaksch M, Grübler M, et al. (2017) Non-skeletal health effects of vitamin D supplementation: A systematic review on findings from meta-analyses summarizing trial data. PLoS ONE 12(7): e0180512.
  8. PMID: 23840373
  9. Martineau AR, Cates CJ, Urashima M, Jensen M, Griffiths AP, Nurmatov U, Sheikh A, Griffiths CJ. Vitamin D for the management of asthma. Cochrane Database of Systematic Reviews 2016, Issue 8. Art. No.: CD011511. DOI:10.1002/14651858.CD011511.pub2.
  10. PMID: 27799758


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