Does Vitamin D Actually Boost the Immune System? What 200 Scientists & Doctors Have to Say.


At first glance, Vitamin D may seem like all your other basic nutrients.  Lately though, scientists are learning more about immunity and Vitamin D, especially since the onset of Covid-19.  There's a mountain of new evidence, that's growing every day, as researchers figure out how D3 affects our immune system when it's exposed to respiratory viruses.  

Why 200 Scientists and Doctors are Calling for Vitamin D3 to Treat Covid-19

With concerns about more contagious variants on the rise, in February 2021, an open letter addressed to all governments, public health officials, doctors, and healthcare workers was signed by 200 scientists and doctors, calling for increased vitamin D usage to combat COVID-19.

In this post we'll unpack the latest data that was included in the open letter. You'll find out why doctors feel its so essential and we'll help you determine if you're getting enough Vitamin D3 to keep your immune system working at optimum levels. 

One key finding that prompted this letter is evidence that suggests that the COVID-19 virus sustains itself by infecting people with low vitamin D, and that the risk of death is much higher among people who have a deficiency.  According to the letter, evidence also indicates that "increased vitamin D would help reduce infections, hospitalizations, ICU admissions, & deaths."


 How Vitamin D3 May Protect Against Viral Respiratory Infections 

In a large study published in the British Medical Journal, an evaluation found that when patients with vitamin D deficiency were given daily or weekly vitamin D supplementation, their respiratory tract infection rate dropped by 70%.  Even in people without vitamin D deficiency, the rate of respiratory infections dropped by 25% after supplementation. 

In a second study, the death rate due to viral respiratory tract infection was nearly 100% in patients whose vitamin D levels were below 19 ng/ml.  While 50 ng/ml and higher is considered optimal, this study showed that the critical vitamin D level for reducing mortality in respiratory infections is at least 34 ng/ml.


How Do I Know if I Have Vitamin D Deficiency?

In Canada, approximately 1 in 3 people have less than optimum vitamin D3 levels. Although you may have access to some common dietary sources of vitamin D - in foods like egg yolks, oily fish and fortified milk beverages, these sources are generally not enough for most people to meet optimum vitamin D levels.

There are a number of other factors that may put people at increased risk of Vitamin D deficiency, including:

  •  Minimal exposure to sunlight –spending the majority of time indoors or covered by long sleeve clothing or sunscreen when outside. 
  • Darker skin – the skin pigment melanin reduces the effects of ultraviolet rays on the skin, thereby reducing vitamin D formation. The darker the skin, the greater the risk of vitamin D deficiency.
  • Obesity, liver disorders, and type 2 diabetes  – these conditions reduce the conversion of D3 by the liver.
  • Aging – Over the age of 50, our skin becomes less a responsive to ultraviolet light.

One of the Best Immune System Boosters:

While sun exposure has a number of health and mood benefits, for most people, a daily supplement will be needed for people to reach and maintain safe levels of vitamin D.  If you haven't been taking vitamin D regularly, or you're not sure if you're taking enough, you may want to have your blood levels checked by your health care provider, and ask for their recommended loading dose for the first few weeks help get your body to a safe level.  

In support of the open letter signed by 200 experts, Former US Surgeon General, Dr. Richard Carmona recently wrote: “We are often enamored by high tech treatments but the history of medicine is replete with examples of commonly overlooked basic nutritional physiology…In the face of the deadly COVID-19 pandemic, their encouragement to consider widespread vitamin D supplementation has little chance of harm but a tremendous potential for good.”

Here are the two key takeaways. The bad news: A high number of people suffer from low vitamin D, which can greatly increase the risk of serious viral infections. The good news: boosting your body up to optimum levels of Vitamin D is safe, easy and inexpensive. 

Why not start now! It's time to build your family's immunity toolkit. Would you like a "one and done" supplement? Try Natural Factors Super Immune Formula, which combines 7 essential nutrients into one powerful capsule!


  1. Pham H, Rahman A, Majidi A, Waterhouse M, Neale RE. Acute Respiratory Tract Infection and 25-Hydroxyvitamin D Concentration: A Systematic Review and Meta-Analysis. Int J Environ Res Public Health. 2019;16(17):3020. Published 2019 Aug 21. doi:10.3390/ijerph16173020
  2. Martineau Adrian R, Jolliffe David A, Hooper Richard L, Greenberg Lauren, Aloia John F, Bergman Peter et al. Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data BMJ 2017; 356 :i6583








1 comment

  • Elizabeth

    Thanks for sharing this information! I’m going to increase my vitamin D intake.

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