Vitamin D and Viruses

Vitamin D and Viruses

In this time of viral awareness many people are reaching for exotic antiviral compounds (elderberry, colloidal silver, hydrogen peroxide, andrographis, etc), but here I would like to remind everyone to not overlook our most important nutrient, vitamin D.

Vitamin D and Immunity

Vitamin D (aside from countless other functions) is required for a well functioning immune system, and the immune system is our first line of defence against infections, both bacterial and viral.

This essential vitamin both activates the immune system’s defences, and serves to regulate the immune system (preventing it from being overactive, as with autoimmune conditions). (Study)

Vitamin D enhances the function of the immune system by elevating levels of T-cells and macrophages, both of which protect us from pathogens. (Study) And vitamin D deficiency is clearly linked to increased susceptibility to bacterial and viral infection, as well as immune-related ailments. (Study)

Clinical studies have proven that having low levels of vitamin D leads to increased risk of a wide variety of respiratory ailments, including asthma, chronic obstructive pulmonary disease (COPD), and even tuberculosis. (Study) And, given that a deficiency in vitamin D has also been shown to cause decreased lung function, being in such a state will definitely affect one’s ability to stave off respiratory infections. (Study)

Now, let’s have a close look at a couple of studies on vitamin D and respiratory infections, and then I will examine the effectiveness of gargling with a common substance.

Respiratory Infections

In 2017, the British Medical Journal published a paper in which researchers did a meta-analysis of 25 existing studies in order to investigate the effect of vitamin D on immunity against respiratory infections. While these studies did not focus on corona viruses, it should still apply to them, as all viruses operate similarly in the body, as does our immune system.

The results indicated that taking a moderate dose of vitamin D daily, or weekly, helps to protect users from respiratory infections, though, of course, the greatest benefit was observed among those who were most deficient in vitamin D. For those not deficient in vitamin D, there appeared to be approximately 1 in 20 people who could avoid getting a cold due to supplementing with D. However, for those with a severe vitamin D deficiency, 1 in 4 people avoided getting a respiratory infection.

The study concluded: “Vitamin D supplementation was safe and it protected against acute respiratory tract infection overall. Patients who were very vitamin D deficient and those not receiving bolus doses experienced the most benefit.” (Study)


The term used above, “bolus”, is defined as “a large dose of a substance given by injection for the purpose of rapidly achieving the needed therapeutic concentration in the bloodstream”. What this comment meant was, while daily or weekly doses of vitamin D conferred a protective benefit, this was not observed in those taking large, single doses.

This explains to me why a number of studies I found showed little or no benefit against respiratory ailments. Those studies were based on the popular medical approach to vitamin D research, which is to inject subjects with a huge amount of vitamin D, and let them ride it out for one or more months. (Example: Oral vitamin D3, in an initial bolus dose of 200, 000 IU and followed by monthly doses of 100, 000 IU.)

Vitamin D in the Lungs

Acute respiratory tract infections are responsible for an estimated 2.65 million deaths worldwide (figures from 2013). Observational studies have repeatedly found an association between low serum concentrations of 25-hydroxyvitamin D (the major circulating vitamin D metabolite), and susceptibility to acute respiratory tract infection (RTI).

One study pointed out the reason vitamin D is valuable in preventing RTIs is because it “supports induction of antimicrobial peptides in response to both viral and bacterial stimuli”. This study discovered the epithelial cells lining the lungs would kick in when a bacteria or virus was detected, and convert inactive vitamin D into active vitamin D, thereby improving immune function in the lungs. (Study)

Another study “evaluated whether oral vitamin D supplementation during the winter and early spring reduces the incidence of influenza and upper respiratory infections in patients with inflammatory bowel disease (IBD). A randomized, double-blind, controlled trial was conducted to compare the effects of vitamin D supplementation (500 IU/day) and a placebo.

CONCLUSIONS: Vitamin D supplementation may have a preventative effect against upper respiratory infection in patients with IBD but may worsen the symptoms of UC.” (Study)

The takeaway here is that even a dose as low as 500 IU offered some protection against lung infections, and that amount would be considered abysmally low by today’s standards (especially in the alternative health field).

I do find it unusual that patients with UC (ulcerative colitis) found symptoms to worsen, especially since another study (from 2019) comes to this conclusion: “This study confirms the existence of low serum vitamin D in patients with UC when compared to healthy controls. It also provides evidence of an existing relationship between disease extent and serum vitamin D.”

My guess is that the extremely low amount of vitamin D had absolutely no benefit for those with UC, allowing their ailment to follow its natural trajectory of worsening.

Better Than Gargling?

I found an interesting study which “undertook a randomized controlled trial to assess whether vitamin D3 supplementation (10,000 IU per week) versus placebo, and gargling, versus no gargling, could prevent viral, clinical upper respiratory tract infection (URTI) in university students”.

This led me off on a bit of a tangent as I tried to discover what they had gargled with (not defined in the study synopsis). I found the Japanese study which led these Canadian researchers to include it in their vitamin D experiment, and learned that, in Japanese populations, gargling has been found to significantly reduce incidence of upper respiratory tract infections (by approximately 35%).

In this Japanese study subjects were divided into three groups: a control group, one group to gargle with water, and one group to gargle with diluted povidone-iodine. In each case subjects were to gargle at least three times a day.

The incidence rate of first URTI was 0.26 episodes/30 person-days among control subjects. The rate decreased to 0.17 episodes/30 person-days in the water gargling group, and 0.24 episodes/30 person-days in the povidone-iodine gargling group.

The conclusion was: “Simple water gargling was effective to prevent URTIs among healthy people. This virtually cost-free modality would appreciably benefit the general population.

A bit surprising to me, as I am a big believer in the powerful antiseptic properties of iodine, so I was shocked to find out that water worked better than iodine. Of course, we do not know how diluted the iodine was, and perhaps a stronger formulation might have been more effective.


Now, back to our Canadian study, which “randomized 600 students into 4 treatment arms: 1) vitamin D3 and gargling, 2) placebo and gargling, 3) vitamin D3 and no gargling, and 4) placebo and no gargling.” Those given vitamin D received a weekly dose of 10,000 IU of vitamin D3 (oral capsule), and those who gargled were asked to gargle with tap water, twice daily.

Vitamin D3 treatment was associated with a significantly lower risk for laboratory confirmed URTI and with a significantly lower mean viral load measured as log10 viral copies/mL. Fewer students assigned to gargling experienced laboratory confirmed URTI, however this was not statistically significant.These results suggest that vitamin D3 is a promising intervention for the prevention of URTI.” (Study)

There are two interesting things at play here. One, the Japanese study showed significant protection from gargling, whereas the Canadian study found it to be “not statistically significant”. The only obvious difference is the Japanese subjects gargled three times daily, and the Canadian ones only twice daily.

Secondly, tap water? Is there something in Japanese water that we are unaware of?

The water supply in Japan has a different “hardness level” (an indication of the amount of minerals in the water) compared to the supply in Western countries: the water in Japan is mostly “soft water,” with a low mineral level.

Technically a “hard” water should be more antiseptic than a “soft” water, given it is more alkaline. Just guessing here, but perhaps a softer water is more able to pick up bacteria in the throat, allowing us to remove them with gargling (and spitting it out). Or, maybe the chlorine in tap water is antiseptic enough (Japan also uses chlorine in their tap water) to disinfect the throat, and the problem is that the Canadian study should have had the students gargle three times daily, instead of only twice. Curious.

Finally, I have a study suggesting that vitamin D deficiency leads to longer duration of ARI (acute respiratory infections): median duration in days: deficient group, 4 to 13; non-deficient groups, 2 to 8. (Study)

Conclusion While we do not yet have the research to prove vitamin D is effective against the new coronavirus strain, the above material does show it helps protect against common respiratory infections.

Bear in mind that deaths from the coronavirus, as from the Spanish Flu, mostly is a result of the patients developing pneumonia, in infection in the lungs. Therefore, any substance that protects the lungs from infection is as important as those things which support immune function, and fight off the virus, per se.

I would be remiss if I did not suggest NutriStart’s Quick D product here. Quick D is in a highly absorbable liquid form, emulsified into organic sunflower oil. One drop is equal to 1,000 IU of vitamin D, and given that I take, on average, 5,000 IU daily (skipping weekends), I find it more convenient to take 5 drops under the tongue, than to swallow 5 pills (at a meal containing fat). In fact, one can simply take 10 drops every 2 days, or even 25 drops once per week.

I will end by pointing out that if you do use pills, ensure that they are softgels (liquid filled in a fat medium) as opposed to tablets, which is the most poorly absorbed form of vitamin D.

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