There is important data that suggests maintaining your Vitamin D3 level in the optimal range may protect you from colds and flu. Recognizing the importance of these data, Canadian health authorities have initiated studies to determine whether maintaining Vitamin D3 levels will reduce the severity of flu, such as H1N1 that threatens to become an epidemic this winter.

Canada's public health agency has announced plans to analyze the effect of Vitamin D3 levels on the severity of flu symptoms. The study was launched last year with the intention of studying Vitamin D3's impact on seasonal influenza. However, as fear of an H1N1 (formerly known as Swine flu) epidemic spreads around the world, the agency has modified the study plan to explore Vitamin D3's effect on the severity of H1N1 infections. This may quickly lead to a recommendation to use Vitamin D3 as a supplement to lessen the severity of the illness. The Canadians clearly take Vitamin D3 deficiency seriously. More than two years ago the Canadian Cancer Society recommended taking the supplement daily to help prevent cancer, something that is not widely known. 

However, with regard to Vitamin D3 and its effect on influenza, it may not be necessary to wait for results of the Canadian study. There is already a wealth of data showing that Vitamin D3 levels play a significant role in the likelihood of contracting the flu.

Dr. Cannel, founder of the Vitamin D3 Council, has published two papers on this topic. The first was two years ago in the journal Epidemiology and Infection and another last year in Virology Journal. Click on these links for summaries of these papers. Dr. Cannel proposed in these publications that many of the characteristics of winter colds and influenza can be correlated with low Vitamin D3 levels. He summarized his hypothesis as follows:

1. Why the flu predictably occurs in the months following the winter solstice, when Vitamin D3 levels are at their lowest,

2. Why it disappears in the months following the summer solstice,

3. Why influenza is more common in the tropics during the rainy season,

4. Why the cold and rainy weather associated with El Nino Southern Oscillation (ENSO), which drives people indoors and lowers Vitamin D3 blood levels, is associated with influenza,

5. Why the incidence of influenza is inversely correlated with outdoor temperatures,

6. Why children exposed to sunlight are less likely to get colds,

7. Why cod liver oil (which contains Vitamin D3) reduces the incidence of viral respiratory infections,

8. Why Russian scientists found that Vitamin D3-producing UVB lamps reduced colds and flu in schoolchildren and factory workers,

9. Why Russian scientists found that volunteers, deliberately infected with a weakened flu virus - first in the summer and then again in the winter - show significantly different clinical courses in the different seasons,

10. Why the elderly who live in countries with high Vitamin D3 consumption, like Norway are less likely to die in the winter,

11. Why children with Vitamin D3 deficiency and rickets suffer from frequent respiratory infections,

12. Why an observant physician (Rehman), who gave high doses of Vitamin D3 to children who were constantly sick from colds and the flu found the treated children were suddenly free from infection,

13. Why the elderly are so much more likely to die from heart attacks in the winter rather than in the summer, and

14. Why African Americans, with their low Vitamin D3 blood levels are more likely to die from influenza and pneumonia than Caucasians.

In February 2009 another paper published in the Archives of Internal Medicine strongly supported these observations. In this study Vitamin D3 levels were measured in over 19,000 Americans, and those with the lowest levels reported having significantly more cases of colds or flu.

Dr Adit Ginde, the lead author of the paper, offered the following conclusion:

"The findings of our study support an important role for Vitamin D3 in prevention of common respiratory infections, such as colds and the flu. Individuals with common lung diseases, such as asthma or emphysema, may be particularly susceptible to respiratory infections from Vitamin D3 deficiency."
In addition, two new studies published in 2009 have suggested that low Vitamin D3 levels in newborns make them more susceptible to viral infections. In the first study over 87 percent of all newborns with acute lower respiratory tract infections had vitamin D3 levels lower than 20 ng/ml, which is a severe deficiency state.  The second study concluded:

"Based on the available evidence showing a strong connection between Vitamin D3, infections and immune function in children, Vitamin D3 supplementation may be a valuable therapy in pediatric medicine".

There is also significant laboratory data to substantiate these findings. In a review article Cell Defenses and the Sunshine Vitamin published in Scientific American in 2007, the authors explain how Vitamin D3 has been shown to activate multiple genes in just about every tissue in the human body. In particular, Vitamin D3 activates two genes that encode antimicrobial peptides called cathelicidin and defensin beta 2. These small proteins act as natural antibiotics against a wide spectrum of bacteria, viruses and fungi. In studies conducted with cultured human cells they found that exposure to Vitamin D3 caused an increase in the cells ability to manufacture both the defensin beta 2 peptide and cathelicidin. In some cell types the rise in cathelicidin production was dramatic.

Clearly, both laboratory and clinical data supports the concept that maintaining a high level of Vitamin D3 may protect from both colds and flu.

What is a Healthy Vitamin D Level?

It's important to realize that what's conventionally considered normal is NOT the same as optimal.

In this latest study, those whose Vitamin D3 levels were below 10 ng/mL had a 36 percent greater risk of getting a cold, and those with levels between 10-30 ng/mL experienced a 24 percent greater risk compared with participants whose levels were at least 30 ng/ml.

However, most experts now agree that an optimal level of Vitamin D3 is between 50-90ng/ml. Based on the dose response shown above, i.e. the higher the level the lower the risk of URTI, if you were to maintain your Vitamin D3 levels in the optimal range, you would likely avoid being affected during the cold and flu season entirely.

More evidence that Vitamin D3 protects against H1N1, colds and flu.

We recently received a copy of an e-mail sent to Dr.Cannell, president of the Vitamin D council. It is from a physician who cares for institutionalized patients with developmental disabilities. These patients have their Vitamin D3 levels monitored regularly to ensure they are kept optimal. During a recent outbreak of H1N1 only two patients fell ill while 103 staff members (who don't have their levels monitored) developed an influenza-like illness.

Dear Dr. Cannell:

Your recent newsletters and video about Swine flu (H1N1) prompted me to convey our recent experience with an H1N1 outbreak at Central Wisconsin Center (CWC). Unfortunately, the state epidemiologist was not interested in studying it further so I pass it on to you since I think it is noteworthy.

CWC is a long-term care facility for people with developmental disabilities, home for approx. 275 people with approx. 800 staff. Serum 25-OHD has been monitored in virtually all residents for several years and patients supplemented with vitamin D.

In June, 2009, at the time of the well-publicized Wisconsin spike in H1N1 cases, two residents developed influenza-like illness (ILI) and had positive tests for H1N1: one was a long-term resident; the other, a child, was transferred to us with what was later proven to be H1N1.

On the other hand, 60 staff members developed ILI or were documented to have H1N1: of 17 tested for ILI, eight were positive. An additional 43 staff members called in sick with ILI. (Approx. 11-12 staff developed ILI after working on the unit where the child was given care, several of whom had positive H1N1 tests.)

So, it is rather remarkable that only two residents of 275 developed ILI, one of which did not develop it here, while 103 of 800 staff members had ILI. It appears that the spread of H1N1 was not from staff-to-resident but from resident-to-staff (most obvious in the imported case) and between staff, implying that staff were susceptible and our residents protected.

Norris Glick, MD
Central Wisconsin Center

Dr Cannells' update rapidly produced a report from another physician who routinely supplements her patients with Vitamin D3:

Dear Dr. Cannell:
Thanks for your update about the hospital in Wisconsin. I have had similar anecdotal evidence from my medical practice here in Georgia. We are one of the 5 states with widespread H1N1 outbreaks.
I share an office with another family physician. I aggressively measure and replete vitamin D. He does not.
He is seeing one to 10 cases per week of influenza-like illness.
In my practice-- I have had zero cases. My patients are universally on 2000-5000 IU to maintain serum levels 50-80 ng/ml.

Ellie Campbell,
DO Campbell Family Medicine 3925 Johns Creek Court
Suwannee GA 30024

Also this month, (Sept 2009) the CDC released a report in the September 4 issue of Morbidity and Mortality Weekly Report (MMWR) on the 36 children who have died from H1N1 in the USA to date. Almost two-thirds of the children who died had epilepsy, cerebral palsy, or other neurodevelopmental conditions like mental retardation.

All of these neurological conditions are associated with childhood Vitamin D deficiency. Exacerbating the problem further, many of these children take anti-convulsant drugs, which lower Vitamin D3 levels.

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   Vitamin D3 deficiency and its role in colds and influenzan influenza
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