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Information on the latest vitamin D news and research.

Find out more information on deficiency, supplementation, sun exposure, and how vitamin D relates to your health.

Dear Dr Cannell: Flu season hits early

It is the flu season. The CDC reported widespread influenza activity in 41 states last week. Influenza kills about 350,000 people in the world, almost all in the winter. Older adults with chronic illnesses are at the highest risk.

I often get questions about influenza like this one:

Dear Dr. Cannell:

The news this week was all about the “flu spike.” Is it too late to get the flu shot? Is it your recommendation to increase dosage of vitamin D or stay on the usual 5,000 IU/day? What about massive doses if I get the flu, like 50,000 IU/day for several days?


Andy, Seattle

Dear Andy:

The flu has spiked early this year with more than the expected number of cases for this time of year.

Sun LH. Early flu season could be severe, experts warn. Washington Post-Dec 29, 2012

I have always recommended the flu shot, just to cover all possible bases. I also recommend that healthy people keep their vitamin D levels in a natural range, about 50 ng/ml. If one has a chronic illness, I think it wise to keep your 25(OH)D level in the higher range of normal, such as 70-80 ng/ml, although to date no evidence supports such a recommendation.

As far as high daily doses for a few days after getting ill, such as 50,000 IU/day for several days, our group first hypothesized such doses may help treat influenza and we so hypothesized back in 2006. Our reasoning was simple, vitamin D upregulates a naturally occurring anti-microbial peptide, cathelicidin, in humans, antimicrobial peptides that are active against influenza. Recently, scientists discovered that this action of cathelicidin is dose dependent, the more cathelicidin, the more influenza virus killed.

Tripathi S, Tecle T, Verma A, Crouch E, White M, Hartshorn KL. The human cathelicidin LL-37 inhibits influenza A viruses through a mechanism distinct from that of surfactant protein D or defensins. J Gen Virol. 2013 Jan;94(Pt 1):40-9.

We assume, and this has not been proven, the more vitamin D in the blood, the more cathelicidin antibiotic in the immune system. Thus giving “massive” doses for a few days may help. Actually, 50,000 IU/day is not a massive dose; it is a pharmacological dose. If it helps treat influenza, and I suspect it will, then a bottle of 50,000 IU capsules from the only company that makes such a preparation, Bio Tech Pharmacal, is a good drug to keep in your medicine cabinet.

Finally, be careful. While 50,000 IU/day over a few days or a week is fine, it is not a dose to be taken every day for long periods of time, like several months or longer.

  About: John Cannell, MD

Dr. John Cannell is founder of the Vitamin D Council. He has written many peer-reviewed papers on vitamin D and speaks frequently across the United States on the subject. Dr. Cannell holds an M.D. and has served the medical field as a general practitioner, emergency physician, and psychiatrist.

3 Responses to Dear Dr Cannell: Flu season hits early

  1. Rita and Misty says:

    I found attached link interesting. It speaks to the complications associated with the flu vaccination. Read and make your own decision….I received the flu vaccination for years, and almost always came down with the flu…This year I passed on the vaccination. We shall see!


    Let me add that I agree that vaccinations (in general) are a wonderful thing….and, I am certainly not advocating to others to make the choice I’ve made…as a matter of fact, if I were elderly, or suffering from a chronic illness, etc., I would have been certain to receive the flu vaccination this year (most likely, I would have been one of the first in line–lol)….I’m simply keeping my fingers crossed that my 25(OH)D level, which is in the higher range of normal, will keep me healthy this winter…I am an experiment of one…and we shall see if I have any success. But, as we know, every solution does come with its own unique set of problems, doesn’t it?

    Vitamin D and the anti-viral state: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3308600/

    Vitamin D and the anti-viral state


    Wishing everyone a healthy winter,

    Rita Celone Umile

  2. Mike_Hinton says:

    I was waiting for this story. I have never really gotten the flu, even before I started taking D. My whole life I’ve done my best avoiding desease, getting better at it over time. Now I feel near invincible. I have gotten flu shots since they’ve been free for me, now I have Vitamin D as insurance.

    I’m currently a believer in everything: conventional medicine, and now I’ve added supplements. I just do my best and make sure I avoid what is potentially harmful (no super high doses of anything).

    I think, in the end, Dr. Gominak will be proven right and the majority of Vitamin D’s general non-desease benefit is due to improved deep sleep, allowing our bodies to heal themselves as much as possible. 4 months after getting my D above 60 ng/ml and I no longer get up durring the night, huge decrease in migraines, and I’m starting to notice improvements every day. I no longer have athletes foot after suffering off and on for years (anti-microbial peptides?). I’m excited by the possibility that I saw this revolution early on.