Can Vitamin D Prevent Influenza?
After posting The Influenza Vaccine: You Can’t Make This Stuff Up a friend and fellow mom reached out to me. She told me how happy she was to see some real info cross her virtual desk because her news feed is usually filled with the myths and dangers of the influenza vaccine. She had even read that Vitamin D could save the population from influenza infection and jokingly blamed “Dr. Google” for her discovery of this one. And with her, I rolled my eyes as you just can’t make this stuff up.
I do my best to keep up-to-the-moment on the influenza front, given I’m a vaxxer Mom, but this Vitamin D theory was totally new to me. And as an influenza vaccine myth-buster, I needed to do some sleuthing and spread the news on Vitamin D.
Turns out, Vitamin D and its role in combating influenza is not a joke. Nor is it a myth. And the information I found about this relationship has been around for several years (the articles I found date back to 2012). So this is not some pop-culture rumor, either. The possibility that Vitamin D could actually combat “the flu”* is real.
Numerous studies, including those done with infants and the elderly (two populations at high-risk for complications from influenza), have shown promising results: vitamin D supplementation during the “flu” season decreases the incidence of influenza A and may decrease the duration of influenza symptoms. And the wonder doesn’t stop there: more research is needed, but taking a vitamin D supplement may also decrease the risk of the common cold and community-acquired pneumonia.
Well, I’ll be. Or should I say, well, I’ll D. Vitamin D is generally considered safe to consume in higher doses,** and one study on the effects of vitamin D in infants demonstrated a low risk of unwanted side effects in both the low-and high-dose groups. Could we have a wonder drug on our hands? While it’s too early to say, the buzz is certainly promising. And it’s not like vitamin D is difficult to come by, or expensive, and many of us are already taking it for bone health. In other words, vitamin is readily available and considered safe, so taking it probably can’t hurt.
So why vitamin D, of all things, to combat influenza? Well, the explanation is pretty elegant. Vitamin D, aka the “sunshine vitamin”, is produced in usable form in our bodies when our unprotected skin is exposed to UVB rays. But in the winter shorter days mean less available sunlight, and therefore less UVB, and colder days mean more clothing which further reduces bodily surface area exposed to sunlight. Both factors mean less opportunity for our bodies to produce vitamin D3 (the “active” form). This leads to overall lower levels of circulating D3 during the winter months and this coincides with influenza season. And given that vitamin D plays a role in fighting infection,*** no wonder researchers picked up the idea to explore the influenza/vitamin D relationship. Put a string of pearls on that one. (Interestingly, when researchers took a hard look at the infamous influenza A pandemic of 1918, they discovered that there were significantly fewer deaths in the western and southern U.S. states…the areas of the country that see more sunny days than the rest of the nation.)
Taking a vitamin D supplement is generally considered safe for the majority of people, and it’s certainly accessible and inexpensive. However, how much is an appropriate dose? Generally speaking, the Vitamin D Council (yes, that’s really a thing…) recommends that adults take between 5,000 and 10,000 international units (IU’s) daily and children 100 IU’s per kilogram daily (to determine the suggested dose for kids, divide your child’s weight in pounds by 2.2 and multiply by 100). An effective dose puts the blood level of vitamin D in the range of 40 to 60 nanograms/milliliter (ng/ml). As different persons will respond differently to the recommended dosing of vitamin D, a simple blood test is needed after several weeks on a consistent dose to determine whether your dose is in the effective range. Consult your doctor and your child’s pediatrician for testing.
The down side to the vitamin D epiphany: while certain results look promising, not all studies agree. There is conflicting evidence regarding whether vitamin D supplementation can improve the effectiveness of the annual influenza vaccine. Also, it doesn’t appear that vitamin D can fend off strains of influenza B, which the vaccine is formulated to do (so still get your influenza shots). And more research is needed to determine vitamin D’s effectiveness in fighting off the common cold. However, vitamin D is an accessible, inexpensive supplement that is considered safe for everyone and it even comes in the form of gummies, which makes it easy for kids to take. Remember, though, to ask your doctor before starting vitamin D and be sure to follow her instructions regarding taking it.
*When we talk about the “flu” we most often think of nausea, vomiting and diarrhea. But influenza, while nicknamed the “flu,” is completely different. Influenza is a respiratory illness that produces many symptoms similar to those of the common cold but is caused by different viruses and also infects the lungs.
**As always, consult with your physician and your child’s pediatrician before starting any new supplement, including Vitamin D.
***Vitamin D contributes to our bodies’ response to infection. When vitamin D3 binds to receptors on immune cells, inflammatory proteins called cytokines are decreased and proteins that fight infection are put into circulation. What’s more is vitamin D directs genes involved in immunity by stimulating the activation of a molecule called cathelicidin. Put that in your Jeopardy armamentarium.
Links/Resources:
grassrootshealth.net/blog/vitamin-d-prevent-flu-epidemic/
journals.lww.com/pidj/Fulltext/2018/08000/Preventive_Effects_of_Vitamin_D_on_Seasonal.5.aspx
www.ncbi.nlm.nih.gov/pmc/articles/PMC3649720/
www.ncbi.nlm.nih.gov/pmc/articles/PMC3897598/
www.ncbi.nlm.nih.gov/pmc/articles/PMC4463890/
news.harvard.edu/gazette/story/2017/02/study-confirms-vitamin-d-protects-against-cold-and-flu/
https://www.vitamindcouncil.org/health-conditions/influenza/#.W-LlPnpKiqA
