Is This Common Deficiency the Trigger for Flu Season?
What’s the most important thing you need to know about the upcoming flu season, beyond the public health messages about washing your hands and staying home if you’re sick? It’s that taking enough vitamin D to bring your blood levels up to 40-60ng/ml 25-OH may help protect you from getting the flu, as well as other colds and respiratory infections.
That means taking somewhere between 2,000 and 5,000 IU of supplemental vitamin D3 a day for the average adult in temperate zones, during the fall and winter. Your doctor can test you before and after you begin supplementing, if you want to be sure you’re getting enough. The Vitamin D Council has also arranged for discounted home testing kits to help you monitor your vitamin D levels.
John Cannell, MD, founder and executive director of the Vitamin D Council, a non-profit dedicated to spreading the word about the importance getting adequate vitamin D through a combination of sun exposure, supplementation and food sources, also suggests having enough 50,000 IU capsules of vitamin D3 on hand to take at the first sign of the flu. He recommends 1,000 IU per day for every 25 pounds of body weight.
Last August, says Dr. Cannell, researchers at the University of Auckland found that a single dose of 500,000 IU (half a million units) did no harm to the elderly and a month after the dose, their vitamin D levels were in the optimal range and two months after, they were deficient again. And by the way, Dr. Cannell, will be getting his flu shot, too, though he feels it won’t work quite as well considering his high levels of vitamin D. He feels that the risk of contracting Guillain-Barré syndrome from the vaccine is very low, considering his blood levels of vitamin D, and that even though the vaccine may not works as well due to the protective effects of vitamin D, that any source of immunity against the flu is a good thing.
Research has been accumulating on the potential of vitamin D to prevent infections and possibly even treat them. But the implications of vitamin D’s possible impact on seasonal influenza are a fascinating epidemiological story and one that could prove to have a “profound effect on its prevention” according to a study published in the Journal of Virology in May of 2008. So if you have a few minutes and you love puzzles, read on.
The Anomalies of Seasonal Flu
There are certain aspects to the disease we call influenza that are different from other viral infections we call colds. And you may be surprised by them, as I was.
1. Unlike colds, studies have shown that often, only one person in a family is affected by the flu. This suggests that the virus does not spread from one person to the next in a “serial” manner. Studies done during the 1918 pandemic, which had infected volunteers with full blown symptoms coughing and spitting and sharing nasal swabs with healthy volunteers, did not produce a single subsequent case of the flu in those volunteers! Subsequent studies where researchers tried to infect patients also showed that almost half of volunteers never got symptoms. This certainly coincides with my personal experience — it’s either me or my husband, but never both, that get the flu. And I never got it from my kids.
2. Flu breaks out seasonally at specific places, around the same latitude, around the globe, at the same time. It has done this for generations — more than 500 years that we know of. This is long before modern transportation systems and the evidence suggests that the flu is not spread from one location to another by people carrying the virus to an uninfected population. The flu appears to be dormant until activated by a seasonal cue.
3. Flu epidemics are explosive. A lot of people get it all at once, and then it ends pretty abruptly. Many people who are not immune don’t get it. (In the USA and France, the peak of 25 consecutive epidemics ended within 4 days of each other!)
4. Flu vaccines may not help prevent deaths. Despite increasing vaccination of the elderly for the last 15 years, there appears to be no decline in overall mortality rates due to the flu among the aged.
Hope-Simpson and the “Missing Factor”
British epidemiologist, R. Edgar Hope-Simpson, carefully studied influenza and wrote a book about it, The Transmission of Epidemic Influenza (Springer, 1992), arguing that the flu did not act like other contagious diseases and that there was some “missing seasonal factor” that caused the virus to activate. After exhaustive research on past epidemics, Hope-Simpson concludes that the facts did not support “sick to well” transmission as the main way the flu spreads. It’s not that you can’t infect people in the laboratory with a flu virus, but that the behavior of epidemics shows that that serial transmission from sick people to well people doesn’t explain the anomalies of how epidemics begin and end.
Hope-Simpson concluded, from all the evidence that he gathered, that flu epidemics have something to do with the sun (solar radiation) and that the flu is primarily spread by “good infectors” who carry the disease but have no symptoms who become infections by some “seasonal stimulus.”
Could Low Vitamin D Levels Be the Trigger for Flu Season?
While Dr. Cannell readily admits that vitamin D would not have stopped the 1918 flu pandemic, which had a virus that clearly overwhelmed immune systems around the world, his paper, supported by other leading researchers in the field, suggests that the seasonal stimulus Hope-Simpson was looking for may well be vitamin D deficiency. Flu kicks up at the same time that vitamin D levels begin to plummet, due to lack of production from adequate sun exposure. Even near the equator, flu outbreaks correspond with the rainy season when blood levels of vitamin D go down.
Vitamin D, we now know, could be called an “antibiotic vitamin” due to its effects on innate immunity. Innate immunity is not related to the resistance you build when exposed to a particular virus. It’s the body’s natural defense system that responds to invaders. Antimicrobial peptides protect mucous membranes by creating a shield that blocks viruses, bacteria and fungi. Vitamin D is critical to the activation of that natural defense system. So when the sun isn’t as strong, or weather obstructs it, blood levels go down rapidly and immunity suffers.
Then, speculates Cannell, those latent “good infectors” that do not display symptoms, set off epidemics because their lowered blood levels of vitamin D activate their virus and the people around them are suddenly much more vulnerable to the virus. (People who avoid the sun, or are deprived of sun, like nursing home residents, can be more vulnerable at any time during the year. Obesity and dark skin also make one vulnerable to lower blood levels of vitamin D.)
This theory may explain why the flu season ends so abruptly, rather than racing through a local population, sickening everyone who has not built up immunity. When the “good infectors” have past their point of being infectious, (which is usually just a few days) the transmission rates quickly recede. Even though a lot of people have flu symptoms, and you would expect more and more people to get sick, they don’t, because the super-infectors have passed through their period of ‘infectivity.’
The Anti-Aging Bottom Line: While his theory isn’t proven, Dr. Cannell suggests that because vitamin D is inexpensive and very safe, there is every reason to protect yourself by taking supplemental doses as the summer sun (or your exposure to it) fades and your natural immunity recedes.