As numerous strains of the influenza virus continue to pose a deadly danger to the public health—especially among aging individuals—a potent, low-cost defense has been hidden in plain sight: vitamin D.
The work of several pioneering experts suggests that at sufficient levels, its capacity to supercharge the immune system can virtually eliminate the risk of infection. Their findings also underscore the extraordinary inadequacy of the current “recommended” dose of 400-800 IU/day. To get the full immune-boosting benefit, about ten times that amount may be required to achieve optimal blood levels of vitamin D in its active form.1
Mainstream medicine’s persistent failure to recognize and ensure adequate D levels has resulted in epidemic deficiency—87% of adults by recent estimates. 2,3 Given seasonal flu viruses’ ability to endlessly mutate, and the exorbitant cost to the public for each new round of vaccination, this persistent “oversight” borders on the criminal.
In this article, you will find compelling evidence that vitamin D provides unrivalled support for the innate immune system: the foundation of your body’s defense that is hard-wired to respond instantly to microbial invasion.4
You will also discover how you may be getting the wrong test to determine your vitamin D status—and the right steps to take for maximum immune support.
An “Accidental Experiment”
The recent work of three exceptional physicians illustrates vitamin D’s vastly underreported preventive power.
Dr. John Cannell’s “accidental experiment” with vitamin D took place in 2005.5 A psychiatrist based at a locked facility in California, Cannell found himself confronted with a particularly severe outbreak of seasonal influenza that year. A substantial number of inpatients were infected—and most of the wards were forced into quarantine. By contrast, not one of the 32 patients in Dr. Cannell’s care developed flu symptoms.
The reason soon came to light. In contrast to those in the rest of the hospital, his patients’ treatment regimen included high-dose vitamin D. Dr. Cannell knew its critical role in the optimal functioning of multiple systems in the body. He was also aware that his patients were unlikely to get the amount of sunlight required to support healthy vitamin D levels on their own.6 (Vitamin D synthesis requires exposure to ultraviolet light from the sun.)
The 100% rate of flu protection was unexpected, and it prompted Cannell to perform further research. After exploring the scientific literature and consulting with experts, Cannell and his colleagues developed a novel theory: influenza is seasonal because of seasonal variations in sunlight, which cause natural fluctuations in vitamin D levels.4,7
That initial exploration has now led to a wealth of scientific support, including compelling data on exactly how vitamin D dramatically increases immunity to many infectious diseases. It has also led other physicians to include D supplementation as part of their standard treatment regimen.
Norris Glick, MD, is Director of Rehab Services at Central Wisconsin Center, a long-term care facility for people with developmental disabilities, with 275 residents and 800 staff members. Like Dr. Cannell, Dr. Glick monitors his patients’ vitamin D and supplements them to maintain adequate levels. In a published letter to Dr. Cannell, Dr. Glick reported that during the H1N1 (“swine flu”) outbreak of June 2009, only two patients (0.7%) developed influenza-like symptoms.8 During the same period, 103 staff members (7.5%) developed influenza-like illnesses—a 10-fold difference. Dr. Glick concluded that “staff were susceptible [to infection] while our residents were protected.”Sadly, when Dr. Glick presented these findings to the state agency charged with “protecting and promoting the health and safety of the people of Wisconsin”,9 he was unable to generate interest in studying them further.8
Dr. Ellie Campbell, an integrative family medicine practitioner in Georgia, where widespread H1N1 outbreaks have been reported, outlined similar findings in September 2009.8 Campbell measures and replenishes vitamin D in her patients, while the family physician who shares her office does not. During the 2009 outbreak, he was seeing up to 10 cases per week of influenza-like illness, while Campbell had seen just one over the same period.
Campbell attributes this striking contrast in infection rates to her patients’ vitamin D status. “I’m a prevention doctor, and I don’t have a tool in my kit more powerful than vitamin D,” she says. “I test virtually all of my patients every three to six months for vitamin D status,” Campbell continues, “and I aim for a vitamin D ‘sufficiency’ level of 50-80 ng/mL.” Like many vitamin D-aware physicians, Campbell considers levels below 30-40 ng/mL to be insufficient.10-13
Drs. Cannell, Glick, and Campbell achieved these superior results through their knowledge of vitamin D’s powerful impact on the innate immune system.
Bolstering the Body’s Fundamental Defenses
The innate immune system is the branch of the immune system that responds immediately to dangerous microbes.4 As soon as an invasion is detected, the innate immune system releases virus-killing compounds called antimicrobial peptides (AMPs).14-17 The tissues that line our air passages are especially rich in AMP-producing cells, where they provide a front-line defense against influenza.16-20
Only in the past few years have scientists discovered that these cells require vitamin D to function effectively.4,20-23 Vitamin D acts by modulating gene expression—activating the genes that govern AMP production.15,18-25 Respiratory tract cells convert vitamin D into its active form—reflecting the intimate relationship between vitamin D and host defenses.18
Vitamin D also suppresses inflammatory cytokines.4,25-27 Cytokines are partly responsible for the pain, fever, and congestion that comes with influenza infection; full-blown cytokine storms are to blame in some fatal cases of influenza.4,28 Vitamin D not only enhances our ability to produce AMP molecules, it also simultaneously dampens the acute inflammation that causes most of our symptomatic misery during a bout of influenza.4
While the underlying mechanisms behind vitamin D’s immune-supporting action have only recently come to light, scientists have long suspected that vitamin D protects against influenza and other respiratory infections. Influenza is highly seasonal, of course, occurring during months of relative darkness in both hemispheres (both through fewer daylight hours and greater cloud cover). Since vitamin D requires sunlight for activation, researchers suspected a connection.7,29,30
An early study demonstrated that mice with low vitamin D levels were at higher risk for experimental swine flu.31 Numerous studies have shown that infants, children, and adults are at increased risk for influenza and other serious lower respiratory infections when their vitamin D levels decline.32-36 One 2009 study found that risk was 36% greater for healthy people with vitamin D levels below 30 ng/mL, and 126 to 467% greater for those with chronic obstructive pulmonary disease or asthma, respectively!37
A 2005 placebo-controlled study revealed a direct link between vitamin D supplementation and flu prevention.38 Researchers studying a group of postmenopausal women at risk for osteoporosis administered the recommended 800 IU per day of vitamin D3 for the two years, then 2,000 IU per day in the third year, vs. placebo. While 26 placebo recipients reported having a cold or influenza-like illness during the study, only 7 taking the 800 IU supplement had such an illness—and only one such illness was reported during the 2,000 IU period. Even more unexpectedly, the supplement completely cancelled out the seasonality of infection—there was no big “flu spike” in winter among the supplemented patients.11
These results provide ample evidence that the immune system requires vitamin D in relatively high quantities to provide adequate protection against the flu (including H1N1 swine flu). The problem is that even if you take vitamin D supplements, you may still not be getting enough.
Why You Aren’t Getting Enough Vitamin D
The current “recommended” daily amount of 400-800 IU was established more than 30 years ago—and it was aimed purely at establishing the minimum required to avoid osteoporosis.39 These amounts are far too low to provide vitamin D at immune-supporting levels.40 The body can produce blood levels of activated vitamin D in far greater amounts than we normally ingest.11 In order to generate any significant benefit, researchers had to give 6,400 IU of vitamin D to healthy adults in order to maximize production of the active form.10 As Dr. Cannell reported, “This implies that everyone has a chronic vitamin D deficiency, at least in the winter,” when flu is at its worst.11
Recent studies support Cannell’s observation, demonstrating that as many as 87% of adults are vitamin D deficient by late winter—and 61% remain deficient even during the sunny summer months.2,3 Many factors contribute to these low levels. Age decreases the ability of human skin to activate vitamin D.41 Pollution and cloudy skies cut down on the amount of sunlight available for natural vitamin D activation, as does living in the temperate zones where total sunlight levels are only moderate.42,43
According to nutritional expert Reinhold Vieth, “Human biology was probably optimized through natural selection for a sun-rich environment that maintained serum vitamin D higher than 40 ng/mL. These levels are now only prevalent in people who spend an above-average amount of time outdoors, with the sun high in the sky.”44 Vieth continues, “The combined effect of current nutrition guidelines and current sun-avoidance advice is to ensure that adults who follow these recommendations will have circulating vitamin D concentrations lower than 30 ng/mL.”
Experts who have devoted their lives to the study of vitamin D conclude that the lower end of the current RDA is far too low.5,13,45 Studies show that you need at least 2,200 IU vitamin D daily total and probably much more, in order to come anywhere close to optimizing vitamin D status for real immune support.46 Yet most doctors are not recommending supplementation greater than 800 IU!11