Vitamin D & Respiratory Infectious Diseases – Part I
- A scientific review published in 2006 concluded that epidemic seasonal influenza is most likely related to the prevalence of vitamin D deficiency during winter months. Since then, other studies have confirmed this theory.
- A 2010 study found there’s an inverse relationship between UVB sun exposure — which is how your body synthesizes vitamin D naturally — and influenza deaths.
- Vitamin D protects against tuberculosis, a fatal lung disease that kills an estimated 1.8 million people around the world each year.
- According to recent research, 82.2% of COVID-19 patients tested were found to be deficient in vitamin D, and vitamin D status has been shown to influence your risk of testing positive for COVID-19, hospitalization rates and need for intensive care, as well as your risk of dying from the infection.
- Vitamin D can reduce your risk of COVID-19 and other respiratory infections by reducing the survival and replication of viruses, reducing inflammatory cytokine production, maintaining endothelial integrity and increasing ACE2 concentrations, which helps lower COVID-19 severity.
As temperatures drop, rates of respiratory infections — the common cold and influenza, primarily — increase exponentially. Many believe this has to do with the drop in temperature, but cold exposure actually ramps up your immune system, making you less prone to infection.
According to a 2002 study1,2 by the U.S. and Canadian armies, cold exposure can double the number of natural killer (NK) cells in your body, which are part of your first line of defense against pathogenic infiltration and other types of cell damage.
As detailed by retired nurse and academic teacher John Campbell, a scientific review3 published in 2006 concluded that epidemic seasonal influenza is most likely related to the prevalence of vitamin D deficiency during winter months.
“In 1981, R. Edgar Hope-Simpson proposed that a ‘seasonal stimulus’ intimately associated with solar radiation explained the remarkable seasonality of epidemic influenza.
Solar radiation triggers robust seasonal vitamin D production in the skin; vitamin D deficiency is common in the winter, and activated vitamin D, 1,25(OH)2D, a steroid hormone, has profound effects on human immunity.
1,25(OH)2D acts as an immune system modulator, preventing excessive expression of inflammatory cytokines and increasing the ‘oxidative burst’ potential of macrophages.
Inverse Relationship Between Flu Deaths and UVB Exposure
While vitamin D has been linked to many health benefits, the relationship between vitamin D and infectious disease is particularly robust. For example, a 2010 study6 by Norwegian researchers found there’s an inverse relationship between UVB sun exposure — which is how your body synthesizes vitamin D naturally — and influenza deaths.
“Non-pandemic influenzas mostly occur in the winter season in temperate regions. UVB calculations show that at high latitudes very little, if any, vitamin D is produced in the skin during the winter.
Even at 26°N (Okinawa) there is about four times more UVB during the summer than during the winter. In tropical regions there are two minor peaks in vitamin D photosynthesis, and practically no seasonality of influenza.
Pandemics may start with a wave in an arbitrary season, while secondary waves often occur the following winter. Thus, it appears that a low vitamin D status may play a significant role in most influenzas The data support the hypothesis that high influences of UVB radiation (vitamin D level), as occur in the summer, act in a protective manner with respect to influenza.”
Perhaps most importantly, it dramatically stimulates the expression of potent anti-microbial peptides, which exist in neutrophils, monocytes, natural killer cells, and in epithelial cells lining the respiratory tract where they play a major role in protecting the lung from infection.”
Vitamin D Protects Against Fatal Lung Disease
Other studies 8,9,10 have confirmed the long-held belief that vitamin D protects against tuberculosis, a fatal lung disease that kills an estimated 1.8 million people around the world each year. This is largely related to vitamin D stimulating antimicrobial peptides (AMPs) like cathelicidin (LL37).
In the past, tuberculosis was treated by making sure patients got plenty of sun exposure. In fact, Finsen was given the Nobel Prize in 1903 for this determination. Around the turn of the 20th century regular sun exposure was the most effective clinical strategy for the treatment of tuberculosis, but was eventually phased out with the development of antibiotics.
A 2011 study in Science Translational Medicine examined the mechanisms responsible for your immune system’s ability to ward against tuberculosis, concluding that T cells play a central role. They release a protein called interferon-g, which in turn activates the release of AMPs so your immune cells can mount an effective attack against the tuberculosis bacteria.
However, in order for this activation to occur, you have to have sufficient levels of vitamin D. In patients with low vitamin D levels, this immune response was not activated. Meanwhile, among those with adequate levels, there was an 85% reduction of colony-forming tuberculosis bacteria. As reported by UCLA:12
“The team noted that vitamin D may help both innate and adaptive immunity, two systems that work synergistically together to fight infections. Previous research by the team found that vitamin D played a key role in the production of a molecule called cathelicidin, which helps the innate immune system kill the tuberculosis bacteria.
Humans are born with innate immunity, which is the preprogrammed part of the immune system. The current research findings demonstrate that vitamin D is also critical for the action of T cells, key players in adaptive immunity, a highly specialized system that humans acquire over time as they encounter different pathogens.”
More Than 80% of COVID Patients Are Vitamin D Deficient
Currently, the respiratory infection of note is of course COVID-19, and vitamin D appears to have a lot to do with your risk of this infection as well. According to a Spanish study 13,14,15 published online October 27, 2020, in The Journal of Clinical Endocrinology & Metabolism, 82.2% of COVID-19 patients tested were found to be deficient in vitamin D.
“In COVID-19 patients, mean± SD 25OHD levels were 13.8±7.2 ng/ml, compared to 20.9 ±7.4 ng/ml in controls. 25OHD values were lower in men than in women. Vitamin D deficiency was found in 82.2% of COVID-19 cases and 47.2% of population-based controls.
25OHD inversely correlate to serum ferritin and D-dimer levels. Vitamin D deficient COVID-19 patients had a greater prevalence of hypertension and cardiovascular diseases, raised serum ferritin and troponin levels, as well as a longer length of hospital stay than those with serum 25 OHD levels ≥ 20 ng/ml.”
While this particular study failed to find a correlation between vitamin D levels and disease severity, other studies have shown patients with higher levels do tend to have milder disease. In fact, one such study 17,18 found your risk of developing a severe case of, and dying from, COVID-19 virtually disappears once your vitamin D level gets above 30 ng/mL (75 nmol/L).
“SARS-CoV-2 positivity is strongly and inversely associated with circulating 25(OH)D levels, a relationship that persists across latitudes, races/ethnicities, both sexes, and age ranges. ~ PLOS ONE September 17, 2020”
Other research19 looking at vitamin D and COVID-19 mortality found those with a vitamin D level between 21 ng/mL (50 nmol/L) and 29 ng/mL (75 nmol/L) had a 12.55 times higher risk of death than those with a level above 30 ng/mL. Having a level below 20 ng/mL was associated with a 19.12 times higher risk of death.
Information taken from Dr Joseph Mercola
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