The evidence keeps accumulating that adequate vitamin D may be really important for protecting people against the complications of the coronavirus (PLOS ONE, Feb. 3, 2022). Israeli researchers conclude: “Among hospitalized COVID-19 patients, pre-infection deficiency of vitamin D was associated with increased disease severity and mortality.” This is not the first study that demonstrates we should all have adequate amounts of Vitamin D for COVID-19.
The Israeli Study:
The investigators reviewed the medical records of patients admitted with a coronavirus infection. 253 had pre-infection vitamin D levels in their medical charts. Those who were deficient in this nutrient were 14 times more likely to develop severe or critical disease than those with higher levels.
The authors point out that adequate vitamin D levels are essential for healthy immune function.
Here is how they introduce their publication:
“Vitamin D is most often recognized for its role in bone health, but a low vitamin D status has been associated with a range of autoimmune, cardiovascular, and infectious diseases due to its role as an essential immunologic mediator.”
“Consistent with laboratory data, clinical studies have established an association between low 25-hydroxyvitamin D (25(OH)D) levels and an increased risk of acquiring influenza and respiratory viruses. Meta-analyses of randomized controlled trials conducted between 2007 and 2020 suggest that vitamin D supplementation reduced the risk of acute respiratory infection as compared with placebos.”
The Israeli data leads to this conclusion:
“In this retrospective single-institution study, we demonstrate a correlation between insufficient 25-hydroxyvitamin D (25(OH)D) level prior to COVID-19 infection and increased COVID-19 disease severity and mortality during hospitalization.”
Iranian Research:
A study published in PLOS ONE (Sept. 25, 2020) analyzed mortality data from a Tehran hospital where COVID-19 was widespread. There were 235 patients in this analysis.
The scientists found that 9.7% of patients over 40 years of age with adequate levels of vitamin D levels died from COVID-19. In comparison, 20% of those with 25-hydroxyvitamin D levels under 30 ng/ml succumbed to the infection. Biomarkers indicating inflammation were lower in people with adequate vitamin D.
How Much Vitamin D for COVID-19 Benefit?
In this study, the authors relied upon the Endocrine Society’s Practice Guidelines of 30 ng/mL as a cutoff for vitamin D “sufficiency.” Deficiency was defined as less than 20 ng/mL. What the authors measured was 25(OH)D [25 hydroxy vitamin D] levels. This is what your typical laboratory will report when you have a blood test.
Only one third of the patients in this study were deemed vitamin D sufficient. That means that two-thirds were low in this vitamin.
How Does Vitamin D for COVID-19 Work?
One of the key authors of this research was Dr. Michael Holick. He is a professor of medicine at Boston University Medical Center. In addition, Dr. Holick is one of the world’s foremost authorities on vitamin D. He and his colleagues point out that vitamin D plays a critical role in regulating the immune system.
They also note that adequate vitamin D levels can help calm inflammation:
“Indeed, the anti-inflammatory role of 1,25(OH)2D could explain the protective role of vitamin D against immune hyper reaction and cytokine storm in a subgroup of patients with severe COVID-19. This is also consistent with the recent observation that C-reactive protein (CRP), a surrogate for vitamin D status, was associated with severity of COVID-19. They concluded that higher CRP levels associated with vitamin D deficiency were related to an increased risk for severe COVID-19.”
Dr. Holick and his collaborators also point out that people with levels of 24(OH)D above 40 ng/ml did even better (PLOS ONE, Sept. 25, 2020).
They suggest that:
“Thus a blood level of at least 40 ng/mL may be optimal for vitamin Ds immunomodulatory effect…Therefore, based on available literature and results from this study it is reasonable to recommend vitamin D supplementation, along the guidelines recommended by the Endocrine Society to achieve a blood level of 25(OH)D of at least 30 ng/mL, to children and adults to potentially reduce risk of acquiring the infection and for all COVID-19 patients especially those being admitted into the hospital.”
Another Israeli Study Supports Vitamin D for COVID-19:
A different group of Israeli researchers published related findings (medRxiv, Posted September 7, 2020). This study involved big data.
They were able to use pre-existing health records of 4.6 million people, most of whom had been tested for vitamin D in the previous decade. They also had data on more than 50,000 patients who were infected with COVID-19 and 524,000 individuals matched for sex, age and location but uninfected.
Their analysis demonstrated a highly significant correlation between vitamin D deficiency and COVID-19 infection. In Israel, vitamin D deficiency is not common in the general population, but Arabs and ultra-Orthodox Jews are more prone to this problem because of their attire.
The authors note a fascinating gender reversal anomaly:
“Moreover, the male-to-female ratio for incidence is very different in these two latter groups. In Arab communities, females were significantly more affected (1:1.5), while in ultra-orthodox communities, males were more affected (1.25:1).”
They go on to observe that:
“…individuals tend to wear traditional (gender-specific) attire, with more body surface covered than the general population. These could affect the ability of the body to absorb sunlight and produce vitamin D. Previous research has shown that vitamin D deficiency is much more prevalent in these two minorities, and severe vitamin D deficiency is endemic among Arab women.”
How Vitamin D for COVID-19 Affects Infection Rates:
“In this large population study on individuals of diverse ethnic groups, we have uncovered what appears to be a strong and significant association between low vitamin D levels and the risk of SARSCoV- 2 infection. Individuals with low baseline vitamin D levels were significantly more prone to get infected with SARS-CoV-2.”
The authors conclude:
“Results from this study suggest that populations should be urged to get more sunlight exposure in order to decrease Covid-19 risk. Oral vitamin D uptake should be encouraged, preferably in the form of drops.”
Why Drops vs. Tablets of Vitamin D for COVID-19?
The authors note that a liquid formulation of vitamin D may increase the amount of this nutrient in the mucous membranes of the mouth and throat.
They speculate that:
“High vitamin D concentration in the oropharynx [mouth and throat] might be the most important factor that prevents this initial infection and replication.”
This paper was posted to MedRxiv.org on September 7, 2020 and has not yet been peer reviewed.
The People’s Pharmacy Perspective:
There is now enough data to recommend that people maintain good levels of vitamin D for COVID-19 prevention and treatment. Dr. Holick and his colleagues report that levels of 40 ng/mL might be especially helpful against COVID-19.
A blood test for 25(OH)D [25 hydroxy vitamin D] is the only way to know what your vitamin D levels are. To achieve optimum amounts of vitamin D, many people may require at least 2,000 IUs of vitamin D daily. Some individuals might need as much as 4,000 IUs. We always suggest you check with your health care professional to determine the right dose for you and monitor vitamin D levels periodically to make sure you are near the sweet spot.
You can learn more about vitamin D in our eGuide to Vitamin D and Optimal Health. It is in our Health eGuides section of this website.
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