Throughout the pandemic, evidence that having adequate vitamin D levels might lower a person's risk of COVID-19 has continued to mount. For example, one study involving nearly 8,300 adults enrolled in the UK Biobank study found that those who took vitamin D regularly (daily or weekly) were 34 percent less likely to develop COVID-19 compared to those who did not take vitamin D. This effect was exclusive to supplementation with vitamin D, not other supplements, suggesting a link to vitamin D specifically. Other studies have shown that...
· COVID-19 patients who had higher vitamin D levels were 20 times less likely to have a critical outcome versus a mild one, and 8 times less likely to have a severe outcome versus a mild one.
· Among patients with COVID-19, 98.9 percent of those with vitamin D deficiency died; 88 percent of those with vitamin D insufficiency died; and just 4 percent of those with sufficiency died, even after adjusting for age, gender, and comorbidities.
What's driving the protective connection between vitamin D and COVID-19?
Many things. But one, in particular, stands out: regulation of the renin-angiotensin system. A key player in this system is ACE2, a protein found on the surface of many cells in the body. You might already know that ACE2 serves as the SARS-CoV-2 entry point into our cells. But ACE2 is critical for the conversion of angiotensin II to angiotensin 1-7, a process that helps regulate blood pressure and fluid balance in the body and is linked to immune health and protection from COVID-19, as we show in this figure:
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Here's how it works.
Angiotensin II is a vasoconstrictor, but it also promotes inflammation and oxidative stress. In a good enzyme/bad enzyme scenario, angiotensin 1-7 keeps angiotensin II in check, but only when a balance between the two enzymes is maintained.
Unfortunately, when SARS-CoV-2 binds to the ACE2 protein to gain entry into cells, it takes the ACE2 protein into the cell with it, impairing ACE2 function and perturbing the balance between angiotensin II and angiotensin 1-7. Ultimately, this promotes inflammation and can trigger acute respiratory distress syndrome (ARDS), the primary cause of death from COVID-19.
Vitamin D may prevent ARDS
Vitamin D blocks the production of renin and angiotensin II and stimulates expression of ACE2. The end result: greater conversion of angiotensin II to angiotensin 1-7 and protection from ARDS.
How much vitamin D do we need for protection against COVID-19?
The vitamin D "sweet spot" may be 50 ng/ml
A recent study analyzed data from a population-based study measuring long-term vitamin D status in more than 400 million people worldwide, as well as seven clinical studies measuring vitamin D levels post-infection. The result? People who had vitamin D levels of 50 nanograms per milliliter (ng/ml) or higher preceding SARS-CoV-2 infection were extremely unlikely to die from their illness, suggesting that vitamin D may reduce the risk of death from COVID-19 – theoretically to a level of ZERO.
The 50 ng/ml figure aligns with the classifications established by the Endocrine Society:
· Insufficiency: 21 to 29 ng/ml
· Deficiency: less than 20 ng/ml
Based on these classifications, approximately 70 percent of people living in the United States have vitamin D insufficiency and 40 percent have deficiency – disturbing figures in light of vitamin D's importance in human health.
Why not treat COVID-19 patients with vitamin D?
A variety of interventional studies have popped up, asking this very question. Of course, one problem with this approach is that it's possible that by the time a person has COVID-19, supplementation may be "too little, too late," since vitamin D typically takes a long time to exhibit broad systemic effects.
Nevertheless, one study put this to the test in 40 adults who had a positive SARS-CoV-2 RNA test, mild or no COVID-19 symptoms, and vitamin D deficiency. The investigators assigned 16 study participants to take 60,000 international units of vitamin D3 orally until they reached a blood level greater than 50 ng/ml.
After two weeks of supplementation, 75 percent of the participants achieved a vitamin D blood level greater than 50 ng/ml. Those who corrected their deficiency were more likely to clear the virus by day 21 of the study. They also experienced a decrease in serum fibrinogen, a marker of inflammation.
Bottom line? Public health measures such as getting vaccinated, wearing masks indoors in high-risk areas, maintaining social distance, and washing hands are crucial for reducing your risk of getting COVID-19. Robust evidence suggests that maintaining healthy vitamin D status can play a role, too.
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Thanks for reading!
Rhonda and team
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