Vitamin D And COVID-19: Should You Start Supplementing?

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The buzz around vitamin D and COVID-19 is growing. What is the science behind it?  

COVID-19 can have debilitating, even fatal consequences, and older people have higher chances of dying from it. So, as you age, one thing is clear – you don't want COVID-19 in your life. Some argue the solution is as simple as a vitamin D supplement. Should you run to grab a bottle of vitamin D pills? Not before you've read this article:  

Here’s What We Know:  

As COVID-19 swept the globe, scientists faced the immense pressure of finding a cure.  

Vitamin D supplementation was one of the earliest ideas – and it made sense. It had already been used for other respiratory infections [1], plus vitamin D was known to impact human immunity. [2] 

In a world desperate for quick answers, the media latched onto early, inconclusive evidence. But I'm not here to sell you the hype. Instead, let's talk about what the actual science said:  

Deficiency Linked To Poorer Outcomes 

Multiple studies show that vitamin D deficient patients do worse when they get COVID-19. Vitamin D levels seem related to both the severity and mortality from the disease. [3] 

So low vitamin D causes bad COVID-19? Absolutely not.  

Vitamin D and COVID-19

The age-old “correlation is not causation” idea applies. Just because very sick COVID-19 patients happened to have low vitamin D levels doesn't mean it's the deficiency that caused a poor outcome.  

For example, frail people tend to spend more time indoors. Since you need UV light to synthesize vitamin D, not getting enough sun could lead to a deficiency. Now, if this frail person gets COVID-19, they're more likely to get severe symptoms than their healthy, outdoorsy neighbor. Did the vitamin D cause it? Clearly not.  

COVID-19 And Vitamin D Deficiency Risk Factors… Are The Same! 

Who gets worse COVID-19? People with chronic conditions, the elderly, or those with a suppressed immune system.  

Who is more likely to be vitamin D deficient? Those same people.  

With the research we have right now, we can’t say whether vitamin D and COVID-19 are definitively related. So, no need to supplement? Not so fast…  

The Case For Vitamin D Supplementation 

Vitamin D is essential for healthy bones, immunity, mood, and so much more. Here is how it could help in the fight against COVID-19.   

This Is What Happens In COVID-19: 

The COVID-19 infection could be as mild as a few days of low fever or as severe as pneumonia, myocarditis, thrombosis, and acute respiratory distress. What brings about these debilitating symptoms? Uncontrolled inflammation.  

Your immune system is a complex “army” that eliminates infection, but its killing methods can also injure healthy tissues. Let lose; these immune responses can cause catastrophic damage to your vital organs in the effort to eliminate the virus.  

Vitamin D and COVID-19

But, vitamin D might be able to help: 

Vitamin D And Your Immune System 

Vitamin D has a wide range of functions in your body. From protecting bone density to regulating gene expression, it’s an essential “ingredient” in multiple biochemical processes. And, it happens to have a key role in immunity and COVID-19:  

  • Regulatory lymphocytes – vitamin D is essential for T reg lymphocytes, which keep your immune response in check [4]  
  • Cytokines – these are protein signals that immune cells use to communicate. Too much pro-inflammatory cytokines and you have a cytokine storm, which causes severe COVID-19 symptoms. Vitamin D helps regulate the response and promotes anti-inflammatory cytokines instead [5].  
  • Thrombosis – unwanted blood clotting (thrombosis) is one of the worst COVID-19 complications. Vitamin D plays a role in clotting pathways, reducing thrombosis. [6]   

In short:  

Vitamin D stops a lot of the underlying mechanisms of severe COVID-19. Healthy vitamin levels make you healthier overall – and, in the case of COVID, more likely to survive the infection.  

Deficiency Is Growing  

In the United States, a whopping 41.6% of adults are vitamin D deficient [7]. We don’t get enough sunlight, especially during the winter, and that affects everything – from bone health to mood and the risk of chronic disease [8].  

Vitamin D and COVID-19

Across the pond, British health authorities are already recommending vitamin D supplementation [9] to stay healthy during the colder months. Darker skin also puts you at risk for vitamin D deficiency, so black, Latino, and ethnic minorities should consider supplementing year-round.  

Should I Start Supplementing?  

So far, so good. We explained how vitamin D affects immunity, why that is relevant to COVID-19, and also why the current research is inconclusive. But we haven’t answered one key question:  

Will A Vitamin D Supplement Help?  

If you already have COVID-19, vitamin D is unlikely to do much. Some researchers have tried this, but they've shown little to no impact. The study that did show vitamin D to improve COVID-19 was then heavily criticized for bias and hasn't been replicated.  

So, we know vitamin D will not cure your COVID-19.  

However, we also know that: 

  • Low levels have been linked to worse outcomes, even if we can’t prove the correlation.  
  • Vitamin D acts on the immune system and stops the processes behind COVID-19 complications.  
  • Deficiency is incredibly common, and staying indoors puts you at risk. In other words, more lockdowns mean less vitamin D.  

There are clear benefits of vitamin D supplementation, both for COVID-19 and other conditions. Even better, the risk is minimal as long as you stick to the recommended dose.  

Adults need 10 micrograms of vitamin D a day [9], but it’s hard to get that much from your diet. Supplements are an easy, low-risk solution – and they come with benefits for bone density, mental health, and immunity [10]. In fact, some research even suggests low vitamin D can cause premature aging, so a supplement can also help with longevity. [11] 

Final Thoughts 

COVID-19 can be a terrifying disease, especially if you’re in a risk group.  

However, there is also plenty you can do to minimize your chances of severe infection. Getting enough vitamin D is crucial to overall health, so supplementation is a great idea. Healthy vitamin D levels will also prevent bone breaks, mood disorders, and even premature aging.  

Vitamin D and COVID-19

But don't let the media hype fool you. This is a supplemental approach. Vaccination and social distancing remain the best ways to prevent the disease – so make sure you get the jab.    


Denny Pencheva
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