COVID-19: Vitamin D may be able to 'switch off' lung inflammation

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• A special form of Vitamin D — not found over the counter (OTC) — may be able to combat lung inflammation caused by immune cells, a new study suggests.
• The research shows vitamin D has a “switch-off” mechanism for inflammation, which could work in severe COVID-19.
• However, clinical trials are needed before vitamin D is adopted to treat COVID-19 or other respiratory diseases.
• The researchers warn against people taking more than the recommended amount of vitamin D in hopes of staving off COVID-19 infection.

Scientists are sharing insight into how vitamin D could help in severe COVID-19 cases by revealing how the vitamin functions to reduce hyper-inflammation caused by immune cells.

A new joint study by Purdue University and the National Institutes of Health (NIH) demonstrates how an active metabolite of vitamin D — not a form sold OTC — is involved in “switching off” inflammation in the body during infections such as COVID-19.

“Since inflammation in severe cases of COVID-19 is a key reason for morbidity and mortality, we decided to take a closer look at lung cells from COVID-19 patients,” said lead authors Dr. Behdad (Ben) Afzali, chief of the Immunoregulation Section of the NIH’s National Institute of Diabetes and Digestive and Kidney Diseases, and Dr. Majid Kazemian, assistant professor of biochemistry and computer science at Purdue University.

The study appears in the journal Nature Immunology.

As part of the study, researchers analyzed individual lung cells from eight people with COVID-19.

They found that in these cells, part of the immune response to SARS-CoV-2 — the virus that causes COVID-19 — was going into overdrive and exacerbating inflammation in the lungs.

After administering vitamin D in test-tube experiments, they observed reduced lung cell inflammation.

They then dove further into how the vitamin achieved this.

They did this by turning to T helper cells — also known as CD4+ cells — which are a type of immune cell that stimulate the “killer” T cells and other white blood cells to mount an immune response.

T cells are known to play a role in severe and dangerous cases of COVID-19 by going into overdrive and leading to an often fatal phenomenon known as a cytokine storm.

Normal vs. COVID-19 infection

The scientists found that in normal infections, Th1 cells, which are a subset of helper T cells that fights microbes within the cell, go through a pro-inflammatory phase. During this phase, the body clears the infection.

Shortly after, the system shuts down to move onto the anti-inflammatory phase.

The scientists discovered that vitamin D is key in speeding up this transition.

“We found that in healthy T cells, the activation of the inflammatory gene program coincided with the activation of a vitamin D system within these cells. We, therefore, investigated how this vitamin D system works and what it does for healthy T cells before we tried to relate it back to COVID-19,” Dr. Afzali and Dr. Kazemian told Medical News Today.

Whereas in COVID-19 infections, the scientists saw that the pro-inflammatory phase of Th1 cells did not switch off. They attributed this to either a vitamin D deficiency or an abnormality in the cell’s response to vitamin D.

“As expected, by studying which genes were ‘switched on’ in the immune cells from the lungs of eight patients, we found that their cells were in an inflammatory state,” said the co-authors.

Dr. Afzali and Dr. Kazemian said they were somewhat surprised to identify the intracellular vitamin D system.

“[T]raditionally vitamin D has been thought of as depending on the kidneys to activate it before it becomes functional. We found that T cells had a self-contained system to both fully activate and respond to vitamin D, independently of the kidneys,” they said.

The researchers hypothesized that adding a highly concentrated intravenous vitamin D metabolite to existing treatments could further help people recover from COVID-19. But they have not yet tested this theory in clinical trials.

Previous studies establish links between vitamin D’s ability to reduce the inflammation caused by T cells and the severity of COVID-19.

But the authors stress that people should not take these results as a treatment recommendation, and much more work is needed.

“[I]t’s crucially important to note that this study did not test vitamin D treatment in people but analyzed lung cells from eight people who had severe COVID-19,” said Dr. Afzali and Dr. Kazemian.

“The results, although interesting, should not be taken to indicate that vitamin D is beneficial for either the prevention or treatment of COVID-19 or that it’s a substitute for other preventive and effective means of COVID-19 prevention, including vaccines, masks, and social distancing.”

– Dr. Ben Afzali and Dr. Majid Kazemian

Dr. Donald J. Alcendor, associate professor of pathology, microbiology, and immunology at Vanderbilt University School of Medicine, said the study offered clues to a possible mechanism that will need validation on a larger scale.

“There is widespread belief among the general public that taking megadoses of vitamin D can protect you prior to or following testing positive for COVID-19. The science supporting these claims is still evolving and will require a large-scale control clinical trial going forward. Even more, the mechanism for how vitamin D affects COVID-19 is still unknown,” he said.

Dr. Alcendor said that even though vitamin D is known to have immune-modulatory functions, it does not justify its use as a protective measure against COVID-19 infection, especially if one ignores COVID-19 mitigation practices.

He warned that attempting to take higher doses of fat-soluble vitamins such as vitamin D could be problematic for some people.

“A normal diet with a daily generic multivitamin will provide you with the necessary vitamin D needed,” he said.

The study suggests that vitamin D could be a therapeutic option for COVID-19 thanks to its role in hyper-inflammation.

“This study reveals a potentially unique role that vitamin D plays in the activation of T-cell functions that regulate inflammation in COVID-19, and understanding these regulatory pathways may provide information that will lead to the development of novel therapies for the treatment of acute COVID-19,” said Dr. Alcendor.

“This key finding could lead to the development of novel therapies for multiple respiratory viruses. The potential for this study could be groundbreaking.”

– Dr. Donald Alcendor

Dr. Kazemian and Dr. Afzali maintain that we will have to wait for clinical trials for results.

“There are a number of clinical trials actively studying the potential of vitamin D as an adjunct therapy for the treatment of COVID-19. When these studies have reported in, we will have a much better idea of the therapeutic role that vitamin D could play in inflammation caused by COVID-19,” they said.

However, Dr. Alcendor said future research would need to answer a slew of questions:

“[I]s this mechanism specific to COVID-19, or is it true for other respiratory infections? If this study was performed with specimens from influenza patients, would you get a similar result? Could this key finding provide information that would lead to novel therapies for multiple respiratory viruses?”