Congress of Clinical Rheumatology Annual Meeting
Congress of Clinical Rheumatology Annual Meeting
Source/Disclosures
Source:

Gershwin ME. Vitamin D and Autoimmunity. Presented at: Congress of Clinical Rheumatology-West annual symposium; October 8-11, 2020 (virtual meeting).


Disclosures: Gershwin reports no relevant financial disclosures.

October 16, 2020
2 min read
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Vitamin D holds 'more unknowns than knowns' for autoimmune diseases

Source/Disclosures
Source:

Gershwin ME. Vitamin D and Autoimmunity. Presented at: Congress of Clinical Rheumatology-West annual symposium; October 8-11, 2020 (virtual meeting).


Disclosures: Gershwin reports no relevant financial disclosures.

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Vitamin D may be just one factor in the combination of “bad genes” and “bad luck” that causes autoimmune disease, according to a presenter at the 2020 Congress of Clinical Rheumatology-West.

“There is evidence that vitamin D can affect the modulation and natural history of autoimmune diseases,” M. Eric Gershwin, MD, chief of the division of rheumatology, allergy and clinical immunology at the University of California at Davis, said in his presentation. “But just evidence, not proof.”

Photo of vitamin D pills_Shutterstock
“It is a chicken or egg,” M. Eric Gershwin, MD, told attendees. “Does vitamin D deficiency cause autoimmune disease, or does autoimmune disease, and the associated treatments and medications, cause vitamin d deficiency?” Source: Adobe Stock.

Gershwin explained why it is so difficult to make the leap from evidence to proof. “Close to 1,000 human genes interact with vitamin D,” he said. “The immune system is so promiscuous.”

Because of the myriad factors at play, it has only been in the last 10 years that the scientific community has begun to recognize that large populations of Americans are vitamin D deficient, and that this could be affecting autoimmunity.

M. Eric Gershwin

While the mechanism remains unknown, Gershwin suggested that impacts of vitamin D on Th-17 and Th-9 cells involved in adaptive immunity may be at play. In addition, vitamin D deficiency may inhibit memory B cell formation.

But Gershwin acknowledged that the etiology of many autoimmune diseases is multifactorial and some combination of “bad genes and bad luck” that is not necessarily clear to the rheumatology community. “Vitamin D is just one factor that can help shape your immune system buried somewhere in this,” he said.

All of this raises questions about how much vitamin D is optimal, or necessary, for immune health. “The reality is that every individual has different vitamin D characteristics,” Gershwin said.

While Gershwin qualified his assessment with the adage that if you put 10 different doctors in a room, you will get 10 different opinions, he suggested that recommended doses range from 400 to 1,000 international units for infants, 600 to 1,000 IUs for adolescents and up to 2,000 IUs for adults. “Statistics show that in modern life, people find it difficult to get enough vitamin D,” he said.

To that point, Gershwin noted that “anywhere between one in five and two in five of Americans are immune deficient.”

Looking at specific conditions, lower vitamin D levels have been associated with severe disease or relapse in multiple sclerosis, according to Gershwin. “But this is only seen in white patients,” he said.

At this point, Gershwin strongly highlighted that additional vitamin D has “not been shown to have any therapeutic effects” in MS.

For patients with SLE who “stay out of the sun anyway,” the data associating any therapeutic benefit of vitamin D are “not as strong” as in MS, according to Gershwin.

Similarly, increased intake of vitamin D has not been shown to be clinically efficacious in rheumatoid arthritis (RA), according to Gershwin. “Some data are out there, but I am being very cautious,” he said. “There are scoundrels out there that make a very good living on our sick patients.”

Ultimately, data investigating everything from potential therapeutic benefits to genetic associations between vitamin D and autoimmunity have led to a “rabbit hole of conflicting results,” Gershwin said. “It is a chicken or egg. Does vitamin D deficiency cause autoimmune disease, or does autoimmune disease, and the associated treatments and medications, cause vitamin d deficiency?”

Overall, Gershwin suggested that there are “more unknowns than knowns” in this space.