Share on PinterestCould vitamin D be the key to rebalancing the gut, especially in people with IBD? Ekaterina Goncharova/Getty ImagesInflammatory bowel disease is a chronic condition where the body’s immune system attacks the intestines. Research is ongoing on the best ways to manage inflammatory bowel disease, including through medication and lifestyle changes. Results from a small study suggest that taking vitamin D may be helpful for people with inflammatory bowel disease and may help the body avoid attacking itself.
Inflammatory bowel disease (IBD) is a condition that “triggers the body’s immune system to mistakenly attack healthy bowel cells,” leading to symptoms such as persistent fatigue, abdominal pain, chronic diarrhea, and unexplained weight loss, according to the Centers for Disease Control and Prevention.
IBD includes the subtypes of ulcerative colitis and Crohn’s disease, and people with IBD can experience flare-ups of such symptoms intermittently.
A recent study published in Cell Reports Medicine examined how vitamin D supplementation may affect people with IBD, and found that increasing vitamin D levels may help the body’s immune system tolerate gut bacteria.
This study involved 48 adult participants who either had ulcerative colitis or Crohn’s disease and also had low vitamin D levels. Researchers collected blood and stool samples from participants at baseline and then again at the end of twelve weeks. Over these 12 weeks, participants received weekly doses of vitamin D.
Researchers evaluated a number of components, including disease activity, quality of life, and C-reactive protein in blood and stool samples. C-reactive protein can help with measuring inflammation in the body.
Researchers also focused on looking at two critical types of immunoglobins: IgA and IgG. Immunoglobulins are specific proteins produced by certain white blood cells. IgA performs several helpful functions in the digestive system, including regulating gut bacteria.
Researchers found that vitamin D had several positive effects on participants. They saw that vitamin D helped “reset” and “rebalance” the immune system’s communication with the gut microbiome. The researchers described this as promoting immune tolerance, rather than just suppressing inflammation.
Vitamin D supplementation also helped increase IgA levels, which are linked to a more stable immune response, and lower Immunoglobulin G (IgG) levels, which are linked to pro-inflammatory responses in the gut.
After 12 weeks, participants also had lower disease activity scores, meaning they felt better overall and clinically had fewer or less severe symptoms. The researchers also observed a decrease in stool-based markers of inflammation.
“The study showed that vitamin D supplementation for 12 weeks resulted in improvement of the patients as measured by disease activity scores as well as markers of inflammation. Supplementation with vitamin D resulted in significant changes in the intestinal microbial composition that were likely beneficial as well as in the gut immune system,” Steven Cohn, MD, PhD, AGAF, FACG, chief of the Division of Gastroenterology and Hepatology at the University of Texas Medical Branch, who was not involved in the study, said.
Cristiano Pagnini, MD, PhD, consultant gastroenterologist and researcher at San Giovanni Addolorata Hospital in Rome, Italy, who was also not involved in the study, explained that the findings suggest that vitamin D may influence how the immune system interacts with the gut microbiome in IBD.
“By combining microbiome and immune profiling, the authors suggest that vitamin D supplementation could shift the balance from a more inflammatory IgG-driven response toward a more tolerogenic IgA-mediated one. This is an appealing concept, as it frames IBD not just as excessive inflammation, but as a failure of immune tolerance to gut bacteria,” he told Medical News Today.
Pagnini added that the study sheds light on mechanisms of potential interactions between the vitamin D pathway and microbiota composition, which aligns with recent hypotheses of a reciprocal, synergistic effect between vitamin D supplements and probiotics.
This study was relatively small and did not provide long-term data; thus, larger, longer-term studies will likely be helpful as research moves forward.
The researchers also acknowledge that giving vitamin D wasn’t based on a randomized process or compared to a placebo.
Pagnini underscored that caution was warranted and that the study’s clinical endpoints were exploratory.
“Only serum vitamin D level is considered, while Vitamin D receptor (VDR) expression and activation are not investigated,” he said.
Pagnini also pointed out that the findings may be optimistically overinterpreted and that larger, controlled studies are needed.
“While the biological signals are strong, they do not yet translate into clear evidence of clinical benefit. As is often the case with sophisticated multi-omics research, there is a risk that mechanistic insights may be overinterpreted when applied to patient care,” he said.
John Mark Gubatan, M.D., study author, and gastroenterologist at Mayo Clinic in Jacksonville, Florida said the next steps in research would need to explain the biological mechanism behind how vitamin D behaves in the GI tract, as well as address questions such as how much vitamin D IBD patients need.
“Our exploratory study highlights [that] there could be potential benefits with vitamin D in controlling the interactions between the immune system and gut microbiome in patients with IBD and that further work is needed to understand the exact vitamin D levels and vitamin D supplementation strategies to support this in patients with IBD and other chronic inflammatory diseases,” he said.
“As a next step, we are hoping to better understand if some of the gut bacteria promoted by vitamin D could be used to directly to improve IBD and understand how this works from an immune landscape standpoint,” he continued.
“Furthermore, we hope to better understand how some of the B and T regulatory cells (immune cells that control inflammation) that migrate to the gastrointestinal tract increased by vitamin D in this study are helpful in patients with IBD,” he added.
This study suggests potential benefits of vitamin D supplementation for people with IBD.
“The implications of this study for care of patients with IBD are significant. The study suggests that vitamin D supplementation may have a role as a beneficial adjunct to current advanced therapy for this group of inflammatory bowel diseases,” Cohn said.
Cohn also noted that more research is needed before making widespread recommendations.
“Further studies of vitamin D supplementation on different disease subgroups and its interaction with specific therapeutic agents are needed to help clarify where supplementation with Vitamin D fits into current therapeutic approaches to treating patients with IBD,” he said.
Gubatan noted that current guidelines on vitamin D supplementation were based on bone health and calcium metabolism.
“Patients with chronic inflammation may have different vitamin D needs. Patients who are vitamin D-deficient should discuss supplementation with their providers and have levels rechecked as per current guidelines. It’s too early to recommend measuring gut microbiome or immune markers to test vitamin D efficacy.”
— John Mark Gubatan, MD
“In practice, these findings support what clinicians are already doing: identifying and correcting vitamin D deficiency in patients with IBD. However, it would be premature to consider vitamin D as a stand-alone therapeutic strategy,” Pagnini added.
