Inflammatory bowel disease – the one thing vitamin D and bacteria may have in common

Posted on: May 4, 2018   by  Riley Peterson & John Cannell, MD.


Did you know, the communities of bacteria that live in your gut, often referred to as the microbiota, create a signature that is more unique than your fingerprint? Billions of tiny organisms, both good and bad, live within your digestive tract! Though the role this plays in the body is still mostly unknown, many believe the microbiota has a significant impact on one’s overall state of health.

There are countless combinations of the thousands of bacterial colonies that can live within the gut. According to research, there are certain species and combinations of species that are found common in healthy individuals.

So, how can gut microbiota affect me?

Age, diet, environment, genes and medications are important factors that might affect the microbiota. In turn, the microbiota plays a role in certain health conditions. Research has found a possible role of microbiota in several health conditions. This includes cancer, heart health, and immune diseases such as rheumatoid arthritis and inflammatory bowel disease (IBD).

For example, gut bacteria are thought to trigger an inflammatory response in the protective mucosal lining of the digestive system in individuals with IBD such as Crohn’s disease (CD) and ulcerative colitis (UC). This inflammatory response can lead to pain and cramping in the abdomen, bloating, reduced appetite and weight loss. Additionally, it can become more severe if left unmanaged.

Managing gut health and inflammation

Unless you’re living with IBD or another autoimmune condition, most of us probably won’t be able to tell whether or not our gut bacteria is well-balanced or healthy. So, whether you have struggled with UC or might just feel indigestion every so often, what can we do to promote better microbiota health?

Managing your diet is the most effective way of promoting a healthy gut microbiota. This can include avoiding foods that tend to upset your stomach. You can also increase your intake of fermented foods, prebiotics (good bacteria) and probiotics (bacteria food). Another important addition, as suggested by recent research, could be daily vitamin D supplementation.

Past studies have indicated vitamin D plays a role in both regulation of the immune system and management of the inflammatory response. These two functions of the body are thought to be closely related to both microbiota balance and inflammatory bowel disease. In fact, vitamin D levels are thought to be associated with Crohn’s disease and ulcerative colitis remission and disease outcome.

However, researchers and scientists don’t know how vitamin D status influences our gut microbiota, and how this might affect the symptoms of IBD. Therefore, researchers recently conducted a study to evaluate this relationship.

Vitamin D research: the effect of supplementation on the microbiota and Crohn’s disease

In a recent study, researchers compared the effect of vitamin D supplementation on both healthy participants and those with CD. Seven patients with CD and vitamin D deficiency and seven healthy patients with vitamin D deficiency from the Outpatient Clinic of the University Medical Center Rostock were included in this study. All participants were supplemented with 20,000 IU vitamin D3 daily for three days, and then every other day for the rest of a four-week period.

Vitamin D levels were checked at baseline and then weekly for the rest of the study. Stool samples were also collected weekly to study the bacterial microbiota of each participant. Last, in those with CD, the Crohn’s Disease Activity Index (CDAI) was used to assess disease severity, with higher scores indicating more severe symptoms.

Unsurprisingly, vitamin D supplementation was associated with an improvement in vitamin D statusfrom about 16 ng/ml (40 nmol/l) to about 57 ng/ml (143 nmol/l) at four weeks. Though insignificant, vitamin D supplementation was also associated with improved CD symptom severity. It is important to note that while this was not a significant relationship, there were very few patients to test, and more subjects taking vitamin D for a longer time has shown treatment effects.

As for the effect of vitamin D supplementation on the bacterial microbiota, there were some unexpected findings. Interestingly, the researchers discovered that supplementation in those with CD, but not the healthy controls, accumulated specific strains of bacteria in larger numbers. Additionally, there was an observed shift in bacterial composition at week one; however, this change was reversed in following weeks. Lastly, the researchers discovered that in those with CD, bacterial diversity decreased over time. Greater diversity is typically recognized as beneficial, especially in those with IBD. However,the researchers theorized that this could have been due to the brief period of supplementation, and longer trials could have altered these findings.

What could this mean?

Almost always, research aimed to answer questions just generates more questions. This study is no different and presented some conflicting findings. However, the researchers who conducted this study believe that these findings are an important first step in a field in which little is known. Overall, this study suggests that vitamin D status may play a role in the pathogenesis, or development, of CD.

The researchers concluded,

“…vitamin D administration may be an important additional therapeutic intervention in the management of CD.”

But, what does this mean for me?

Overall, research shows that vitamin D plays a role in health and wellness from your head down to your toes. If you have Crohn’s disease or ulcerative colitis, it might be especially important for you to keep a healthy vitamin D status, between 40-80 ng/ml (100-200 nmol/l).

However, even for healthy individuals, vitamin D is important for many aspects of heath. To stay within a healthy range, the Vitamin D Council recommends supplementing between 5,000 – 10,000 IU (125-250 mcg) vitamin D3 per day.

Not sure what might be right for you? That is what the Vitamin D Council is here for! Email us your questions at


Peterson, R. & Cannell, JJ. Inflammatory bowel disease – the one thing vitamin D and bacteria might have in common. The Vitamin D Council Blog & Newsletter, 2018.