When you think of vitamin D, soaking up some sunlight may come to mind. But for 30-40% of people with IBD, there’s a deficiency. I’m one of those people. Despite taking a daily dose of vitamin D in pill form, I’m still well below the “normal” range. My GI recently had me go from taking 2,000 IU a day, to 50,000 IU two times month.

The role of vitamin D with disease activity and inflammation

According to Dr. David Rubin, Chief of Gastroenterology, Hepatology and Nutrition at the University of Chicago, “We know that the lower the vitamin D, the more inflammation people have. There is even a “sunlight gradient” in parts of the world where Crohn’s disease is more or less prevalent based on exposure to sunlight- suggesting that more sunlight (and more of that kind of vitamin D) may be preventive or conversely, that less sunlight may be a risk factor.”

While it’s unclear why vitamin D deficiency is so common in the IBD population, Dr. Rubin says, “We definitely know it’s lower in IBD folks than others who live in the same geographic areas and who are the same age. We suspect there may be an activated inflammatory pathway that is a result of the IBD OR that the deficiency is due to a mutation in the Vitamin D receptor that prevents adequate uptake.”

He went on to say it’s not so much a malabsorption issue, as some assume. Therefore, it’s important those with IBD know what their vitamin D level is, even if they feel well and are in remission.

The importance of measuring vitamin D levels 

Severe vitamin D deficiency over time can result in bone loss, delayed or impaired wound healing (and this includes the “wounds” in your bowel), depression, and fatigue. All symptoms and conditions that can occur in IBD! So, knowing your vitamin D and addressing deficiencies is very important. Vitamin D aids in calcium and phosphorus absorption, which is necessary for healthy bone turnover and growth.

“An interesting study at Digestive Disease Week a couple years ago looked at treating low vitamin D in active ulcerative colitis. Of the patients who had a response and normalized their vitamin D levels, they also had improvement in their ulcerative colitis. It was a well-done proof-of-principle study but very important and suggests that this may be a novel treatment in the future, or even be an adjuvant therapy. The key was that patients had to get their Vit D >40 ng/mL,” said Dr. Rubin.

When I had my vitamin D measured this past month, I was at 22 ng/mL, despite taking daily vitamin D and being in clinical remission. As an IBD patient of nearly 15 years, I’m interested to see if shifting to the 50,000 IU capsule of Vitamin D twice a month will help put me in the “normal” range. Time will tell!

It’s recommended that IBD patients get vitamin D levels measured in their blood work at least once a year. If the number is low, then Dr. Rubin recommends repeating labs more often after supplementation has started. While sunlight can certainly increase Vitamin D, it doesn’t seem to be sufficient enough to address the deficiency in patients with IBD-related low levels.