In a new study published in Clinical Gastroenterology and Hepatology, researchers have found that in patients with inflammatory bowel diseases, low vitamin D levels may increase the risk for certain cancers.
Inflammatory bowel diseases (IBD), which include Crohn’s disease and ulcerative colitis, are autoimmune diseases in which the immune system mistakenly attacks cells in the gastrointestinal tract, causing inflammation.
Research continues to support a role for vitamin D in IBD. One recent study found that vitamin D status may relate to disease severity and activity among patients with IBD.
Furthermore, evidence suggests that vitamin D may play a role in cancer through its ability to bind to cancer cells and help give them instructions to die, stop multiplying and spreading or stop growing.
Since vitamin D has been shown to be involved in both IBD and cancer, might it be associated with the risk of cancer in those with IBD?
Researchers recently conducted a study to find out if such an association exists. The researchers of this study were part of the same research team that, in a previous study from last year, found that IBD patients who maintained higher vitamin D levels had a decreased risk of IBD-related hospitalization and surgery.
In the current study, the researchers gathered data from a cohort that the team had previously established. This cohort includes the electronic medical records of 11,028 patients with IBD from two major medical centers in Boston.
The researchers looked at 2,809 patients with IBD from their original cohort who had at least one available measurement of their vitamin D status. Over a median follow-up time of 11 years, the researchers collected data on the development of any cancers, excluding non-melanoma skin cancers.
After the researchers collected and analyzed all of the data, here is what they found:
- The median vitamin D level was 26 ng/ml and 60.2% of the cohort had levels below 30 ng/ml.
- Over the course of the follow-up period, 7% of the cohort developed cancer.
- Ten percent of the patients with vitamin D levels below 20 ng/ml developed cancer, compared to 4% of the patients with vitamin D levels at or above 30 ng/ml (P < 0.001).
- Every 1 ng/ml increase in vitamin D status was related to a 3% reduced risk of non-metastatic cancer (P < 0.05) and a 2% reduced risk of metastatic cancer (P < 0.05).
- Vitamin D levels were most strongly related to colorectal cancer where every 1 ng/ml increase in vitamin D was related to a 6% reduced risk (P = 0.01).
- There was also a strong relationship between vitamin D status and lung cancer where every 1 ng/ml increase in vitamin D was related to a 5% reduced risk (P = 0.02).
The researchers concluded,
“The main findings from our study suggest that, in addition to its association with disease activity, low vitamin D levels in patients with IBD may also contribute to an increased risk of malignancy, particularly that of colorectal cancer. This provides further evidence supporting the incorporation of the routine assessment of vitamin D status in the care of IBD patients with appropriate treatment to prevent long-term complications.”
The researchers did not have information on certain factors that may impact their results. For example, they didn’t have information on other cancer risk factors such as smoking habits or body mass index. Furthermore, the collection of data from two medical centers in the same city means that their results may not apply to other populations. Finally, the observational design of this study means that we cannot say for sure if low vitamin D levels cause cancer in patients with IBD.
The research presented in this study provide interesting evidence for vitamin D’s role in IBD. This may be the first study to show that low vitamin D levels increase the risk of cancer specifically in patients with IBD. It is interesting that the strongest relationship was seen with colorectal cancer, a form of cancer that occurs in a similar area as that affected by IBD.
The relationship between vitamin D and cancer, specifically colorectal cancer, in patients with IBD should be explored in future trials using vitamin D supplementation. This will help clarify the relationship suggested in this study and help determine if there is a unique mechanism underlying the relationship between vitamin D and colorectal cancer in patients with IBD.
Ananthakrishnan, A. N. et al. Association Between Reduced Plasma 25-Hydroxy Vitamin D and Increased Risk of Cancer in Patients with Inflammatory Bowel Diseases. Clinical Gastroenterology and Hepatology, 2014.