Inflammatory bowel diseases (IBDs), which include Crohn's disease and ulcerative colitis, are chronic immune disorders. To date, researchers have been unable to determine their etiology, but have not ruled out dietary deficiencies as potential pathogenic contributors. Patients who have IBD frequently take supplements, and it's critical for clinicians to know which complementary and alternative medicines are supported by evidence.

A multinational team of researchers makes it easy to review current evidence of supplementation in IBD, and they've published a review of all studies since 1975 in the December 2016 issue of the European Journal of Gastroenterology & Hepatology. The studies found significant support for the use of several supplements.

Curcumin, turmeric's bright yellow extract, appears to suppress cyclooxygenase-2 and attenuate IBD's inflammation. It may reduce symptoms and reduce the relapse rate when given with standard medications.  IBD patients enrolled in studies reported no adverse effects.

Although few studies have examined the effect of green tea on IBD, interest in its polyphenolic compounds is high because they seem to down-regulate the inflammatory process. These researchers believe that green tea may reduce the relapse rate, but more study is needed.

Vitamin D supplementation is of great interest because IBD's prevalence is elevated in cooler climates and lower near the equator. Studies have shown that people who have adequate vitamin D levels are less likely to develop IBD. The researchers found ample evidence that vitamin D supplementation may increase bone mineral density in IBD patients and reduce disease activity.

IBD patients, especially those who undergo ileal resections larger than 20 cm, may develop vitamin B12 deficiencies. In severe case, parenteral supplementation is needed.

Up to 60% of IBD patients have folate deficiencies and need oral supplementation. Annual folate monitoring is warranted in IBD patients.
Zinc deficiency often follows chronic or severe diarrhea, so supplementation is prudent. Select patients develop iron deficiencies and need supplements.

IBD may be linked to an imbalance or pathological response to intraluminal bacteria. Although the evidence is still conflicting, probiotics may reduce disease activity in IBD patients with pouchitis.

This review also discusses other supplements that are under investigation. Numerous food supplements may be useful in IBD; knowing which are evidence-based can help pharmacists make sound recommendations.