1. Short-term indigo naturalis therapy demonstrated symptomatic improvement in patients with mild to moderate ulcerative colitis.
Evidence Rating Level: 1 (Excellent)
Treatment options for ulcerative colitis (UC), an inflammatory bowel disease affecting the colon and rectum, are diverse, with the addition of biologics to conventional treatment in recent years. However, patients with intolerances or unable to achieve remission with conventional treatment may consider alternatives such as natural products, which have poorly documented effects on efficacy and safety. Indigo naturalis (IN) is a blue pigment from plants such as Assam indigo, false indigo, and woad. Traditionally used as an anti-inflammatory agent in Chinese herbal medicines, they are also found in enema treatments for UC patients. In this Japanese multicentre, double-blind, randomized controlled trial, 46 patients with mild to moderate UC activity (Lichtiger index 5-10) who were intolerant of or refractory to existing treatments were randomized to receive either 5 capsules (=500mg) twice a day of either IN or placebo for 2 weeks. Only two patients from the IN group had received prior treatment with biologics and patients who received recent UC intervention or increased 5-ASA or steroid use were excluded. At baseline, the IN group had a higher mean Lichtiger index (9.04 vs 7.47). After administration, the mean Lichtiger index in the IN group had significantly improved (9.04+1.92 to 4.48+2.21, p=0.01) and was significantly lower than that of the placebo group (p=0.0019), which showed no change. In terms of adverse events, 5 patients from the IN group experienced mild headaches, which was not significantly different from placebo (vs 1 patient from the placebo group, p=0.141). As well, liver enzymes in the IN group were significantly elevated but were all within normal ranges. No severe adverse events, such as pulmonary arterial hypertension or intussusception, were reported at 24 weeks. While this study showed significant improvement on a symptomatic scale after two weeks of IN administration for UC, longer trials are needed to study its efficacy and safety, which could allow for endoscopic evaluation of disease remission.
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