Reishi mushroom (Ganoderma lucidum) has a long history of use in traditional medicine, primarily in East Asia, for general immune support and as a tonic. More recently, scientific research has explored its potential in managing inflammatory conditions, including colitis. Several preclinical studies (using animal models) have shown that extracts from Reishi can reduce inflammation in the colon, improve histological markers, and modulate immune responses associated with colitis. The proposed mechanisms include inhibition of pro-inflammatory cytokines (such as TNF-α and IL-6), reduction of oxidative stress, and modulation of gut microbiota.

Despite these promising results in animals, there is currently a lack of robust clinical trials in humans to confirm efficacy or establish safety for people with colitis, including ulcerative colitis or Crohn's disease. Most human evidence is limited to case reports or studies on general immune health, not specifically on colitis. As such, the scientific evidence supporting Reishi's use for colitis is preliminary and primarily based on animal studies, not high-quality human data. Therefore, while the use of Reishi for colitis has some scientific backing at the preclinical level, it should be considered experimental, and patients should consult healthcare professionals before use.