Table 4.

Effect of curcumin on gut microbiota and its mechanism of action.

Curcumin Doses	Effect on Gut Microbiota	Molecular Mechanisms	Model	Ref.
Curcumin at a low dose (1 g/day)	Curcumin shifted the structure of gut microbiota	Curcumin enervated the Western diet-induced development of atherosclerosis and type 2 diabetes mellitus	Sprague Dawley rats	[225]
100 mg/kg/day	Lowers the increasing abundance of the genera Anaerotruncus and Helicobacter in the gut microbiota	Decreases the estrogen level, resulting in an increase in body weight	Wistar rats	[226]
100 mg/kg/day	Curcumin affected the presence of Prevotellaceae, Bacteroidacea, and Rikenellaceae in gut microbiota	Curcumin possesses anticancer activity in vitro and in preclinical animal models via the activation of caspases 3, 8 and 9 in the colon cancer cell lines	Fecal sample	[227]
8000 mg per day	Increase in Lactobacillus and decrease in Coriobacterales	Induction of apoptosis through the COX-2 and non-COX-2 pathways. It targets cancer stem cells (CSC) through direct or indirect influences on the CSC self-renewal pathways.	Colon cancer cell lines, SW480 and SW62	[228]
0.2% (w/w) nanoparticles of curcumin	Increase in butyrate-producing bacteria and the fecal butyrate level	Mucosal mRNA expression of inflammatory mediators and the activation of NF-κB in colonic epithelial cells were suppressed by curcumin nanoparticles	BALB/c mice	[229]