Impact of curcumin on gut microbiome

Table 1 Pharmacological effects of curcumin

Pharmacological activity	Mechanisms/effects	Key points
Anti-inflammatory properties	Inhibition of NF-κB activation and suppression of inflammatory mediators; suppression of COX-2, LOX, and iNOS expression; modulation of pro-inflammatory cytokines (e.g., TNF-α, IL-1β, IL-6); regulation of MAPK signaling pathways; inhibition of inflammatory transcription factors	Modulates gut microbiota
Antioxidant activities	Direct scavenging of free radicals; enhancement of cellular antioxidant defenses; upregulation of Nrf2 pathway; increase in antioxidant enzyme activities (SOD, CAT, GPx); metal ion chelation	Protects against oxidative stress-induced cellular damage
Anticancer properties	Cell cycle arrest and induction of apoptosis; Inhibition of cancer cell proliferation; modulation of microRNAs; suppression of angiogenesis; regulation of cancer stem cells; interference with signaling pathways (STAT3, Wnt/β-catenin, PI3K/Akt)	Gut microbiota interaction enhances effects
Immunomodulatory effects	Regulation of T cell differentiation and function; influence on B cell response; modulation of macrophage polarization; modification of dendritic cell function; alteration of natural killer cell activity	Significant impact on gut immunity
Neuroprotective activities	Protection of the blood-brain barrier; reduction of neuroinflammation; prevention of protein aggregation; enhancement of neuroplasticity; modulation of neurotransmitter systems	Gut-brain axis plays a crucial role
Cardiovascular protection	Improvement of endothelial function; reduction of atherosclerosis; modulation of lipid metabolism; prevention of cardiac hypertrophy; protection against ischemia-reperfusion injury
Antidiabetic effects	Enhancement of insulin sensitivity; protection of β-cell function; regulation of glucose metabolism; reduction of advanced glycation end-products; amelioration of diabetic complications	Ameliorates diabetic complications
Hepatoprotective activities	Prevention of hepatic fibrosis; protection against drug-induced liver injury; reduction of hepatic steatosis; modulation of liver enzyme activities; enhancement of hepatic regeneration
Antimicrobial properties	Broad-spectrum activity against bacterial, fungal, viral, and parasitic infections	Involves modulation of gut microbiota

TNF-α: Tumor necrosis factor-alpha; IL: Interleukin.

Table 2 Altered bacterial species in the gut due to curcumin

Bacterial species altered	Ref.
Escherichia-Shigella, Lachnoclostridium, Lactobacillaceae spp.	[27]
Clostridium, Bacteroides, Parabacteroides, Collinsella, Kluyvera, Enterococcus spp., Blautia spp., Ruminococcus spp.	[7]
Butyrate-producing bacteria, Clostridium, Bacteroides spp., Beneficial gut microbiota	[17]
Blautia spp. MRG-PMF1	[20]
Lactobacilli, Clostridium perfringens, Anaerobic bacteria producing butyric acid	[18]
Akkermansia, Firmicutes/Bacteroidetes ratio	[6]

Table 3 Mechanisms of action of curcumin

Mechanism of action	Ref.
Regulation of Th17/Treg balance	[30]
Modulation of microbial diversity and abundance	[30]
Improvement of gut microbiota composition	[30]
Influence on immune modulation	[29,50]
Restoration of gut flora balance	[17,29,34,35,50]
Enhancement of cytarabine response in acute myeloid leukemia	[36]
Indirect influence on neuroprotection through modulation of signaling pathways	[28,32]
Modulation of intestinal barrier function	[31]
Biotransformation by gut microbiota	[20,33,35]

Table 4 Implications of gut microbiome in gastrointestinal disorders

Gastrointestinal disorder	Curcumin's effects	Mechanisms of action	Clinical implications
Inflammatory bowel disease	Ulcerative colitis. Reduces disease activity index and endoscopic scores. Increases beneficial bacteria (Lactobacillus, Bifidobacterium). Decreases pro-inflammatory bacterial species	NF-κB pathway inhibition; Modulates Th17/Treg balance through microbiota alterations; Improves barrier function	Efficacious as adjunct therapy with mesalamine
	Crohn's disease. Reduces inflammatory markers (TNF-α, IL-1β, IL-6). Strengthens epithelial barrier integrity	Modifies intestinal microbiota composition. Influences bacterial metabolite production	Shows promise in maintaining remission
Colorectal cancer	Suppresses growth of pro-carcinogenic bacteria. Enhances production of beneficial metabolites	Alters microbial diversity in colorectal cancer microenvironment; modulates bacterial enzyme activities related to carcinogenesis	Synergistic effects with conventional chemotherapy
IBS	Reduces abdominal pain and bloating. Normalizes bowel habits	Modifies gut microbiota composition. Improves gut-brain axis signaling	Effects vary across IBS subtypes (IBS-D vs IBS-C)
Celiac disease	Reduces intestinal inflammation	Modifies intestinal permeability. Influences microbiota adaptation to gluten-free diet	Potential role in managing non-responsive celiac disease
Gastric Disorders	Helicobacter pylori infection. Modification of gastric microbiota	Direct antimicrobial effects. Enhancement of mucosal defense	Synergistic effects with standard triple therapy
	Gastric cancer. Influences Helicobacter pylori-associated dysbiosis. Affects cancer stem cell populations	Modulates inflammatory responses	Potential role in prevention and therapy
Small intestinal bacterial overgrowth	Reduces bacterial overgrowth	Modifies small intestinal microbiota composition. Improves intestinal motility	Alleviates small intestinal bacterial overgrowth-associated symptoms
Radiation-induced enteritis	Reduces oxidative stress	Preserves beneficial microbiota. Modulates inflammatory response	Maintains intestinal barrier function
Drug-induced gastrointestinal injury	Non-steroidal anti-inflammatory drugs-induced damage. Maintains microbial homeostasis	Protects against mucosal injury; Reduces oxidative stress	Enhances mucosal recovery
	Chemotherapy-induced mucositis. Preserves microbiota diversity. Reduces inflammatory damage	Supports mucosal healing	Improves treatment tolerance

IBS: Irritable bowel syndrome; TNF-α: Tumor necrosis factor-alpha; IL: Interleukin.

Table 5 Mechanism of action of gut microbiome in gastrointestinal disorders

Mechanisms of action	Description	Implications
Direct effects on gut microbiota	Selective pressure on bacterial populations: Curcumin selectively inhibits harmful bacteria while promoting the growth of beneficial microbes	Helps restore a balanced gut microbiome
	Modification of Bacterial Metabolism: Alters metabolic pathways of gut bacteria, affecting their growth and activity	May reduce production of harmful bacterial metabolites
	Influence on bacterial adhesion and biofilm formation: Disrupts bacterial adhesion to gut mucosa and inhibits biofilm formation	Reduces infection risk and persistence of pathogens
	Effects on bacterial virulence factors: Curcumin can suppress the expression of bacterial virulence factors	Lowers pathogenicity of harmful bacterial strains
Host-microbiota interactions	Modulation of immune responses: Modulates gut-associated immune cells, reducing excessive inflammatory responses	Helps in managing inflammatory bowel conditions
	Enhancement of barrier function: Strengthens the intestinal epithelial barrier, preventing translocation of pathogens	Prevents gut permeability ("leaky gut")
	Regulation of mucus production: Promotes mucus secretion in the gut, aiding in the protection of the mucosal lining	Provides an additional layer of defense against pathogens
	Influence on enterocyte function: Enhances the function of enterocytes, the absorptive cells of the intestinal lining	Improves nutrient absorption and gut health
Metabolic effects	Alteration of short-chain fatty acid production: Modulates the production of short-chain fatty acids like butyrate.	Supports gut barrier integrity and reduces inflammation
	Modification of bile acid metabolism: affects the synthesis and transformation of bile acids, impacting digestion and gut health	May alter gut microbial composition and metabolism
	Influence on tryptophan metabolism: Modifies tryptophan metabolism, affecting serotonin production and gut-brain axis signaling	Potentially improves gut-brain communication and mood
	Effects on bacterial enzyme activities: Alters the activities of bacterial enzymes involved in various metabolic processes	Influences gut homeostasis and metabolic health