Table 1.

Diseases associated with gut microbiome dysbiosis.

Disease	Microbiome change	Functional effect	Ref.
Obesity	Firmicutes/Bacteroidetes ratio ↑	Enhanced carbohydrate fermentation and nutrient absorption	[52]
	Porphyromonas, Campylobacter, Bacteroides, Staphylococcus, Parabacteroides, Dialister, Ruminococcus ↑	Associated with low microbial diversity, inflammation, and metabolic dysregulation	[53]
	Christensenellaceae, Methanobacteriales, Bifidobacteria, Akkermansia ↓	Reduced probiotics linked to inflammation and metabolic dysfunction	[54]
Type 2 Diabetes (T2D)	Firmicutes ↓ Betaproteobacteria, Lactobacillus ↑	Reduced glucose tolerance, systemic inflammation, and metabolic dysregulation	[56]
	F. prausnitzii, R. intestinalis ↓	Loss of butyrate producers linked to reduced insulin sensitivity and impaired glucose regulation	[57]
	Bifidobacterium, Bacteroides, Akkermansia ↓	Impaired gut barrier, immune dysfunction, and reduced insulin sensitivity	[58]
Inflammatory Bowel Disease (IBD)	F. prausnitzii, Bifidobacterium, Firmicutes ↓	Reduced butyrate production, impaired mucosal protection, and increased inflammation	[62]
	Clostridium leptum group, Firmicutes ↓	Reduced butyrate production and impaired mucosal immune regulation	[63]
	Bacteroides group, Bifidobacterium spp., Clostridium leptum group, Firmicutes ↓ Enterobacteria ↑	Pro-inflammatory potential and epithelial adhesion	[64]