Table 2.

Gut microbiota associated with nine common skin disorders.

Disease	Associated Gut Microbiota	Additional Remarks	Reference
1. Acne vulgaris	Decrease in Firmicutes and increase in Bacteroides.	Distinct gut microbiome composition and decreased diversity.	[106]
2. Atopic Dermatitis	Higher levels of Faecalibacterium prausnitzii, Clostridium, and Escherichia (in infants). Lower levels of Akkermansia, Bacteroidetes, and Bifidobacterium.	Probiotics consumption can prevent AD *.	[107,108,109,110,111,112,113,114]
3. Psoriasis	Changes in $\beta$-diversity. Gut microbiome changes in reaction to biologicals.	Increased risk of intestinal immune disorders. Diet and gut microbiome can have an impact on inflammation.	[115,116,117,118,119,120]
4. Hidradenitis suppurativa	Unknown	Increased risk in developing CD * and UC *.	[121,122]
5. Rosacea	Can be associated with SIBO *. Acidaminococcus and Megasphaera increase and Peptococcaceae and Methanobrevibacter decrease.	Can be associated with H. pylori infection.	[123,124,125]
6. Dandruff and Seborrheic dermatitis	Unclear	Probiotic consumption can alleviate moderate to severe dandruff	[126]
7. Alopecia areata	No major differences	FMT * in 2 patients showed restoration of hair growth	[127,128]
8. Skin cancer	Not reported	Other cancers are associated with microbial dysbiosis	[129,130,131]
9. Wound healing	Not reported	Not reported

* Abbreviations: atopic dermatitis (AD), Crohn’s disease (CD), fecal microbiota transplant (FMT), hidradenitis suppurativa (HS), small intestinal bacterial overgrowth (SIBO), and ulcerative colitis (UC).