Table 1 Alteration of microbial metabolites in Parkinson’s disease

Short chain fatty acids

 Unger, Germany [132]

34 PD, 34 controls

2.5 (1–4)

Stool

AA↓ PA↓ BA↓ VA5-

 Tan, Malaysia [125]

104 PD, 96 controls

2.2 ± 0.5

Stool

BA↓

 Aho, Finland [87]

55 PD, 56 controls

Stool

AA- PA↓ BA↓ VA-

 Pablo-Fernandez, UK [97]

35 PD, 50 controls

Stool

AA↓ PA↓ BA↓ VA↓

 Chen, Taiwan [91]

96 PD, 85 controls

2.3 ± 1.2

Stool

AA↓ PA↓ BA↓ VA-

 Yang, China [92]

95 PD, 33 controls

2.2 ± 0.7

Stool

AA↓ PA↓ BA↓ VA-

 Ahmed, India [143]

43 Drug-naïve PD, 37 controls

2.0 (1–3)

Plasma

AA↓

 Toczylowska, Poland [203]

19 PD, 21 controls

2.6 ± 0.4

Plasma

AA↑

 Zhao, China [204]

28 PD, 18 controls

Plasma

VA↓

 Shin, South Korea [134]

38 PD, 33 controls

2.0 ± 0.6

Plasma

AA↑ PA- BA-

 Wu, China [138]

50 PD, 50 controls

2.5 (0.5)

Plasma

AA- PA↓ BA↓ VA-

 Chen, Taiwan [91]

96 PD, 85 controls

2.3 ± 1.2

Plasma

AA- PA↑ BA↑ VA↑

 Kim, South Korea [137]

10 PD, 10 controls

Plasma

AA↑

 Yang, China [92]

95 PD, 33 controls

2.2 ± 0.7

Plasma

AA↑ PA3↑ BA- VA5-

 Yilmaz, USA [154]

20 PD, 20 controls

CSF

AA-

 Kumari, India [135]

76 PD, 37 controls

Saliva

AA↑ PA3↑ BA -

 Kumari, India [136]

100 PD, 50 controls

Urine

AA- BA↑

Indole derivatives

 Hatano, Japan [145]

35 PD, 15 controls

2.9 ± 1.1

Plasma

IAA↓

 Wuolikainen, Sweden [161]

22 PD, 28 controls

Plasma

indole↑

 Sankowski, Poland [160]

18 PD, 9 controls

2.9 ± 0.6

Plasma

IS-

 Shao, China [152]

223 PD, 237 controls

Plasma

ILA↓

 Rosario, German [109]

8 PD, 10 controls

Plasma

IPA↑, IS↓

 Chen, Taiwan [146]

56 PD, 43 controls

2.3 ± 1.1

Plasma

Trp- IAA- IPA↑ ILA-

 Sankowski, Poland [160]

18 PD, 9 controls

2.9 ± 0.6

CSF

IS-

 Luan, China [149]

106 PD, 104 controls

Urine

ILA↑

 Cassani, Italy [147]

68 PD, 43 drug naïve PD, 50 controls

Urine

IS↑

Bile acids

 Zhao, China [204]

28 PD, 18 controls

Plasma

GUDCA↓

 Yakhine-Diop, Spain [153]

24 PD, 8 controls

Plasma

CA↑, DCA↑, GDCA↑

 Shao, China [152]

223 PD, 237 controls

Plasma

CA↑, DCA↑, GDCA↑, TDCA↑, GDCS↑, TCAS↑, GLCAS↑

 Chen, Taiwan [146]

56 PD, 43 controls

2.3 ± 1.1

Plasma

CA-, DCA↑, GDCA↑, CDCA-, GCA-, GCDCA-, UDCA-, GUDCA-

 Yilmaz, USA [154]

20 PD, 20 controls

CSF

CA-, DCA-, GDCA-, CDCA-, GCA-, GCDCA↑, UDCA-, GUDCA- LCA-, TCA-, TCDCA-, TDCA-, TUDCA-

 Li, USA [151]

15 PD, 12 controls

Appendix

DCA↑, LCA↑

 Li, USA [151]

15 PD, 12 controls

Ileum

LCA↑

Trimethylamine N-oxide related metabolites

 Tan, Malaysia [125]

104 PD, 96 controls

2.2 ± 0.5

Stool

Choline↓ TMA↓ TMAO↓

 Ahmed, India [143]

43 Drug-naïve PD, 37 controls

2.0 (1–3)

Plasma

TMA↓

 Sankowski, Poland [160]

18 PD, 9 controls

2.9 ± 0.6

Plasma

TMAO↑

 Chen, Taiwan [158]

60 PD, 30 controls

3.2 ± 1.8

Plasma

TMAO↑

 Chung, South Korea [200]

85 drug-naïve PD, 20 controls

Plasma

TMAO↓

 Kim, South Korea [137]

10 PD, 10 controls

Plasma

TMA↓

 Sankowski, Poland [160]

18 PD, 9 controls

2.9 ± 0.6

CSF

TMAO-

 Kumari, India [135]

76 PD, 37 controls

Saliva

TMA↑ TMAO↑ Choline-

 Luan, China [149]

106 PD, 104 controls

Urine

Choline↑, TMAO↑

Hippuric acid related metabolites

 Burte, UK [165]

41 PD, 40 controls

Plasma

Catechol sulfate↓

 Okuzumi, Japan [164]

15 PRKN PD, 19 controls

2.4 ± 0.7

Plasma

HA↓ catechol sulfate↓

 Rosario, German [109]

8 PD, 10 controls

Plasma

HA↑

 Chen, Taiwan [146]

56 PD, 43 controls

2.3 ± 1.1

Plasma

HA↑

 Trivedi, UK [162]

43 PD, 21 controls

Sebum

HA↑

 Wuolikainen, Sweden [161]

22 PD, 28 controls

CSF

Benzoic acid↑