Table 3 Altered gut microbial metabolites in patients with PD
From: Parkinson’s disease and gut microbiota: from clinical to mechanistic and therapeutic studies
Ref. | Sample size | Sample | Control factors | Dietary instruments | Technique | Findings |
|---|---|---|---|---|---|---|
[101] | PD: 34 Healthy: 34 | Fecal | Age-matched; no special dietary habits | Dietary habits were interviewed | Gas chromatography | PD is associated with certain gut microbiota and reduced fecal SCFAs |
[93] | PD: 75 Healthy: 50 | Serum | Aged 40–85 years, onset age 40–80 years, disease duration ≤ 12 years; age-matched; medications, diet, and demographics collected | FFQ | UPLC-MS; HILIC-MS | The microbiota of PD had decreased carbohydrate fermentation and butyrate synthesis and enhanced proteolytic fermentation and p-cresol and phenylacetylglutamine production. Patients with constipation and stool consistency had more proteolytic metabolites and taxonomic changes |
[206] | PD-MCI: 13 PD-NC: 14 Healthy: 13 | Fecal | Spouses as control; age-matched; BMI-matched; no serious chronic illnesses (e.g., hyperlipidemia, diabetes); no fat-rich diet | Questionnaire including caffeine and alcohol intake | GC–MS | SCFAs were similar in PD-MCI, PD-NC, and healthy, however, the isovaleric and isobutyric levels negatively correlated with the MMSE scores |
[194] | PD: 64 Healthy: 51 | Fecal | Spouses or family members as control; internal medicine, neurological, or unstable psychiatric illness excluded | N.A | GC–MS | Lipids, vitamins, amino acids, and other organic compounds changed. Most modified metabolites closely associated with Lachnospiraceae abundance |
[95] | PD: 8 Control: 10 | Serum | Early, L-DOPA-naïve PD; only male; 5 healthy controls, 5 diseased controls having cardiovascular risk factors | Omnivorous vegetarian probiotics | Targeted metabolomics | Disease severity is linked to mucin and host glycans breakdown by microbes. Gut-community metabolic modeling shows that PD bacteria cause folic acid deficiency and hyperhomocysteinemia |
[96] | PD: 104 Non-PD: 96 | Fecal | 91 spouses, 5 siblings as control; diet, lifestyle and housing condition considered | FFQ | NMR; LC–MS | Neuroprotective chemicals such as SCFAs, ubiquinones, and salicylate, as well as ceramides, sphingosine, and TMAO, are linked to PD metabolite features and functional changes. Clinical signs include cognitive impairment, BMI, frailty, constipation, and physical activity are also linked to it |