TABLE 1.
Factors influencing the gut microbiota.
| Factors | Diseases | Results | References |
|---|---|---|---|
| Diet | |||
| Modified Mediterranean‐ketogenic diet (MMKD) | AD | Causes changes in gut bacteria and organic acids that correlate with AD cerebrospinal fluid (CSF) biomarkers | 32 |
| MCI | The γ‐aminobutyric acid (GABA) is regulated in MCI patients. | 33 | |
| Vegetarian diet | PD | PD‐associated microbiome changes occurred, Unified Parkinson's Disease Rating Scale Part III scores improved significantly, and levodopa equivalent daily dose decreased. | 34 |
| Mediterranean diet | PD | Roseburia abundance of PD patients is reduced, and constipation symptoms improve. | 35 |
| Processed food | ADHD | The processed food and ADHD groups showed significantly lower α‐diversity of gut microbiota than the control group. | 36 |
| Genetics | |||
| AD | The host genetic factors influencing the abundance of ten genera are significantly associated with AD. | 37 | |
| PD | Genetically increased Bifidobacterium levels correlated with decreased PD risk. | 38 | |
| ASD | The genera Prevotellaceae and Turicibacter predicted by genetic analysis may be positively associated with ASD. And genera Dorea, Ruminiclostridium5, Ruminococcus1 genera and Sutterella for ASD potentially protective role of the gut microbiota. | 39 | |
| Depression | Increased abundance of Morganella and Klebsiella has been causally associated with depression. | 40 | |
| Environment | |||
| Smoke | AD | Prevotella abundance was negatively correlated with smoking. | 41 |
| PD | Smoking was associated with β‐diversity. | 42 | |
| Geographic location | PD | Comparable findings to previous studies from the Northern hemisphere in regard to changes in gut microbiota composition | 43 |
| ASD | The gut microbiome in individuals with ASD is affected by study‐site location as well as gastrointestinal symptom severity. | 44 | |
| PM10 or NO2 | ASD | PM10 and possibly NO2 exposure during early pregnancy may affect autistic traits at age 6 years through the alteration of Proteobacteria abundance. | 45 |
| As and Hg | ASD | Arsenic and mercury were significantly associated with Parabacteroides and Oscillospira in the gut. | 46 |
| Ethnicity | Depression | The gut microbiota is linked to depressive symptom levels and that this association generalizes across ethnic groups. | 47 |
Abbreviations: CSF, cerebrospinal fluid; MCI, mild cognitive impairment; MMKD, modified Mediterranean‐ketogenic diet; γ‐aminobutyric acid, GABA.