TABLE 1.

Methods used for assessing the microbiome and outcomes of the studies discussed in this review (in alphabetical order).

First author	Method	Main findings in patients with functional dyspepsia compared to healthy subjects
Fukui et al., 2020	16S-rRNA sequencing, Primer: 341F, 805R	Firmicutes ↑, Streptococcus ↑
Igarashi et al., 2017	16S-rRNA sequencing, Primer: 341F, 806R	Acidobacteria ↓, Bacteroidetes > Proteobacteria ↑
Nakae et al., 2016	16S-rRNA sequencing, Primer: 516F, 1510R	Bifidobacterium ↑, Prevotella ↓
Qiu et al., 2017	16S-rRNA sequencing, Primer: 515F, 806R	Bacteroidetes ↓, Cyanobacteria ↑, Firmicutes ↑, Proteobacteria ↑
Vasapolli et al., 2021	16S-rRNA sequencing, Primer: not indicated	no differences
Zhong et al., 2017	16S-rRNA sequencing, Primer: 917F, 1392R	Actinomyces ↓, Prevotella ↓, Streptococcus ↑, Veillonella ↓

↑, increased; ↓, decreased.