摘要：Whether the gut microbiome in obesity is characterized by lower diversity and altered composition at the phylum or genus level may be more accurately investigated using high-throughput sequencing technologies. We conducted a systematic review in PubMed and Embase including 32 cross-sectional studies assessing the gut microbiome composition by high-throughput sequencing in obese and non-obese adults. A significantly lower alpha diversity (Shannon index) in obese versus non-obese adults was observed in nine out of 22 studies, and meta-analysis of seven studies revealed a non-significant mean difference (−0.06, 95% CI −0.24, 0.12,
I
2
= 81%). At the phylum level, significantly more Firmicutes and fewer Bacteroidetes in obese versus non-obese adults were observed in six out of seventeen, and in four out of eighteen studies, respectively. Meta-analyses of six studies revealed significantly higher Firmicutes (5.50, 95% 0.27, 10.73,
I
2
= 81%) and non-significantly lower Bacteroidetes (−4.79, 95% CI −10.77, 1.20,
I
2
= 86%). At the genus level, lower relative proportions of
Bifidobacterium and
Eggerthella and higher
Acidaminococcus,
Anaerococcus,
Catenibacterium,
Dialister,
Dorea,
Escherichia-Shigella,
Eubacterium,
Fusobacterium,
Megasphera,
Prevotella,
Roseburia,
Streptococcus, and
Sutterella were found in obese versus non-obese adults. Although a proportion of studies found lower diversity and differences in gut microbiome composition in obese versus non-obese adults, the observed heterogeneity across studies precludes clear answers.
