Table 2.
Main findings related to gut microbiota variability and composition in athletes compared to inactive controls from the selected studies.
| Author, Country, Year |
Variability | Firmicutes | Bacteroidetes | Actinobacteria | Proteobacteria | Akkermansia | Synthesis of the Results in Relation with Diet | References |
|---|---|---|---|---|---|---|---|---|
| Barton, UK, 2018 |
↑ Shannon index | ↑* (Erysipelotrichia incertae sedis) | / | / | / | ↑* | Within microbial-derived SCFAs, acetic acid, propionic acid, and butyric acid correlated with fiber and protein, while isobutyric acid, isovaleric acid, and valeric acid correlated with microbial diversity. Significant correlations for targeted measurements of SCFAs were found with Roseburia and Family XIII Incertae Sedis. | [31] |
| Clarke, USA 2014 | ↑ Shannon index ↓ Unifrac distance |
↑* Erysipelotrichia ↑* Lactobacillus ↓* Ruminococcaceae ↑* Dorea |
↑* Prevotella ↓* Bacteroides |
/ | / | ↑* | The enhanced diversity of the microbiota correlates with exercise and dietary protein consumption in the athlete group. | [33] |
| Han, China, 2020 | ↑ Shannon and Simpson index | ↑* Clostridiales ↑* Ruminococcaceae ↑* Faecalibacterium |
↓* | / | ↑* | / | Interperson microbiome variability is mainly affected by dietary factors and physical characteristics. | [36] |
| Jang, South Korea 2019 | ↔ beta diversity | ↑* Faecalibacterium ↑* Clostridium (bodybuilders) ↑* Einsenbergiella (bodybuilders) ↓* Blautia (runners) ↓* Leuconostoc (runners) ↓* Weissella (runners) |
↓* Bacteroides stercoris (bodybuilders) ↓*Bacteroides caccae (runners) |
↓* Bifidobacterium
(bodybuilders) |
↓* Parasutterella (bodybuilders) ↑* Sutterella (bodybuilders) ↑* Haemophilus (bodybuilders) ↓* Acinetobacter (bodybuilders) ↓* Enterobacter (runners) |
/ | Aerobic or resistance exercise training accompanied by an unbalanced intake of macronutrients and low intake of dietary fiber did not lead to increased diversity of gut microbiota; high-protein diets may have a negative impact on gut microbiota diversity for athletes in endurance sports who consume low carbohydrates and low dietary fiber, while athletes in resistance sports that carry out a high-protein–low-carbohydrate and high-fat diet demonstrate a decrease in SCFA-producing commensal bacteria. | [37] |
| Scheiman, USA, 2019 |
/ | ↑ Veillonella | / | / | / | / | The observed significance of the association between Veillonella relative abundance and pre- and postmarathon state is likely not confounded by any fixed effects. | [39] |
↔ no differences between groups; ↓* significant decrease; ↓ nonsignificant decrease; ↑* significant increase; ↑ nonsignificant increase.