The alga Euglena gracilis stimulates Faecalibacterium in the gut and contributes to increased defecation - PubMed (original) (raw)

The alga Euglena gracilis stimulates Faecalibacterium in the gut and contributes to increased defecation

Ayaka Nakashima et al. Sci Rep. 2021.

Abstract

The alga Euglena gracilis (E. gracilis) has recently gained attention as a health food, but its effects on human gut microbiota remain unknown. This study aimed to determine the effect of E. gracilis on gut microbiota and defecation due to modulation of microbiota composition in vitro and in vivo. The in vitro model simulating human colonic microbiota revealed that E. gracilis addition stimulated the growth of commensal Faecalibacterium. Further, E. gracilis addition enhanced butyrate production by Faecalibacterium prausnitzii. Paramylon, an insoluble dietary fibre that accumulates in E. gracilis and is the main component of E. gracilis, did not stimulate Faecalibacterium growth in vitro. Daily ingestion of 2 g of E. gracilis for 30 days increased bowel movement frequency as well as stool volume in 28 human participants. Collectively, these findings indicate that E. gracilis components other than paramylon, stimulate the growth of Faecalibacterium to improve digestive health as well as promote defecation by increasing butyrate production.

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Conflict of interest statement

AN, KY, and KS are employees of euglena Co., Ltd. All other authors declare no competing interests.

Figures

Figure 1

Figure 1

Euglena gracilis addition changes microbiota composition. (a) Genus-level compositional view of bacteria in the original faecal samples (Faeces), in vitro human colonic microbiota models (Control), models with E. gracilis (+ Euglena), and models with paramylon (+ Paramylon) after 48 h of fermentation. The means of 11 samples from healthy human subjects are shown. Genera of lower abundance (< 1.0%) and lower similarity (< 97%) were included in Others and Unclassified Bacteria, respectively. (b) Box-and-whisker plots representing relative abundances of bacteria related to Faecalibacterium. **P < 0.01, n = 11, Wilcoxon signed rank test. Circles outside the whiskers represent outlier samples.

Figure 2

Figure 2

Euglena gracilis addition enhanced butyrate concentrations. Production of (a) butyrate, (b) acetate, (c) propionate, and (d) short-chain fatty acids (SCFAs) (sum of lactate, succinate, acetate, propionate, and butyrate) in in vitro human colonic microbiota models (Control), models with E. gracilis (+ Euglena), and models with paramylon (+ Paramylon) after 48 h fermentation. **P < 0.01, n = 11, Wilcoxon signed rank test.

Figure 3

Figure 3

(a) Cells detected by real-time PCR and (b) concentration of butyrate produced by Faecalibacterium prausnitzii without Euglena gracilis (Control) and with E. gracilis addition (+ Euglena) after 72 h of cultivation. *P < 0.05, **P < 0.01, n = 3, two-tailed Student’s _t_-test.

Figure 4

Figure 4

Euglena gracilis ingestion increases the proportion of the Faecalibacterium genus in the gut flora. (a) Genus-level compositional view of bacteria in human faecal samples after 0, 14, and 30 days of E. gracilis ingestion. (b) The relative abundances of the Faecalibacterium genus. *P < 0.05, n = 28, Wilcoxon signed rank test.

Figure 5

Figure 5

Euglena gracilis ingestion promotes defecation. (a) The frequency of defecation per day and (b) the volume of defecation per stool. One defecation volume is equivalent to one medium-sized chicken egg (about 60 g). Mean ± SEM, **P < 0.01, n = 28, Wilcoxon signed rank test.

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