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An Interventional Soylent Diet Increases theBacteroidetestoFirmicutesRatio in Human Gut Microbiome Communities


Hsu, Ryan BS1; McCormick, Dylan BA2; Seitz, Mitchell Lee J. Jr. BA3; Arkin, Adam PhD2

American Journal of Gastroenterology: October 2017 - Volume 112 - Issue - p S67–S69

1University of California, Berkeley, Davis, CA;

2University of California, Berkeley, Berkeley, CA;

3University of California, Berkeley, Tracy, CA

Introduction: Our knowledge of the relationship between the gut microbiome and health has rapidly expanded in recent years. In particular, diet has been shown to affect health outcomes such as obesity and intestinal inflammation by altering microbiome composition. Among consumers seeking healthy alternatives to traditional diets, liquid-meal replacements such as Soylent 2.0 have become increasingly popular. However, the effects of these substitutes on the gut microbiome remain largely uncharacterized. This study aims to characterize the changes in gut microbiota composition resulting from a short-term Soylent 2.0 diet.

Methods: Fourteen participants were selected and separated into either the control group (n=5) or Soylent group (n=9). Participants in the control group adhered to their regular reported diets for the duration of the study, while those in the Soylent group underwent an interventional Soylent-only diet between regular diet phases (Figure 1). Subjects completed electronic daily logs reporting diet and any discomfort. Eight fecal samples per participant were collected using fecal sampling kits, which were sent for V4 16S rDNA sequencing. Reads were clustered into operational taxonomic units (OTUs) and identified against the GreenGenes 16S database.



Results: We find that an individual's within-sample diversity (α-diversity) is not significantly altered by an all-Soylent diet. In addition, principal coordinate analysis using the unweighted UniFrac distance metric (β-diversity) shows that samples cluster strongly by individual and not by dietary phase (Figure 2). Furthermore, we find that a Soylent diet significantly increases the medically-relevant Bacteroidetes to Firmicutes ratio (Figure 2).



Conclusion: Our results show that a short-term Soylent diet does not significantly affect microbiome diversity or the presence of specific species. Additionally, we report a significant transient increase in the Bacteroidetes to Firmicutes ratio in participants undergoing a Soylent diet, which has been associated with a lower risk of obesity and reduced intestinal inflammation. Future studies could employ transcriptomics and metabolomics to characterize changes in gene expression and metabolite profiles resulting from a Soylent diet. As additional research demonstrates the interplay of specific microbial consortia in influencing certain health outcomes, producers and consumers should consider the gut microbiome as an essential component of human health.



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