Long awaited updates (results and more)!

Dear Backers!

It's been a while since our last post, and we have a ton of updates for you.

Graduation!

We graduated in May! All of us are currently working in either research or clinical positions and are preparing for graduate and medical programs in the near future.

Our results!

We've worked very hard in the last few months analyzing and interpreting our data with students and faculty at UC Berkeley. In particular, we received help from Harneet Rishi, Lauren Lui, Michael Shapira, and Shyam Bhakta. After many revisions, we've submitted a manuscript for peer review to PLOS ONE, an open-access journal. In the meantime, a copy of the paper can be found here, on biorxiv.

Here's a copy of our abstract (a summarized form of the paper):

An interventional Soylent diet increases the Bacteroidetes to Firmicutesratio in human gut microbiome communities: a randomized controlled trial Ryan H. Hsu, Dylan M. McCormick, Mitchell Lee J. Seitz Jr., Lauren M. Lui, Harneet S. Rishi, Adam P. Arkin Our knowledge of the relationship between the gut microbiome and health has rapidly expanded in recent years. Diet has been shown to have causative effects on microbiome composition, which can have subsequent implications on health. Soylent 2.0 is a liquid meal replacement drink that satisfies nearly 20% of all recommended daily intakes per serving. This study aims to characterize the changes in gut microbiota composition resulting from a short-term Soylent diet. Fourteen participants were separated into two groups: 5 in the regular diet group and 9 in the Soylent diet group. The regular diet group maintained a diet closely resembling self-reported regular diets. The Soylent diet group underwent three dietary phases: A) a regular diet for 2 days, B) a Soylent-only diet (five servings of Soylent daily and water as needed) for 4 days, and C) a regular diet for 4 days. Daily logs self-reporting diet, Bristol stool ratings, and any abdominal discomfort were electronically submitted. Eight fecal samples per participant were collected using fecal sampling kits, which were subsequently sent to uBiome, Inc. for sample processing and V4 16S rDNA sequencing. Reads were clustered into operational taxonomic units (OTUs) and taxonomically identified against the GreenGenes 16S database. We find that an individual′s alpha-diversity is not significantly altered during a Soylent-only diet. In addition, principal coordinate analysis using the unweighted UniFrac distance metric shows samples cluster strongly by individual and not by dietary phase. Among Soylent dieters, we find a significant increase in the ratio of Bacteroidetes to Firmicutes abundance, which is associated with several positive health outcomes, including reduced risks of obesity and intestinal inflammation.

In summary, here are the three main findings:

1. No significant change in alpha-diversity was observed in the Soylent diet group. This is relevant because high diversity has been shown to be important for maintaining a healthy microbiome.

    

   

   Figure 1. Alpha-diversity quantified using the Shannon-Wiener and Gini-Simpson metrics. No significant changes are found during the Soylent diet phase.

2. Soylent-treated microbiomes do not cluster together. Originally, we hypothesized that the microbiomes of Soylent drinkers would start to resemble one another after several days of a Soylent diet. We find that this is not the case. Even after Soylent treatment, each person's microbiome most resembles their prior microbiome.

    

   

   Figure 2. Principle Coordinate Analysis of our microbiome samples. Samples are colored by participant. Samples that are similar appear closer to each other. The Soylent samples (X's) cluster with each participant's other samples rather than with each other.

3. A Soylent diet results in a significant increase in the Bacteroidetes to Firmicutes ratio. This ratio has been used as a medically relevant 'score' of microbiome health. A high ratio is associated with leaner individuals (in obesity studies) and a reduced risk of intestinal inflammation.

    

   

   Figure 3. Change in the relative abundance of four major phyla (i.e. large taxonomic groups) of bacteria. We found a significant increase in the Bacteroidetes to Firmicutes ratio (B) resulting from a Soylent diet.

We conclude that this diet, in the short-term, does not negatively affect microbiome composition in our current understanding of microbiome health.

World Congress of Gastroenterology Conference!

We presented our project at the World Congress of Gastroenterology Conference, hosted by the American College of Gastroenterology, in Orlando, Florida this past weekend! It was a great opportunity for us to communicate our findings to the clinical community and learn about how physicians currently approach the microbiome. Many projects presented there were centered around treating C. diff infections with fecal microbiota transplantations. We were definitely the youngest presenters in attendance.

 

Figure 4. Dylan, Mitchell, and Ryan at the World Congress of Gastroenterology Conference

 

Figure 5. We learned a lot about intestinal villi.

 

Figure 6. View of the exhibit hall at the World Congress of Gastroenterology

 

Figure 7. As it says, we greatly appreciate our 84 backers on experiment.com for making this study possible!

Thanks again to everybody who supported our crowdfunding campaign. You have given us an incredible opportunity to learn and mature as scientists.

Feel free to leave questions and comments below! We will get to them as soon as we can.