Everybody eats, everybody poops: What I did this summer (by Vayu Maini Rekdal)

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“how much poop do you have?”

“not too much, it’s pretty loose this time. Perhaps a few milliliters”

“I think it’s fine. Let’s just go with it. Put it in the milkshake machine. We need to transplant it later today.”

My supervisor glanced at me, his face serious. We continued our tour of the research facility.

I vividly remember laughing quietly to myself that day, after witnessing a seemingly normal conversation at the Department of Gastroenterology at the Mayo Clinic in Rochester, MN. Here I would spend the next ten weeks expanding my understanding of the food we eat, and how it impacts us. I would research the dauntingly complex world within us – a dynamic world where 100 trillion inhabitants live under the vaguely defined laws of an ever-changing, dynamic environment. I’m talking about our gut.  

In a previous blog post, I gave a brief overview of my summer research, outlining the basic background facts and purpose of my project. Here’s an updated version – one devoted to recollection and reflection.

The human gastrointestinal (GI) tract is fascinating. It harbors over 100 trillion microbial cells, outnumbering the number of human cells by 10-fold, and the human genome by 150-fold. To this point, it’s easy to forget that humans carry two sets of genes:  those encoded in our own genome and those encoded in our microbiota; we genetically inherit only 1% of our genes from our parents, and the rest – the microbial genes, or ‘microbiome’ – we acquire from the environment.

Inherited genetic material is embedded in our DNA, the basic building blocks of life, and is subject to relatively little change during our lifespan. The microbiome, however, is a dynamic ecosystem shaped by selection and competition – one that changes depending on how we live. Of a number of factors, diet exerts the largest influence on our gut microbiome, profoundly affecting both form and function; changes in a normal gut microbial functioning and community composition is associated with a number of disease states, including colon cancer, obesity, diabetes, Irritable Bowel Syndrome, and Inflammatory Bowel Disease.  As such, dietary modulation of the gut microbiota has become a hot topic of research, because diet potentially represents a simple and straight-forward treatment for a number of common ailments.

In industrialized countries where food habits are deteriorating on the daily, gastrointestinal diseases seem to be on the rise, despite much scientific progress in food and health. Changes in normal GI functioning causes significant societal costs, but also social and personal costs for individuals. For many people, these costs come as changes in normal gastrointestinal motility, in the form of constipation, diarrhea, or abnormal bowel movements – symptoms that seem relatively simple to treat but nonetheless can heavily impair life quality. Yet, the rudimentary physiological mechanisms underlying changes in GI motility – be it gut microbes, diet, genetics, or a combination – remain largely unknown.

This summer, I spent ten weeks exploring the role of diet-gut microbial interactions in GI motility. More specifically, I used mice to investigate the effects of three dietary components on gut microbial community composition and whole gut transit time. The dietary components – ferrous sulfate (FeSO4), isomalt, and raffinose – are widely consumed and are known to cause GI symptoms. With this in common, they served as useful models for answering my research question. Isomalt, an indigestible carbohydrate and low-calorie sugar substitute, can cause diarrhea. Raffinose is a dietary fiber found in a number of vegetables (beans, cabbage, brussel sprouts – you probably know here I’m going with this) and can cause bloating. FeSO4, known to cause diarrhea/constipation, is the most common treatment for iron deficiency anemia, the world’s most widespread nutritional deficiency. My goal was to figure out what these dietary components do to you and your gut.

Combining molecular and physiological techniques with bioinformatics analysis, I was able to identify significant microbial and physiological changes that occurred due to dietary changes. For example, I showed that changes in GI transit can be concordant with shifts in the gut microbial community composition, highlighting the possible role of diet-microbial interactions in regulating GI transit. Due to the nature of the research environment, I do not want to disclose too many details. However, the results were promising, and further studies are underway to test the emergent hypothesis. I will return to the Mayo Clinic this winter to continue the research project.

As the summer is quickly reaching is end, I can’t help but to look back at that conversation I witnessed during my first day at the job. Today, I recall the conversation with fascination rather than awkwardness, probably because I am aware of what the people actually discussed. They talked about the preparation of a fecal matter transplant, or FMT. As unglamorous as it sounds, the FMT has emerged as an extremely efficient treatment for a number of GI diseases, especially extreme diarrhea; the transfer of feces from a healthy individual to a sick individual can quickly restore normal functioning in more than 95% of people. In combination with many other experiences, this conversation and the insights it entailed have improved my understanding of our gut and overall health. This understanding is also one of the more important lessons from my summer.

More broadly, my experience at Mayo has changed my view of food, complicating my view of what we eat and how we prepare it. It has solidified my belief that the complexity of science has the power to transform our rudimentary, everyday experience of food. Before this summer, I naively thought that the transformative power of science extended only to the mental realm, that science could only be used to manipulate texture and flavor in the pursuit of deliciousness. However, after a summer at a world-leading medical institution, I realize that science also has the power to transform our physiological experience of food, by changing and modifying our inner workings. As an aspiring scientist-chef, I see science as the key that will facilitate the alignment of the physical and mental experience for one single purpose: to develop, prepare and share foods that are as delicious to as they are nutritious.

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