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Dietary Fiber and IBD: Eating the Right Stuff

Dr. Eric Martens researches how diet influences our gut

As an inexperienced freshman in biology, Eric Martens was bold enough to go knocking on lab doors to get his first-ever research experience. He was fortunate enough that a researcher at Washington University in St. Louis opened one of those doors and welcomed him in. 

A decade later, Dr. Martens had a PhD in microbiology from the University of Wisconsin-Madison. He returned to St. Louis to complete his postdoctoral research in microbial genomics with Jeffrey Gordon at Washington University Medical School. And now he’s making fiber-rich smoothies to feed our distal gut bacteria.

We’re trying to identify effective dietary therapies using nutritional supplements that look and taste good. They need to appeal to both the human patient and their gut bacteria.”

Fiber is…Complicated

Inflammatory Bowel Disease (IBD) research has long grappled with a conundrum. While genetics can indicate someone’s susceptibility to IBD, genetic predisposition alone is a poor predictor of the disease. So, there must be other contributing factors such as diet or the normally beneficial community of bacteria that live in the human intestine.  

As Associate Professor of Microbiology and Immunology at the University of Michigan Medical School, Dr. Martens considers both. His focus is on the role of fiber. But not any fiber—he’s interested in the right fiber in the right amounts. His goal is to keep gut bacteria well-fed and out of trouble. Because what we eat—or don’t eat—can have some surprisingly troublesome side-effects. 

Protecting the Protective Layer

IBD is growing worldwide but is more prevalent in the industrialized world, where our consumption of dietary fiber has declined. Dr. Martens has found that these complex carbohydrates—abundant in vegetables and grains—play a pivotal role in our digestive health. While we humans are unable to digest dietary fiber directly, our gut bacteria rely on it for nourishment. And when that isn’t available, bacteria turn to the next best thing—the protective, high-carbohydrate mucus lining our intestines. 

This mucus layer normally forms a barrier that keeps bacteria at a “safe distance” from our intestinal epithelium and our immune system. Dr. Martens posits that chronic or transient reductions in fiber trigger gut bacteria to erode the mucus layer. Most of us can tolerate those intrusions under ordinary circumstances. For those with IBD and a genetic predisposition to hyperactive inflammation, however, it can trigger or exacerbate disease flares.  

Dr. Martens’ aim is to restore a healthy balance in the gut and keep bacteria away from our epithelial tissue. His research focuses on determining proper dosages and forms of fiber for IBD patients to supplement or reintroduce to their diet.  

Hence the smoothies.

Between the Grocery Store and Big Pharma

As Dr. Martens sees it, his work lives in the space between the local grocery store and big pharma. His lab employs a powerful combination of genomic, molecular genetic, and biochemical techniques in its investigations. He counts on a local and international network of collaborating researchers and corporate partners. Among them are pharmaceutical giants like Elli Lilly and Takeda, with an interest in drug therapies to block mucus degradation. A more local partner is the Kellogg Company—“one of the oldest fiber companies in the world,” according to one Kellogg scientist.  

“My work lives in the space between the local grocery store and big pharma.”

But home blenders also have a role to play. Dr. Martens and his colleagues have beta-tested countless smoothie formulations to find the right mix of dietary fiber. A primary challenge, however, is how to step beyond the specificity and highly controlled conditions of pre-clinical mouse model research. Testing these formulations with human patients involves countless, uncontrollable variables—genetics, dietary habits, and the teeming microbiota of the gut. It’s work that requires persistence and at least some degree of confidence in the eventual outcome. 

Much like knocking on doors until the right one opens. 

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