Leigh Greathouse

Season 3 - Episode 345

November 13, 2020

Leigh Greathouse
Leigh Greathouse

As a 24-year old, Leigh Greathouse developed a rare form of cancer, an experience that would shape her path into the study of diet and disease. Dr. Greathouse, assistant professor in human sciences & design at Baylor, is a leading researcher into the relationship between diet, the microbiome, disease and health. On this Baylor Connections, she shares her personal story, breaks down key research projects in her field and provides a framework for listeners to think about the relationship between diet and health in their own life.

Transcript

Derek Smith:

Hello, and welcome to Baylor Connections, a conversation series with the people shaping our future. Each week, we go in depth with Baylor leaders, professors, and more discussing important topics in higher education, research and student life. I'm Derek Smith and our guest today is Leigh Greathouse. Dr. Greathouse is a leading researcher into the relationship between diet, the microbiome, disease, and health. She serves as assistant professor in Human Sciences and Design at Baylor. Dr. Greathouse was motivated to pursue cancer research after surviving her own battle with cancer shortly after college, noticing the impact of diet on our health during and after treatment, she began to work in early microbiome and disease research and has advanced the field through research and scholarship. Earlier this year, she was awarded a career development award from the Department of Defense to study dietary impacts that could improve treatment outcomes for patients with colon cancer. It's been an exciting year, even amidst the craziness and a busy year. And she's with us today here on the program. Dr. Leigh Greathouse. Thanks so much for joining us.

Leigh Greathouse:

Thanks for having me.

Derek Smith:

Well, when many people hear the words, diet, and health maybe it's easy to think about weight, weight loss, long-term health goals. So to set the stage for what we're going to talk about here over the next 20 minutes or so, when we discuss diet, health and the microbiome with you, how should we think about that relationship?

Leigh Greathouse:

Yeah. Sure. That's a great question. So I think the best way to think about it is imagining that you have a group of microscopic friends that live in your gut and they're completely dependent on you to stay alive, but most of them also protect you against pathogens or bad microbes that can make you sick. However, if you don't feed them enough of a variety of vegetables, fruits, whole grain, they actually start to function less effectively. And so long-term, this can even start to make you sick or contribute to disease. So what's even more interesting now that we're looking into the research is that they not only affect your immune system, but they also affect your mental health. So to give you a quick example, there's a couple of studies now showing that, doing what we call a fecal microbiome transplant, it's essentially just transplanting a more healthy like gut microbe system, doing that in children with autism actually can reduce their autistic behavior issues by about 35%. So there is so much information that we're still learning about the microbiome and how it affects all aspects of health, both physically and mentally.

Derek Smith:

And so we think about it certainly from a long-term standpoint, the healthy gut, it can improve our health. Are there more acute aspects as well, ways that that healthy microbiome that we should think about it helping us in the shorter term as well?

Leigh Greathouse:

So in the short term, I can say that if you drastically change your diet, they've shown in studies that within 24 hours, your microbiome can change fairly drastically. Another example of this is antibiotics. If you take antibiotics, your gut microbiome can change drastically. And sometimes it recovers to about normal and other times it never recovers back to normal. So it just really depends on again how diverse your microbiome is to start out with. So I would say that would be some of the short-term effects.

Derek Smith:

When we talk about your discipline, studying the microbiome and health. I know as fields go, it's relatively young and it's growing in some exciting ways. How has the field grown in recent years?

Leigh Greathouse:

Wow, that's a really loaded question. So many ways it has grown, it's absolutely exploded since about, I would say 2006 when some of the first publications started to come out that really were paradigm shifting to now. So the first studies were really looking at the association with obesity and irritable bowel syndrome. And now we've shifted into looking at heart disease, diabetes, and cancer, which is what my focus is. So having this knowledge is such a benefit for not only the patient, but also the clinician. So that's just one example, but I will caveat this by saying that some of the not so great effects of the super explosion of data has been in marketing of probiotics. So some of them could have the potential to work and have shown benefit in some situations, but for the majority of people that are fairly healthy, normal with minimum or no disease, probiotics are just not going to help you.

Derek Smith:

Maybe a broad question, but are there ways you would encourage people to whether it's vetting sources or just some tips for if they see or hear something as it relates to this to kind of be armed with information that helps them process whether it's useful or not?

Leigh Greathouse:

Yeah, sure. So I always recommend a couple of different sources. So if you just want really good source on healthy eating, I would go to eatright.org. That is the best place to get all of the best information on how to feed you and your family, a healthy diet. If you want the best information from a really good third-party source, I would go to consumerlabs.com. They are third-party vetting system for all supplements. They do third-party testing that doesn't have any funding from any of the people that supply the supplements for testing. So it's a really great unbiased way to find if what supplement you're taking actually really is doing what it's supposed to do.

Derek Smith:

We are visiting with Dr. Leigh Greathouse on Baylor Connections. And Dr. Greathouse, this discipline and your really mission, I know it is personal for you. And we mentioned at the top of the program briefly that you had your own battle with cancer. Can you take us a little bit inside those experiences and share how that shaped the direction you've gone since then?

Leigh Greathouse:

Sure. So when I was doing my master's in Exercise and Sports Nutrition at Texas Woman's University, it was about when I was 24 at the time. So that was 1998. So I just really aged myself there. But anyway, I was doing my masters and about halfway through, I started feeling really sick. It came on very suddenly within a week or so, and through a series of different episodes, they finally diagnosed fairly quickly within a few days that I had a massive tumor and it was on top of my uterus actually. And so what they did was they did a tumorectomy and then they diagnosed it as a stage four uterine leiomyomas Tacoma, which is really rare form of uterine cancer. So with that, I had a couple of more surgeries and did about six rounds of doxorubicin and amazingly, probably through the blessing of God and many prayers, I was clear or had a clean CT scan at the end of the year and in 99. So that experience really gave me a new sense of actually confidence to take more risks with what I really wanted to pursue, which was higher education and actually a PhD in Cancer Biology. So I kind of married up my two interests, which were eating healthy and cancer prevention. Because I knew that a lot of cancers are directly related to lifestyle, including dietary behaviors. So that was a real passion of mine, especially during my treatment, which I discovered when I was sick and doing chemotherapy, that one of the best ways to make myself feel so much better and have so much more energy is just really eating as healthy of a diet as I possibly could. And it gave me so much more energy. And that again, also really drove me to want to explore in more detail why that changed my overall wellbeing so much, so dramatically.

Derek Smith:

As you began to think about those relationships and kind of emerged from your own battle and began that pursuit in higher education, what shaped the areas that maybe you focused most closely, if you start out with disease, diet, cancer broadly, how have you honed in over the years to some of your more specific areas?

Leigh Greathouse:

Sure. So I would say broadly, my first interest was probably on this connection between obesity and cancer, because depending on which cancer you look at anywhere between a 10% to almost 40% increase in risk for certain types of cancers with just having obesity. And so that was one of my first major interests in exploring is this link between obesity and cancer risk. And then around 2010, I believe a paper came out showing that the microbiome could really explain a lot of the link between obesity and diet. And essentially what they did was they took twins, one who had obesity and one that was lean and they took stool samples from these twins and they implanted them in mice that didn't have any microbes. And they fed them the exact same diet and the mouse that got the stool sample from the twin with obesity became obese. And the one from the lean stool sample remained lean, even eating exact same calories and the exact same diet. So that's what really had a paradigm shift in my thinking of, wow, maybe this, the link that I've been looking for and how obesity shapes cancer risks since we know diet and obesity is such a strong risk factor for so many different types of cancer. So I thought this would be a really exciting way to explore that link. And that's really kind of what got me started.

Derek Smith:

This is Baylor Connections. We are visiting with Dr. Leigh Greathouse, Assistant Professor in Human Sciences and Design at Baylor. And Dr. Greathouse, as you talked about colon cancer specifically there, I know that's been very much in your focus here because this year you received the exciting news that you'd received a career development award from the Department of Defense to study links between diet, and treatment. And I'll just mention, I think people beyond just the work you do owe you a debt of gratitude because you delve into some things that I think most of us might be a little squeamish about. And as we mentioned, we're going to be talking about, you mentioned working with stool samples and in this case, your grant is going to help people who deal with a very unpleasant side effect of chemotherapy in some cases, called chemotherapy-induced diarrhea. And so I think people can appreciate how much better your work could make people's lives, if you can reduce that. But can you take us a little bit inside what it is that this career development award is going to allow you to do?

Leigh Greathouse:

Yeah, absolutely. So the main focus of this award, like you said, was really trying to identify factors in the gut microbiome or in our diet that may be predictive of people who are going to succumb to chemotherapy-induced diarrhea or the severity of it. It's a really horrible side effect. That's not just short-term, it can have longterm affects as well, even after you are done with treatment. And so about 50% of people that are on treatment for colon cancer will develop chemotherapy-induced diarrhea. So it's a large group of people that have this side effects. And then if you do, depending on the severity of it, there's not a whole lot of treatment other than a couple of different types of drugs, or just reducing the dose of chemo that you're on. So it becomes less effective and maybe you're on chemotherapy for longer periods of time. So this award, what it's going to allow us to do is enroll about 112 individuals with stage two or three colon cancer and follow them throughout their treatment. And so what they're going to be providing to us is information on their diet. They're going to be providing us stool samples on a regular basis, as well as any of the blood samples that we get from the regular clinical visits. And so what we're going to be able to use those to do is look at the microbes in their gut before they even start therapy and ask the question, can we use the factors or the microbes in their gut to predict or build a predictive algorithm to actually show who's going to develop chemotherapy-induced diarrhea. And know if we can predict that maybe we can use these dietary factors to help prevent them even getting chemotherapy-induced diarrhea, or looking at the changes in the gut microbiome over time, identify who actually doesn't get chemotherapy-induced diarrhea, and maybe it has something to do with the collection or function of the microbes in their gut or their diet before they started treatment. So there's a lot of opportunities to look for ways to either prevent or control chemotherapy-induced diarrhea so it doesn't last as long or so they don't even have to encounter this problem longterm.

Derek Smith:

You just described this a little bit, but I want to ask you specifically, I think we hear more and more about looking for biomarkers, for various things, but more specifically in terms of what you just described, what does that mission look like to find an identify those biomarkers?

Leigh Greathouse:

Sure. So I can give you an example. I'm sure a lot of people have heard about this new kit that you can do at home, that you just have stool samples and you send it back in, it's called Cologuard. So that is based on biomarker analysis. And so what they did was they did multiple studies with hundreds of individuals that went on to develop colon cancer and followed them over time to identify what genetic or microbial biomarkers were the most predictive of developing or having colon cancer. So this is one way that you can develop biomarkers by following groups of people that you take samples from over time and identifying what factors in their genetics or in their diet or in their gut microbes are going to predict with high sensitivity specificity, those that are going to either develop or have colon cancer or a specific type of cancer. So usually this requires multiple years and hundreds of individuals to develop a good clinically useful biomarker.

Derek Smith:

Visiting Dr. Leigh Greathouse. And Dr. Greathouse, what local partnerships play a role in you conducting this work over the next few years?

Leigh Greathouse:

So I worked really hard to develop some relationships with physicians at Baylor Scott & White Health. And it's really been through those relationships with Dr. Lucas Wong and other physicians that we were actually able to even start doing this study. So those relationships have been instrumental. I've also been really fortunate to be able to have a collaboration with several folks at the Baylor College of Medicine, including Joe Petrosino, who's the director of the Alkek Microbiome Sequencing Center. And so I work with him on several projects and they do a lot of sequencing for us to be able to identify what microbes are in the gut bacteria and the samples that we have from our patients.

Derek Smith:

Well, that's great. We'll Look forward in the years ahead, as this project develops to seeing what news comes out of it, what findings are uncovered. And as we head into the final few minutes, I want to shift gears slightly and ask you, I know that mentoring students in your lab and in your classes is a big part of what you do. And with this being such a young field and an opportunity for the scholars that you train to have a big impact on, what does it mean for you to be able to train students in this area? And what do you see in the students who really have a passion for this?

Leigh Greathouse:

Yeah, so I think that's one of my major passions even more so than the research even is mentorship of students and young investigators or scientists that wants to get into this field. I love mentoring students. And I feel like, I think I've really been given a gift to do so and helping identify what their career path could be and then helping them think outside the box and really hone in on what their passion is and identifying what skill sets they have or what skill sets they need to obtain to reach their ultimate goal. So I think some of the students that have been most successful are those that are passionate about really investigating and not discouraged by the constant failure that always plagues all experiments in science, that you don't let that get you down. And that you still have enough passion and enough drive and really it's persistence that pays off. I can't tell you how many times I've seen exceptionally gifted students at least in graduate programs, they don't make it because they don't have that persistence, that drive. So it's not really about how smart you are, it's about how persistent and how passionate you are in finding those answers to those questions, because science is extremely challenging mentally.

Derek Smith:

Well, it's exciting to see that growth and I'll mention too, before we go, you talked about growth in your discipline, we're even seeing that in your department. I mentioned that you are a assistant professor in Human Sciences and Design, and if maybe there's some alums or people around Baylor who thought, "I haven't heard that phrase before." What does that mean? What does that phrase mean to the growth of your department?

Leigh Greathouse:

So the change in the name of our department is really exciting. I think it really speaks to the fact that we're embracing a new aspect of our field, specifically focusing on research and the hiring of a lot of new faculty within our department. In fact, in nutrition, we just hired three new faculty, two of them being research focused. So I think you will only see extreme amounts of growth and research in our department over the coming years and probably a lot more funding as well.

Derek Smith:

Wow. Well, that's great. Well, very exciting and really great to visit with you, really appreciate your time. Thanks so much for coming on today.

Leigh Greathouse:

Thanks for having me.

Derek Smith:

Thank you. Dr. Leigh Greathouse assistant professor in Human Sciences and Design our guest today on Baylor Connections. I'm Derek Smith. A reminder, you can hear this and other programs online, baylor.edu/connections. Thanks for joining us here on Baylor Connections.