Nutrition Science researcher explores colorectal cancer disparities through diet, gut microbiome research

Written By: Rebecca Hoffa, rhoffa@purdue.edu

Colorectal cancer is the third most common cancer diagnosis in the United States, excluding skin cancers, according to the American Cancer Society, with more than 150,000 new cases of colon or rectal cancer being estimated for 2024. While the increased number of people receiving screenings has reduced overall colorectal cancer incidence, early onset colorectal cancer cases have continued to climb.

Patricia Wolf, assistant professor in Purdue University’s Department of Nutrition Science, is working to reduce this statistic, particularly for marginalized and underserved communities. With a recent $917,000 grant from the American Cancer Society, Wolf is exploring how the metabolism of cysteine, a protein in the diet, interacts with the gut microbiome, or the microorganisms that make up the human digestive tract, to influence colorectal cancer incidence.

Patricia Wolf(Photo provided)

“I’m interested in cysteine metabolism because when microbes break it down, they form a genotoxin — hydrogen sulfide — and my previous work has shown that these microbes are abundant in the gut and that they might be associated with cancer,” Wolf said. “Our previous work, which originally looked at differences in the gut microbiome between non-Hispanic whites and Black individuals, showed that some of these cysteine-metabolizing bacteria were associated with cancer in Black participants. I wanted to follow this up and start thinking about why these microbes might be more abundant and if that’s related to dietary intake.”

Based on her previous work, Wolf is hypothesizing that the foods that are available in communities also play a role in colorectal cancer risk. She explained individuals with limited access to whole foods who consequently consume more processed foods may be more likely to have increased amounts of cysteine.

“Cysteine isn’t only abundant in high-protein foods — it’s also a food additive,” Wolf said. “I’ve been thinking that it’s potentially an understudied area: How are food additives impacting the gut microbiome?”

Pius Sarfo Buobu, a graduate student in the College of Health and Human Sciences, connected with Wolf’s research because of his clinical nutrition background and passion for population nutrition and translational research. He shared that he’s excited to dive deeper into understanding the direct implications of diet in underserved communities and populations as part of Wolf’s research team.

“The food environment defines what you have available, what you have access to and the types of food you can make a choice from.” Buobu said. “What types of grocery stores and restaurants do you have in your vicinity? Is it dominated by fast-food joints? All of these factors likely can influence colorectal cancer development. For instance, if you have a lot of fast-food joints, you might be consuming a lot more processed foods and a high-fat diet, which have been linked with developing colorectal cancer. It’s not like the food is acting in isolation. It impacts the gut microbiome, and the microbes could then influence colorectal cancer development.”

Pius Sarfo Buobu(Photo provided)

Wolf was also recently awarded an AgSEED grant from the Purdue College of Agriculture, in which she hopes to further explore rural food environments and how they influence colorectal cancer risk, going beyond even some of the demographic disparities she’s explored in the past.

“There’s very limited data on the gut microbiome in general in underserved communities,” Wolf said. “The hope is that focusing on these communities will provide more data in general to the field that will push us to understand some of these mechanisms. I want to make sure that my work eventually serves these communities.”

Wolf and Buobu both noted that past research literature has shown healthy diets are important for taking protective measures against colorectal cancer occurrence, particularly diets that are rich in fiber sources, such as whole grains, fruits and vegetables.

 “A Mediterranean dietary pattern seems to have, based on what I’m interested in, the right ratios of amino acids to protect from some of these risk factors, assuming that changes what the microbes are doing,” Wolf said.

Wolf often looks toward the future as her work continues to evolve, with her goals being to bring about change in the policy and the food industry to help lower colorectal cancer rates.

“I keep seeing potential connections in how it might impact underserved communities, but also, I’m curious about early onset colorectal cancer, which is projected to be the leading cause of cancer in people under the age of 50 by 2030, and some of our preliminary data shows that these bacteria are associated with early onset colorectal cancer,” Wolf said. “I’m hoping that we can keep following it up and find ways that we can utilize food to make changes.”