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Peter Smoak

Peter Smoak, Ph.D. candidate. Photo by Woody Myers

April 25, 2019

Calming Chemo’s Side Effects

UNC doctoral candidate Peter Smoak is taking a close look at how drinking kefir — a cultured drink similar to yogurt — may impact inflammation related to cancer treatments.

As chemotherapy wages war on cancer cells, collateral damage takes a toll on a patient’s wellness and quality of life. Peter Smoak is working on research to help lessen the damage that cancer treatment can cause.

Smoak, who came to UNC from Louisiana, didn’t start out thinking he’d be working with people who were fighting cancer. His Sport and Exercise Science undergraduate and master’s work focused more on athletic performance and nutrition. Then he met Laura Stewart, Ph.D., professor at UNC’s School of Sport and Exercise Science, and she sparked his interest in working with disease populations.

Stewart became his advisor, and after touring the UNC Cancer Rehabilitation Institute (UNCCRI), he decided UNC was where he wanted to do his doctoral work.

“I feel like I’m really contributing with disease populations, helping people live better lives. I feel like it puts my work to a better use,” he says. “Then my dad had prostate cancer a few years ago, and it kind of just hit home, like I need to be focusing on something more important.”

Smoak looks at the impact dietary interventions might have on people who have undergone chemotherapy and radiation, which can impact the gastrointestinal (GI) tract by killing beneficial gut bacteria.

“It can cause the immune system to freak out and attack the intestinal lining, which causes something called mucositis — basically just really bad ulceration and inflammation of the lining, and that causes all kinds of GI issues,” he says.

“Other bacteria leave the gut and get into regular circulation,” he says. That can cause systemic inflammation that may lead to arthritis, cancer, heart attacks, strokes and even depression.

Through his research, Smoak has focused on what might help calm inflammation and repair the GI lining.

“Our gut bacteria produce these little metabolites called short chain fatty acids that will tell our immune system, and primarily our T cells, to calm down,” he says, adding that they also increase mucus production — which may help the GI lining heal.

And that’s where kefir enters the picture. A tart, fermented milk product similar in taste to yogurt, kefir is 99.9% lactose-free, and significantly different than yogurt when it comes to repopulating the gut with good bacteria.

Probiotics are those live bacteria and yeasts that are good for your GI tract. Smoak explains that there are basically two types: resident and transient.

“If you imagine your intestines like a tourist area, your resident probiotics work there, and they have houses there and they kind of keep up everything,” he says. “Your transient probiotics are the tourists. So residential probiotics will actually take up living in your gut. They’ll reproduce and they’ll stay there. Your transient probiotics only last about two weeks, so you have to keep replenishing them.”

Kefir, Smoak points out, is one of the best probiotic sources for residential bacteria. Conversely, yogurt and supplements will primarily provide transient bacteria that will pack up and leave town in about two weeks.

And the density of bacteria in yogurt and kefir is different as well.

“Probiotic yogurts are going to have somewhere around 10 million colony forming units (CFUs), which means that in every gram of yogurt, there are about 10 million probiotics. Probiotic pills are somewhere around 100 million to about a billion CFU per gram. Kefir can be up to a trillion CFUs per gram.”

By repopulating the bacteria decimated by cancer treatments, the GI tract can heal, form a healthy barrier and keep bacteria where it belongs, rather than out marshalling the immune system to create inflammation.

Smoak, with a Provost Grant through the University Faculty Research Program and assistance from the Graduate Student Association, is seeking answers in an area that has had little scrutiny. 

With a cross-disciplinary group of faculty advisors including Laura Stewart, Reid Hayward, David Hydock and Nick Pullen, Smoak is working in the UNCCRI with 12 people going through chemo and radiation who are consuming kefir for 12 weeks, and 12 who are going through chemo and radiation and not consuming kefir. All 24 will go through a structured exercise regimen so that Smoak can see if kefir boosts the benefits they know exercise has on rehabilitation for cancer patients. He’ll be taking blood and stool samples (with the help of a firm called UBiome) and looking at markers for inflammation. He’ll also do quality of life surveys and a gastric distress survey to see how each patient is handling the increased probiotics.

By June (12 weeks after beginning), Smoak hopes to have data in-hand, with the goal of finishing his dissertation before fall. After that? “I’d like to just continue this kind of line of research, and I love teaching,” he says.

–Debbie Moors