URBANA, Ill. — Many modern cancer treatments are highly effective at reducing or eliminating tumors, but they can also cause severe gastrointestinal symptoms that impact patients' quality of life or lead to discontinuation of treatment. A new analysis from University of Illinois Urbana-Champaign researchers reveals the nutrition therapies that are most effective at minimizing GI distress.
"Understandably, there's a major focus on eliminating the tumor, but alleviating symptoms that impact the continuation of treatment and helping the patient to maintain quality of life should be an equal priority," said lead study author Brett Loman , an assistant professor in the Department of Animal Sciences and the Division of Nutritional Sciences (DNS); both units are part of the College of Agricultural, Consumer and Environmental Sciences at Illinois.
Nutrition therapy is a common addition to medical treatments for cancer. Dieticians may prescribe oral nutrition supplements or may meet with patients one-on-one in nutritional counseling sessions. But Loman says these are mostly aimed at helping patients undergoing chemotherapy or radiation avoid excessive weight loss or improve immune function, not specifically to ease GI symptoms.
However, studies that track the efficacy of nutrition therapy for weight loss and other targets often keep track of GI symptoms on the side. Loman knew there could be a wealth of information buried in these reports, so he and co-author Zainab Alzoubi , a former master's student in DNS, combed through nearly 16,000 published studies to find the most effective therapies.
"Our short-term goal is to provide high-quality evidence to practitioners to utilize in their practice," Loman said. "Long term, we'd like to create a treatment regimen for people to reduce their GI symptoms based on the type of cancer and the therapy they're receiving. This meta-analysis is the first step."
After identifying thousands of studies on nutritional therapies for cancer patients, Loman and Alzoubi narrowed their search to 139 that included high-quality data on the incidence and severity of multiple GI symptoms like nausea, diarrhea, and vomiting. The final pool of studies involved nutrient supplements (such as specific amino acids), dietary counseling, or oral nutritional supplementation (usually meal replacer drinks), and represented more than 10,000 patients altogether. The research team then used the data in those studies to conduct over 150 new analyses.
Although nutrient supplementation was the most variable category of studies — including dozens of probiotics, amino acids, fibers, fats, and more — it was also the largest, with 9,572 patients represented in 126 studies. Further, this intervention type seemed most effective at reducing nausea, vomiting, and diarrhea.
The team looked at the interactions between cancer type, 12 GI symptoms, and each nutrient studied, finding, for example, that probiotics reduced diarrhea incidence during colorectal cancer. Among the nutrients, general standouts included amino acids (especially glutamine); probiotics, prebiotics, and synbiotics; herbs and minerals (especially ginger and zinc); and essential fatty acids (such as omega-3s).
"If we take this information and provide it to dietitians, they could match nutrients to each GI symptom, cancer, or treatment type, and hopefully their interventions could be more effective for improving GI distress," Loman said.
The next category was dietary counseling, where dieticians meet one-on-one with patients to prevent weight loss and inflammation during treatments. Loman says the conversations frequently cover what patients are eating, and offering suggestions about what foods to include on the menu. Studies in this category showed counseling can effectively reduce diarrhea, constipation, nausea, anorexia, and vomiting. However, due to the highly personalized nature of dietary counseling, the researchers couldn't dig deeper to learn specifically what worked.
"Having access to someone who can help personalize or guide your nutrition can reduce some of the most common GI side effects," Loman said. "We think that group could take a cue from what we learned in the nutrient supplement analyses and start integrating some of the more effective nutrients into their recommendations. They're really the boots on the ground, figuring out how these nutrients could work for each individual."
The final category of studies focused on oral nutritional supplements, which tended to be nutritionally complete meal replacer drinks. While they delivered the necessary nutrients, the researchers found they didn't help with GI symptoms.
"Unfortunately, we didn't see any benefit from oral nutritional supplements," Loman said. "We also didn't see any negative effects, which means they weren't causing GI symptoms, but they weren't reducing them."
Loman says that if new products could be formulated with beneficial nutrients like ginger or probiotics, they could reduce GI symptoms and deliver complete nutrition. He is planning to test promising formulations in pre-clinical and clinical trials in the future.
The study, "Nutrition Interventions in the Treatment of Gastrointestinal Symptoms during Cancer Therapy: A Systematic Review and Meta-analysis," is published in Advances in Nutrition [DOI: 10.1016/j.advnut.2025.100485 ].
Research in the College of ACES is made possible in part by Hatch funding from USDA's National Institute of Food and Agriculture. This study was also supported by a Jonathan Baldwin Turner Graduate Fellowship through the Division of Nutritional Sciences at Illinois.
Loman is also affiliated with the Personalized Nutrition Initiative and the Microbial Systems Initiative at U. of I.
