Researchers have identified an unexpected link between diet and the effectiveness of cancer treatments. In a study published in Nature, scientists found that certain diets typically classified as unhealthy or high in fat actually improved the response to immune checkpoint inhibitors in mice.
These drugs are a common form of cancer immunotherapy that help the immune system recognize and attack tumor cells. The findings suggest that the success of these treatments depends not only on the presence of specific gut bacteria but also on the foods that allow those bacteria to thrive.
The Obesity Paradox in Cancer Treatment
The investigation grew out of a longstanding puzzle in oncology known as the obesity paradox. While excess body weight is generally linked to a higher risk of developing cancer and poorer outcomes, several clinical studies have observed that patients with a higher body mass index sometimes respond more favorably to immune checkpoint inhibitors.
To understand this contradiction, the research team tested 12 different diets in mice. They discovered that some diets associated with obesity improved the animals’ responses to immunotherapy, even when the animals consumed these diets for relatively short periods. This suggests that the treatment advantage associated with higher body weight may not be caused by the weight itself, but rather by the combined influence of diet and gut bacteria on the immune system.
Gut Bacteria and Food Synergy
Daniela Quail, an associate professor at the Rosalind & Morris Goodman Cancer Institute, co-led the research. She emphasized that the relationship between nutrition and cancer treatment is more complex than standard health advice suggests.
“There is a synergistic relationship between the bacteria that reside in our GI tract, and the food we eat,” Quail said. “Even with the right composition of bacteria in your gut, the foods you eat to nourish those populations can determine whether or not you respond to treatment.”
The study, titled “Diet-microbiome synergy underlies obesity-associated immunotherapy efficacy,” was co-authored by McGill PhD graduate Lysanne Desharnais and other senior researchers including Logan Walsh from McGill and collaborators Bertrand Routy and Arielle Elkrief from CR-CHUM.
The results challenge the assumption that only “healthy” diets support cancer treatment. However, the researchers stress that these findings should not encourage patients to adopt diets that promote obesity. Excess weight carries established health risks, and the study does not demonstrate that adopting such diets would improve cancer treatment in humans.
Instead, the scientists aim to identify the specific mechanisms by which certain foods influence the gut microbiome. By understanding how these interactions affect cancer treatment, researchers hope to develop safer methods to enhance immunotherapy efficacy without exposing patients to the health risks associated with obesity.
Funding for the study was provided by the Canadian Institutes of Health Research, the Canadian Cancer Society, the Terry Fox Research Institute, the Canada Foundation for Innovation, and philanthropic supporters including La Vie en Rose and the Bachynski Family Foundation.
Source: ScienceDaily
