Scientists discover that some “unhealthy” diets can boost cancer immunotherapy in mice
In a surprising discovery, scientists found that certain diets associated with obesity can make cancer immunotherapy more effective in mice, challenging traditional assumptions about diet and cancer treatment. The findings suggest that the secret may lie in how food interacts with gut bacteria to strengthen the immune system's response to cancer.
Key points
- Some diets linked to weight gain improved immunotherapy responses in mice, researchers at McGill found.
- The team tested 12 diets and says diet and gut bacteria work together to affect treatment.
- Researchers warn patients should not adopt obesity-promoting diets based on these mouse results.
Scientists have found that some diets usually seen as unhealthy or fattening improved responses to a common cancer immunotherapy in mice, according to research published in Nature. The work was co-led by Daniela Quail, an associate professor at McGill's Rosalind & Morris Goodman Cancer Institute, with McGill scientist Logan Walsh and CR-CHUM collaborators Bertrand Routy and Arielle Elkrief.
The study examined how diet affects immune checkpoint inhibitors, drugs that help the immune system recognize and attack cancer cells. The researchers say the results suggest treatment success may depend on both the gut bacteria present and the foods that feed them.
Diet and gut bacteria
Quail described a link between gut bacteria and food, saying the right bacteria may not be enough on their own. The team tested 12 diets in mice, and some diets associated with obesity improved responses to immunotherapy even when eaten for relatively short periods.
The work grew from the "obesity paradox": obesity is generally tied to higher cancer risk and death, yet some studies found patients with higher BMI sometimes respond better to these drugs. The findings suggest excess weight may not be the main cause of that advantage.
There is a synergistic relationship between the bacteria that reside in our GI tract, and the food we eat
— Daniela Quail
Caution for patients
The researchers stress the results should not lead cancer patients to eat diets that promote obesity, noting excess weight carries established health risks and the findings do not show such diets would help humans. They hope to identify how foods affect the microbiome so safer ways can be developed to make immunotherapy more effective.
The study, "Diet-microbiome synergy underlies obesity-associated immunotherapy efficacy," was published by McGill PhD graduate Lysanne Desharnais, Quail and collaborators. Funding came from the Canadian Institutes of Health Research, the Canadian Cancer Society, the Terry Fox Research Institute, the Canada Foundation for Innovation and philanthropic supporters.
