For most people, yeast is just the stuff that makes bread rise. But scientists at two major universities in Dublin, Ireland, have found that a supplement made from yeast could help the body fight cancer. The researchers, from Trinity College Dublin and University College Dublin, discovered that feeding obese laboratory mice a yeast-based supplement helped their bodies create stronger immune cells that can attack tumors.
The key ingredient is called yeast beta-glucan. It's already sold as a food supplement and has a strong safety record. In the study, mice were fed this supplement for 4 to 12 weeks while eating either a standard diet or a high-fat diet. Then the researchers challenged their immune systems with colorectal, skin, and breast cancer cells.
What they found was striking. The supplement didn't just give the immune system a temporary boost. It actually reprogrammed stem cells in the bone marrow — the cells that make all other blood and immune cells — to produce cancer-fighting immune cells that worked better and lasted longer. This is the first time researchers showed that simply eating yeast beta-glucan, rather than receiving an injection, can trigger this reprogramming.
The finding matters especially for people who are overweight. Obesity weakens the immune system, making it harder for the body to fight infections and cancer. Even worse, the researchers discovered that immune problems caused by obesity don't go away even after someone loses weight. But the yeast supplement reversed those long-term immune defects in the mice.
The study was led by Associate Professor Frederick J. Sheedy from Trinity College Dublin and Professor Helen Roche from University College Dublin. Dr. Anna Ledwith, a postdoctoral researcher and first author on the paper, said they wanted to know whether the supplement could reprogram early-stage immune cells to produce lasting anti-tumor responses. The answer, apparently, is yes.
Roche called it a major step forward. "This research paves the way for dietary intervention studies in people living with obesity, chronic infections and other immunocompromised populations," she said. The yeast supplement they used — WellmuneTM from Kerry Group — is already commercially available, which means clinical trials in humans could move quickly. Sheedy said the goal isn't to replace chemotherapy or immunotherapy but to complement them, potentially improving vaccine responses and resistance to infections along the way.
The findings were published in the journal Cell Reports.