Yeast beta-glucan may boost anti-tumor immunity in obesity, mouse study finds

An Irish study has found potential in food supplements made from yeast to help the body make stronger immune cells to fight cancer in four to 12 weeks. 

The researchers from Trinity College Dublin and University College Dublin (UCD) demonstrated “for the first time” that adding yeast supplements to the food of obese mice may change how their immune cells grow and create better cancer-fighting cells.

When overweight, the immune system weakens. This makes it more difficult for the body to fight tumors, the researchers explain. Supplementing with yeast could therefore become a “safe and natural way to help the immune system fight cancer.”

“We wanted to investigate whether a common dietary supplement, yeast beta-glucan, could reprogram early-stage immune cells in the bone marrow to produce long-lasting, enhanced anti-tumor immune responses,” says Dr. Anna Ledwith, postdoctoral researcher at the UCD and Trinity College Dublin, and first author of the research paper.

“Mice were fed a standard or high-fat diet supplemented with yeast beta-glucan for four to 12 weeks, and then their immune system was challenged by different types of cancer cells, colorectal, skin, and breast cancer. The study also tested whether yeast supplementation could overcome immune dysfunction caused by obesity and whether protective effects persist after weight loss.”

Obesity and immunity

The experimental study, published in Cell Reports, notes that obesity is linked to immune dysregulation, driving chronic inflammation and compromising the body’s defense against tumors.

“This research paves the way for dietary intervention studies in people living with obesity, chronic infections, and other immunocompromised populations. The yeast beta-glucan used, Wellmune from Kerry Group, is already food-grade and commercially available, facilitating rapid clinical trials,” says co-leader of the study, Frederick Sheedy, associate professor in Immunology in Trinity’s School of Biochemistry and Immunology.

The mice were fed a normal diet or an added small amount of β-glucan from yeast for four to 12 weeks.“Ultimately, a simple dietary supplement could help boost the immune system’s cancer-fighting ability, complementing existing treatments such as chemotherapy and immunotherapy, with the potential to improve vaccine responses and resistance to infection.”

The mice were fed a normal diet with and without an additional small amount of beta-glucan from yeast for four to 12 weeks. The researchers implanted two types of cancer cells and found that the yeast-fed group had slower-growing tumors and were smaller in overall size. 

They repeated this with obese mice that were fed a high-fat diet, and found that such diets weakened the control of tumors. The mice that consumed the beta-glucan from yeast showed a restoration of immune function, even if it had no impact on weight loss or glucose intolerance. 

Additionally, they also tested for the obese mice losing weight by returning to a normal diet and their normal body weight, switching from a high-fat to a normal diet. These mice still showed an impaired tumor control, leading the researchers to suggest that obesity may have a lasting negative impact. 

The obese mice consuming the yeast supplement and a high-fat diet had better tumor control when they lost weight, compared to those who did not receive the beta-glucan.

Helen Roche, professor in Nutrigenomics at the UCD School of Public Health, Physiotherapy and Sports Science, and the director of the UCD Conway Institute, was also one of the leaders of the study. 

She comments: “This is the first demonstration that dietary delivery of yeast beta-glucan is sufficient to induce trained immunity through reprogramming of bone marrow stem cells. Previous research required injections.”

“Crucially, this dietary intervention restores anti-tumor innate immunity in obese mice and reverses long-term immune memory defects that persist even after weight loss, a major unmet clinical challenge.”