Scientists are exploring whether something as simple as a dietary ingredient could help repair immune problems linked to obesity.
A new mouse study suggests that a fiber taken from yeast can influence the body’s immune-cell factory and improve its ability to respond to cancer.
Researchers from Trinity College Dublin and University College Dublin carried out the work, which was published in Cell Reports. The study examined yeast beta-glucan, a natural substance already used in some foods and dietary supplements.
The finding is interesting because obesity affects much more than body weight. It can change hormones, metabolism and inflammation throughout the body, and these changes can also alter the immune system.
People need a healthy immune system to fight infections, but immune cells also play an important role in cancer. They can recognize abnormal cells, attack them and help prevent some tumors from growing unchecked.
Obesity can make these defenses less effective. Even after weight loss, some immune changes may remain, suggesting that the body can keep a kind of memory of its earlier metabolic state.
The Irish research team asked whether yeast beta-glucan might help reset some of this immune memory. Rather than focusing only on mature immune cells already circulating in the blood, they looked deeper into the bone marrow, where many immune cells are first produced.
Bone marrow contains early cells that can develop into several types of blood cells. If these starting cells are changed, the effects may continue as they produce new immune cells over time.
To test the idea, the researchers gave mice either a normal diet or a high-fat diet. Some mice also received yeast beta-glucan in their food for between four and 12 weeks.
The animals were later challenged with different cancer cells, including cells linked to colon, skin and breast tumors. The researchers then studied how strongly the animals’ immune systems responded.
Mice that received the yeast ingredient developed stronger anti-cancer immune responses. The researchers found signs that beta-glucan had changed early bone marrow cells, creating effects that continued in the immune cells produced from them.
Scientists describe this process as trained immunity. It means that parts of the immune system can be prepared by an earlier exposure so that they react more strongly when they encounter a later challenge.
The study found a particularly notable effect in obese mice. Yeast beta-glucan appeared to restore some of the anti-tumor immune activity that obesity had weakened.
The supplement also helped with immune problems that continued after obese mice lost weight. This suggests that changing body weight alone may not always be enough to undo every lasting effect obesity has on immune function.
Professor Helen Roche said the work provides the first evidence that eating yeast beta-glucan can produce this type of immune training by changing stem and early-stage cells in bone marrow. Earlier research generally used injections to produce comparable effects.
That difference matters because a food-based treatment would be much simpler than an injected therapy. The beta-glucan tested in the research is a food-grade product that is already commercially available.
The researchers therefore see a possible path toward studies in humans. Future trials could investigate people living with obesity or other conditions that weaken normal immune responses.
There is also interest in whether such an approach could support existing cancer care. Modern cancer treatment can include surgery, chemotherapy, radiation and immunotherapy, which helps the immune system recognize or attack cancer more effectively.
A dietary supplement that improves certain immune responses could potentially complement these treatments. But that possibility remains theoretical until well-designed clinical trials show that the approach is safe and useful in patients.
This is the main limitation of the new research. Mice are valuable for studying biological mechanisms, but their immune systems, metabolism and cancers are not identical to those of humans.
It would therefore be premature to conclude that yeast beta-glucan prevents cancer or improves cancer survival in people. The study also does not establish that commercially available supplements should be taken as a cancer treatment.
The strongest message from the research is more modest but still important. It shows that a dietary substance can reach far enough into the immune system to change how early immune cells develop, at least in mice, and may help overcome some lasting effects of obesity.
If future human studies confirm these findings, the work could open a new way of thinking about nutrition and immunity. For now, it offers a promising scientific lead rather than a proven cancer therapy.
Source: Trinity College Dublin and University College Dublin.
