Scientists at the Peter Doherty Institute for Infection and Immunity in Australia have discovered how gut bacteria help the body’s immune system fight one of the deadliest forms of skin cancer — melanoma.
The new study, published in the journal Immunity, explains why melanoma patients who eat more dietary fiber and maintain a healthy balance of gut bacteria tend to respond better to cancer immunotherapy.
When we eat foods rich in fiber, such as fruits, vegetables, grains, and legumes, our gut bacteria digest these fibers and produce small molecules called metabolites. Among these are short-chain fatty acids, which turn out to have a powerful effect on immune cells that fight cancer.
The research, conducted by scientists from the Doherty Institute, the Peter MacCallum Cancer Center, and Monash University, shows that these bacterial by-products can boost the function of killer T cells — the body’s natural cancer-fighting soldiers.
Dr. Annabell Bachem, a Senior Research Fellow at the University of Melbourne and co-first author of the study, said the findings help explain how gut health is directly linked to immune strength.
She said that while it was already known that a high-fiber diet improves responses to cancer treatment, the exact mechanism was unclear until now. Her team discovered that when gut bacteria break down fiber, they produce metabolites that act as both messengers and fuel for the immune system.
These short-chain fatty acids essentially ‘charge up’ T cells, giving them more energy and helping them work harder to recognize and kill melanoma cells.
Professor Sammy Bedoui, senior author of the study and head of the laboratory at the Doherty Institute, said this discovery may explain why some melanoma patients respond well to immunotherapy while others do not.
Immunotherapy is a groundbreaking treatment that activates the immune system to attack cancer, but it doesn’t work for everyone. According to Professor Bedoui, T cells can become exhausted and lose their ability to destroy cancer cells over time.
The study showed that the molecules made by gut bacteria can help prevent this exhaustion, keeping T cells active for longer. He explained that patients with advanced melanoma who eat more fiber and have a diverse and healthy gut microbiome tend to have better outcomes from immunotherapy.
This new understanding could lead to new strategies that combine diet, probiotics, or gut-targeted drugs with standard cancer treatments to boost their success rate. The team also worked closely with Professor Shahneen Sandhu, a medical oncologist at the Peter MacCallum Cancer Center, to compare their findings with real patient data.
They found that melanoma patients who responded well to immunotherapy also had gut bacteria that produced more short-chain fatty acids. This connection strengthens the theory that gut health plays a vital role in how the immune system fights cancer.
Professor Sandhu said that these insights could help doctors design new approaches to improve treatment for melanoma and potentially other cancers. Future therapies may include personalized diets or supplements that promote beneficial gut bacteria alongside immunotherapy to enhance its effects.
The researchers emphasized that this discovery began with a simple scientific question — how do T cells get their energy and how does the gut influence their function? By following that question, they uncovered a key link between nutrition, gut health, and the body’s ability to fight cancer.
In conclusion, this study highlights the incredible connection between what we eat and how our immune system performs. A balanced diet high in fiber doesn’t just support digestion; it may also empower our immune cells to fight cancer more effectively.
As research continues, patients may one day benefit from treatments that combine medical therapy with dietary support, offering a more natural and holistic way to combat melanoma.
If you care about skin health, please read studies about eating fish linked to higher risk of skin cancer, and Vitamin B3 could help prevent skin cancers.
For more health information, please see recent studies about vegetable oil linked to spread of cancer, and results showing Vitamin D could help treat skin inflammation.
The study is published in Immunity.
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