Mediterranean Diet May Boost Immunotherapy Outcomes

A small study found that adherence to the Mediterranean diet tended to be associated with a higher likelihood of patients with advanced melanoma responding to checkpoint inhibition. a type of immunotherapy that is commonly used for skin cancer and other solid tumors.

In particular, the Mediterranean diet is high in plant-derived foods, fiber and unsaturated fats from plant oils, nuts and fish.

The results, which were published in JAMA Oncology, showed that among 91 patients, those who followed the Mediterranean diet were more likely to see their tumors shrink from treatment (overall response rate), and typically lived longer without their disease spreading or getting worse (a statistic known as progression-free survival) than those whose eating habits were less aligned with the Mediterranean diet.

READ MORE: When It Comes to Cancer, Are We What We Eat?

“(The Mediterranean diet) is associated with gut bacteria that have been linked to immunotherapy response, said study author Laura A. Bolte, of the department of gastroenterology and hepatology at the University of Groningen and University Medical Center Groningen in the Netherlands, said in an interview with CURE®.

Of note, prior research has shown that the Mediterranean diet may also improve outcomes in prostate cancer and lower the risk for developing bladder cancer.

What is the hypothesis behind why patients who follow the

Mediterranean diet have better immunotherapy outcomes?

First, (there is) the association with the gut microbiome. The gut microbiome has been previously shown to be associated with the response to treatment with immune checkpoint inhibitors. Interestingly, many of the identified bacteria have a role in the degradation of fiber and synthesis of short-chain fatty acids (SCFA) that are known for their wide effects on the immune system. That’s how the hypothesis arose that diet — especially one that is high in fiber — could affect response to immunotherapy.

Beyond the associations with the microbiome, the Mediterranean diet is also rich in nutrients such as fiber, polyphenols, omega-3 fatty acids and vitamin C for which immunomodulatory and anti-tumor properties have been shown in functional studies.

What is the main takeaway for patients with melanoma?

Our study showed that a Mediterranean diet was associated with a better response to immune checkpoint inhibitors. Participants who scored highest on Mediterranean diet had a greater chance after 12 months that the treatment would work, i.e., that the tumor becomes smaller and will not grow or spread further.
What further research needs to be done?

Next, we want to research whether the influence of diet on immunotherapy response is driven (or) mediated by the gut microbiome.

Where are we in the research field, and what can be said so far:

While we need larger studies across multiple geographies paired with higher resolution of food components to offer patient-tailored advice, we can already inform patients starting treatment with immune checkpoint inhibition about the potential importance of their diet.

The traditional principles of Mediterranean diet remain the most widely studied and recommended dietary guideline. This dietary advice is already provided in many other disease contexts such as for diabetes and immune-mediated diseases, and in public health information aimed at disease prevention. Patients can be referred to these resources.

There are also dietary guidelines for patients with cancer, like from the (National Cancer Institute) and (American Cancer Society) that overlap with the Mediterranean diet. They emphasize consumption of fruits, vegetables, legumes, whole grains, nuts, seeds and pay attention to caloric and protein needs while limiting processed foods.

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