High-fiber diet could improve immunotherapy for melanoma patients

Credit: formulatehealth/ Wikimedia.

Researchers from the Center for Cancer Research studied the effects of a diet rich in fiber—including fruits, vegetables, and legumes—and the use of probiotic supplements on response to immune checkpoint blockers.

They found that a diet rich in fiber may help some people being treated for melanoma respond to immunotherapy treatment by influencing the gut microbiome.

Among patients with advanced melanoma who underwent immunotherapy with immune checkpoint blockers, those who consumed at least 20 grams a day of dietary fiber survived the longest without their disease progressing.

In contrast, the use of probiotic supplements appeared to lessen somewhat the effectiveness of immune checkpoint blocker regimens.

Probiotics are live microorganisms typically consumed as a supplement to improve gut health.

Immunotherapy with immune checkpoint blockers helps restore the immune system’s natural ability to recognize and kill tumor cells.

These drugs have been transformative in melanoma, improving how long some people with advanced disease live, sometimes by years.

However, for many patients, immune checkpoint blockers fail to stop their tumors from growing.

Several studies have suggested that the composition of the bacteria in the gut may influence the response to immunotherapy.

In the current study, the team looked at the composition of fecal microorganisms (the gut microbiota), dietary habits, and probiotic supplement use among patients who were being treated for advanced melanoma with immune checkpoint blockers.

They found that those who reported consuming at least 20 grams of dietary fiber per day (an amount the researchers designated as “sufficient” for the purposes of this study) lived longer without their cancer progressing than those who consumed less dietary fiber.

Every 5-gram increase in daily dietary fiber intake corresponded to a 30% lower risk of progression of the disease.

The findings suggest that the impact of dietary fiber and probiotics on the gut microbiota is only part of the bigger picture.

Many factors can affect the ability of a patient with melanoma to respond to immunotherapy.

However, from these data, the microbiota seems to be one of the dominant factors.

The data also suggest that it’s probably better for people with cancer to receive immunotherapy not to use commercially available probiotics.

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The study was conducted by Spencer CN et al., and published in Science.