Could a Plant-Based, High-Fiber Diet Improve Cancer Survival?

Key Takeaways:

• A diet rich in fiber could positively impact gut bacteria and potentially enhance cancer survival rates, according to a study led by Dr. Jennifer Wargo from the University of Texas MD Anderson Cancer Center.
• Fiber nurtures certain types of gut bacteria that generate short-chain fatty acids with anti-inflammatory and anti-tumor activities, potentially affecting how cancer patients respond to immune checkpoint inhibitors.
• In the study, melanoma patients who consumed a high-fiber diet (at least 20 grams per day) from fruits, vegetables, beans, and whole grains had a higher response rate to immunotherapy than those who consumed less fiber.
• Contrary to fiber, probiotic supplements did not show benefits for patients and potentially even interfered with the response to immune checkpoint inhibitors. Further research is needed to explore this.
• Optimal gut health may be achieved by eating a diverse plant-based diet and fermented foods. However, access to nutritious whole foods could be a hurdle for some individuals.

Intriguing findings from initial research carried out on lab mice and melanoma patients suggest that consuming a diet rich in fiber could positively impact gut bacteria and subsequently enhance cancer survival rates. However, the use of probiotic supplements appeared to counteract these beneficial effects. Further studies are required to fully explore this relationship.

The Influence of Gut Microbiome on Health

The gut microbiome, referring to the mixture of trillions of bacteria and other microbes that live mainly in our gastrointestinal tract, plays a pivotal role in several body functions. They participate in crucial physiological processes, including metabolism, immune defenses, nutrient synthesis, and even brain function.

Dr. Emeran Mayer, a professor at the University of California, Los Angeles, and author of the book “The Gut-Immune Connection,” who has no involvement in the new study, highlighted that gut bacteria contribute to the “education and training” of the immune system. The interactions between gut bacteria and immune system cells are continuous.

The Potential Role of Fiber in Cancer Cures

Fiber also affects the composition of the gut microbiome. Certain types of bacteria, those generating short-chain fatty acids exhibiting anti-inflammatory and anti-tumor activities, are sustained by fiber. The gut microbiome has been found in previous research to affect how cancer patients respond to immune checkpoint inhibitors.

Such drugs, including Keytruda and Opdivo, are used in the treatment of various cancer types. They increase the ability of the immune system’s T-cells to detect and attack cancer cells by removing a specific immune “brake.” The big question is whether a diet rich in fiber could influence the response of patients to these treatments.

A Deeper Look into Melanoma Patients and Their Diets

To explore this, a team led by Dr. Jennifer Wargo, of the University of Texas MD Anderson Cancer Center in Houston, analyzed the diets of 128 patients with advanced melanoma, a particularly deadly form of skin cancer.

The study found that patients who consumed adequate dietary fiber (at least 20 grams per day) from fruits, vegetables, beans, and whole grains had a higher response rate to immunotherapy than those who consumed less fiber. Seventy-six percent of the high-fiber diet group responded positively to immunotherapy, meaning their tumors regressed or remained stable for at least six months, compared to sixty percent of those consuming a low-fiber diet.

Fiber Vs. Probiotic Supplements

No such benefit was found among the patients who took probiotic supplements. Interestingly, the best response rate of 82% was observed among patients consuming a high-fiber diet without taking probiotics. This suggests that fiber might play a beneficial role in cancer treatment, although this needs further confirmation.

Subsequent studies on lab mice with melanoma tumors further supported the potential harm of probiotic supplements, which appeared to interfere with their response to immune checkpoint inhibitors. Meanwhile, a high-fiber diet slowed tumor growth in the mice and seemed to enhance their T-cell activity. However, this improvement was not observed in mice devoid of gut bacteria, suggesting that the effects of a high-fiber diet are likely mediated through the gut microbiome.

Implications for Cancer Patients

People often look for ways to regain control and support their treatment after a cancer diagnosis. While some might turn to supplements, Wargo recommends discussing such usage with healthcare providers considering the findings from this study.

Further research is required to confirm the potential benefits of fiber, according to Mayer. He notes that food plants, the primary source of dietary fiber, also contain other nutrients, such as polyphenols, which might also play a role. A clinical trial that tests the effects of adding dietary fiber to patient diets is currently underway. “This is just the beginning of this line of research,” Dr. Wargo commented, adding that it could have far-reaching implications for people with various types of cancer, and possibly everyone.

The question on whether specific dietary regimes can enhance the body’s response to infections or vaccines, like the flu and COVID-19, is particularly intriguing.

Eat a Diverse Diet for a Healthy Gut

For those desiring to maintain a healthy gut microbiome, diversifying plant food intake and consuming fermented food like yogurt, fermented cottage cheese, kimchi, and sauerkraut is recommended. These foods have been linked to greater variety in gut bacteria. However, access to these nutritious whole foods might be a hurdle for some individuals, Mayer cautioned.

Further Information:

For more details on nutrition and the microbiome, check out the resources provided by the Harvard School of Public Health here.