Intestinal environment and various diseases

Understanding the Relationship Between Gut Bacteria and Cancer

To gain a deeper understanding of the relationship between gut health and cancer, it is essential to understand the role of gut bacteria. We will examine how gut bacteria function within the body and influence cancer development. To gain a deeper understanding of the relationship between gut health and cancer, it is essential to understand the role of gut bacteria. We will examine how gut bacteria function within the body and influence cancer development.

The Role of Gut Bacteria and the Mechanism of Cancer Development

Gut bacteria not only aid in food digestion but also play a role in maintaining cellular health and regulating immune function. Specifically, they help reduce the risk of stomach and colon cancer by breaking down harmful substances produced in the large intestine and suppressing inflammation. When the gut environment becomes disrupted, harmful bacteria proliferate and carcinogens accumulate more easily. Therefore, gut health practices incorporating dietary fiber and fermented foods are key to cancer prevention.

Gut Microbial Diversity and Cancer Risk

Gut microbial diversity is essential for maintaining health. The coexistence of diverse bacteria helps maintain immune balance, suppress inflammation, and promote the elimination of carcinogens. Studies report that when specific harmful bacteria become dominant, the risk of colorectal cancer and esophageal cancer increases. To maintain diversity, regularly incorporating dietary fiber, fermented foods, and unrefined grains into your diet is effective.

Fundamentals of Cancer Immunotherapy and Its Relationship with the Gut Environment

Cancer immunotherapy is gaining attention as a new treatment option for cancer. Let’s understand its basic mechanism and how it works.

Basic Concepts of Cancer Immunotherapy

Cancer immunotherapy is a treatment that activates the patient’s own immune system to attack cancer cells. Specific approaches include immune checkpoint inhibitors (e.g., nivolumab [Opdivo] and pembrolizumab [Keytruda]), cancer vaccine therapy, and CAR-T cell therapy. These are gaining attention as novel approaches that enhance treatment efficacy by adjusting the immune system to recognize and attack cancer cells as “enemies.” Unlike traditional anticancer drugs, these therapies are characterized by fewer side effects and the potential for sustained efficacy. To maximize treatment effectiveness, ongoing dialogue and understanding with your physician are essential. It is crucial to proceed only after fully understanding the treatment options and associated risks.

The Impact of Gut Bacteria on Immunotherapy

Gut bacteria act as regulators of immune function and also influence the efficacy of cancer immunotherapy. Specifically, it has been reported that in a gut environment rich in beneficial bacteria, T cell activity increases, leading to improved response rates to immune checkpoint inhibitors. T cells are a type of white blood cell that function as the immune system’s command center and attack force, playing a role in directly attacking cancer cells and virus-infected cells. Among these, “killer T cells” recognize and destroy cancer cells, while “helper T cells” coordinate the overall immune response. Recent research has revealed that beneficial bacteria present in the gut, such as those belonging to the Bacteroides genus, promote the maturation and activation of T cells. Studies specifically examining the gut bacteria of Japanese individuals have also suggested that certain bacterial species may influence the effectiveness of immunotherapy.

Overview of Immune Checkpoint Inhibitors

Immune checkpoint inhibitors are drugs that release the immune system’s “brakes” imposed by cancer cells, enabling T cells to attack the cancer. Compared to conventional chemotherapy, they are characterized by a clear target and fewer side effects. Recently, their application has expanded to lung cancer, melanoma, colorectal cancer, and others, with new effects also being reported in clinical studies.

Specific methods for improving gut health

The specific methods for improving gut health involve nurturing gut bacteria and maintaining a healthy diet.

Dietary Fiber and Gut Microbiota Development

Dietary fiber serves as food for gut bacteria, particularly beneficial bacteria, and is key to maintaining a healthy gut environment. Brown rice, barley rice balls, steamed vegetables (such as burdock root, carrots, and lotus root), and fruits like kiwi and apples are effective sources. Incorporating these into your daily diet activates bifidobacteria and balances your gut flora. Chewing thoroughly and eating slowly also promotes digestion and absorption, aiding the growth of gut bacteria.

The Effects of Fermented Foods and the Role of Lactic Acid Bacteria

Lactic acid bacteria found in fermented foods increase beneficial bacteria in the gut and contribute to activating the intestinal flora. Foods like miso soup (made with additive-free miso), kimchi, pickled vegetables in rice bran, and vegetables pickled in salted koji are easy to incorporate into your diet and simple to maintain regularly. Additionally, amazake (made without added sugar) is often called “drinkable IV fluid” and is rich in lactic acid bacteria and enzymes. Consuming small amounts of these foods daily will steadily improve your gut environment.

The Impact of Dietary Habits on Health Maintenance

Maintaining good health starts with a nutritionally balanced diet. It’s important to include staple foods, main dishes, and side dishes, aiming for at least 350g of vegetables and 200g of fruit daily. For example, grilled salmon, spinach ohitashi, miso soup with tofu, and mixed grain rice make an ideal meal. Utilizing the Ministry of Health, Labour and Welfare’s “Dietary Balance Guide” helps you practice a daily diet that’s gentle on the gut and minimizes nutritional imbalances.

The Importance of Gut Health in Cancer Prevention

The state of the gut environment is closely linked to cancer prevention. We will examine specifically how gut bacteria influence immunity and cancer risk.

The Impact of Gut Environment on Cancer Prevention

Gut health is deeply connected to immune function and plays a crucial role in cancer prevention. Maintaining a balanced gut microbiota suppresses inflammation and the production of harmful substances, thereby reducing the risk of cancer cell development. For instance, incorporating fiber-rich root vegetables and fermented foods promotes the growth of beneficial bacteria. Additionally, sufficient sleep and stress management contribute to improving gut health. The key to gut health lies in the daily accumulation of dietary choices and lifestyle habits.

The Relationship Between Clinical Data and Gut Microbiota

The relationship between gut bacteria and cancer has been the focus of numerous clinical studies. One study comparing colorectal cancer patients with healthy individuals found a gut flora characterized by a reduced ratio of beneficial bacteria and a predominance of harmful bacteria. These findings suggest that the state of the gut environment significantly influences disease onset and progression. Maintaining a balanced gut microbiota is a crucial step in preventive healthcare.

The Latest Research and the Future of Gut Microbes

Research into cancer treatments focusing on gut bacteria is advancing daily. Here, based on the latest research findings, let’s explore its potential and challenges.

Research Trends in Gut Microbiota and Cancer Treatment

Research on the role of gut bacteria in cancer treatment is advancing worldwide. For example, it has been confirmed that the efficacy of immune checkpoint inhibitors increases in patients harboring specific gut bacteria. Additionally, the existence of bacterial strains that mitigate the side effects of anticancer drugs has been reported. These findings suggest the potential for future precision medicine tailored to each patient’s gut environment. In recent years, gut bacteria have increasingly become recognized not merely as supporting players, but as key factors holding the key to cancer treatment.

The Potential and Prospects of Fecal Microbiota Transplantation

Fecal microbiota transplantation (FMT) is a treatment that replaces disrupted gut flora with healthy intestinal bacteria. It is gaining attention not only for refractory intestinal diseases but also for its potential relationship with cancer treatment. Research has reported that FMT may enhance treatment efficacy, particularly in patients who are unresponsive to anticancer drugs or immunotherapy. While currently largely in the research phase and facing challenges regarding safety and the sustainability of its effects, it is a field with great promise for future clinical application. A new medical horizon is expanding, viewing gut bacteria as a “therapeutic resource.”

Summary

The Clinical Research Society for Fecal Microbiota Transplantation has already performed over 690 cases of a new “fecal microbiota transplantation” that avoids antibiotics and minimizes patient burden. If you suffer from abnormal fermentation of intestinal bacteria, are interested in the state of your own gut microbiota, or are interested in fecal microbiota transplantation, please contact a clinic near you.

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Supervisor: Dr. Hideaki Shima, Ph.D. in Agriculture (Symbiotics Co., Ltd.)