Probiotics and Cancer: Harnessing the Power of Your Gut Microbiome for Healing
The gut microbiome is emerging as one of the most significant areas of research in cancer prevention and treatment. Often referred to as the “forgotten organ,” the trillions of bacteria that reside in your gut are essential for digestion, immunity, and overall health.
In the context of cancer care, the microbiome plays a critical role in modulating inflammation, balancing hormones, and enhancing the effectiveness of treatments like chemotherapy and immunotherapy.
Cancer remains the second leading cause of death worldwide, with significant mortality rates linked to colorectal, breast, lung, and prostate cancers. Despite advancements in traditional treatments such as chemotherapy and radiation, these approaches often come with harsh side effects and the challenge of drug resistance. For many patients, the long-term safety and affordability of these therapies remain significant concerns.
This is where probiotics enter the conversation. These beneficial microbes offer a promising, complementary approach to cancer care. By targeting harmful cancer cells while preserving healthy ones, probiotics provide a gentler and more holistic alternative that supports the body’s natural defenses. As scientists continue to uncover the profound connection between gut health and cancer, probiotics are emerging as an invaluable tool in the fight against this disease.
While probiotics can be critical for the treatment of depression and anxiety, this article focuses on the gut microbiome in the context of cancer care. We will be exploring more about probiotics and other aspects of wellness in later posts.
Understanding Your Body's Microscopic Allies
Your microbiome is home to trillions of microorganisms living inside you, a bustling “city” teeming with activity, innovation, and purpose. This vibrant community is so large that it outnumbers your body’s own cells by a factor of ten.
But these microscopic inhabitants aren’t just squatters. They’re your body’s behind-the-scenes collaborators, working around the clock to keep you healthy. Think of your gut microbiome as a state-of-the-art chemical factory. Some bacteria, such as Lactobacillus acidophilus and Bifidobacterium bifidum, act like specialized technicians, reducing bile acid toxicity and preventing harmful enzymes—such as β-glucuronidase—from producing carcinogenic compounds.
These activities play a critical role in preventing colon cancer, as highlighted by early studies from Goldin and Gorbach.
The secret to optimal health lies in the balance of this ecosystem. When the helpful bacteria outweigh the harmful ones, your body thrives. If the scales tip the other way, problems begin to surface. This is where probiotics come into play. These beneficial bacteria are like reinforcements for your gut microbiome, helping to maintain harmony and ensuring your body’s microscopic city stays strong and healthy.
The Science Behind Probiotics and Cancer
The connection between probiotics and cancer treatment emerged from groundbreaking research by Goldwin and Gorbach, who made a remarkable discovery. They found that people with higher levels of beneficial bacteria, particularly Lactobacillus, showed a 37% lower incidence of colon cancer compared to those with lower levels. This finding raised an intriguing question: how could bacteria influence cancer development so significantly?
The answer lies in several sophisticated mechanisms:
Mechanism One: The pH Balance Effect
Your gut is like a finely tuned ecosystem, and one of its most crucial variables is pH balance—the measure of acidity and alkalinity. This balance doesn’t just affect digestion; it plays a pivotal role in cancer prevention and treatment. Imagine your gut as a swimming pool: when the pH is off, harmful organisms, like algae in a pool, can take over. Similarly, an imbalanced gut pH allows harmful bacteria, toxins, and even cancer cells to thrive.
Probiotics and pH Regulation
Here’s where probiotics, particularly Lactobacillus acidophilus and Bifidobacterium bifidum, step in as the body’s natural pH regulators. These beneficial bacteria produce lactic acid, a compound that lowers gut pH to an optimal range. This slightly acidic environment is hostile to harmful bacteria and carcinogens while supporting the growth of protective gut flora.
Reduction in Bile Acid Toxicity: Probiotics help metabolize bile acids into less harmful forms, reducing their potential to irritate the colon lining and trigger inflammation.
Cancer Cell Inhibition: In a balanced pH environment, cancer cells struggle to proliferate. Probiotics enhance this balance, creating conditions that limit cancer cell survival.
Short-Chain Fatty Acids: Another pH Ally
Probiotics are like little powerhouses that work in multiple ways to support your health. One of their key contributions is helping your gut produce short-chain fatty acids (SCFAs) like butyrate, acetate, and propionate, which are made when probiotics ferment dietary fiber. These SCFAs are essential for gut health—they lower pH to create an environment that’s unfriendly to harmful bacteria, fuel the cells in your colon, and even play a role in fighting cancer.
Butyrate, in particular, is a standout. It’s been shown to trigger cancer cell death (apoptosis) and slow their growth. In fact, studies on colorectal cancer have found that higher levels of SCFAs can reduce tumor progression and boost immune responses. In short, these tiny molecules pack a powerful punch in protecting and restoring your health.
SCFAs have several benefits:
Maintain Gut Lining Integrity: They support the health of epithelial cells, which act as a barrier against harmful substances.
Signal Immune Responses: SCFAs modulate inflammation, helping the immune system target threats like cancer cells.
Enhance pH Control: These compounds lower gut pH, reinforcing an environment hostile to pathogens and carcinogens.
Mechanism Two: The Immune System Enhancement
Another analogy to help us along is that your immune system operates as a complex, highly trained army, defending your body from threats such as infections, toxins, and cancer. Remarkably, about 70% of this immune army resides in your gut. This isn’t just a coincidence—the gut is a frontline battleground where the body interacts with the external environment through food, drink, and pathogens.
Probiotics play a critical role in fortifying this immune defense system. Acting as both trainers and reinforcements, probiotics optimize immune function in three essential ways:
1. Activating Dendritic Cells: The Scouts
Dendritic cells are specialized immune cells that act as scouts, constantly patrolling the gut for potential threats. When they identify a foreign invader, such as harmful bacteria or cancerous cells, they alert other immune cells to take action.
Probiotics enhance the activity of dendritic cells, ensuring that they are highly effective in identifying and reporting threats. For example, Lactobacillus rhamnosus and Bifidobacterium bifidum have been shown to increase the responsiveness of dendritic cells, boosting the immune system’s early warning system.
2. Strengthening T-Cells: The Special Forces
T-cells are the immune system’s elite soldiers tasked with targeting and destroying threats like viruses, bacteria, and cancer cells. Probiotics can strengthen T-cell activity in several ways:
Enhancing Cytotoxic T-Cell Function: Cytotoxic T-cells are responsible for directly attacking and killing cancer cells. Probiotics like Lactobacillus casei stimulate these T-cells, increasing their ability to identify and eliminate malignant cells.
Boosting Regulatory T-Cells: These cells prevent overactive immune responses, which can lead to chronic inflammation—a known contributor to cancer. Probiotics help maintain a healthy balance, reducing inflammation while allowing the immune system to remain alert to genuine threats.
3. Maintaining the Gut Barrier: The Fortress Walls
The gut lining acts as a barrier, preventing harmful substances such as toxins, pathogens, and carcinogens from entering the bloodstream. This barrier is critical for overall health and immune system integrity.
Probiotics strengthen this gut barrier by:
Producing Mucins: These are protective proteins that line the gut wall, making it harder for harmful bacteria or toxins to breach the barrier.
Tightening Junctions: Probiotics reinforce the "tight junctions" between cells in the gut lining, reducing the risk of substances leaking through—a condition known as “leaky gut.” Leaky gut has been associated with systemic inflammation and an increased risk of diseases, including cancer.
Competing with Harmful Bacteria: Beneficial bacteria crowd out harmful bacteria, reducing the chances of pathogenic invasion.
Probiotics do more than just give your immune system a little boost—they can actually help reshape how it works. Certain probiotic strains encourage your body to produce anti-inflammatory compounds, which can help keep chronic inflammation (a key factor in cancer progression) under control.
What’s even more fascinating is that probiotics can activate phagocytes—special immune cells that act like your body’s cleanup crew, targeting and eliminating abnormal or early-stage cancer cells. They also play a role in making cutting-edge cancer treatments, like immunotherapies, more effective. Treatments like anti-PD-L1 and anti-CTLA-4, which are revolutionizing oncology, work better when probiotics support your immune system behind the scenes. It’s like giving your body’s defenses the ultimate support team.
Mechanism Three: The Treatment Support System
Recent groundbreaking research has shed light on an astonishing truth: the success of widely used cancer treatments, including chemotherapy and immunotherapy, relies heavily on the health of your gut microbiome. In simple terms, your gut bacteria play an integral role in how well these therapies work, acting as a hidden ally in the fight against cancer.
Studies show that probiotics may help ease one of the toughest side effects—painful inflammation in the digestive tract, known as mucositis. They do this by calming down the body’s inflammatory response, reducing the levels of molecules like IL-6 and TNF-α that fuel inflammation.
What’s even more promising is that by making these treatments easier to tolerate, probiotics could help patients stick with higher doses of the therapies they need, giving them a better shot at success. It’s a simple way to bring some comfort and support during a challenging time.
Treatments like chemotherapy and immunotherapy are designed to target and destroy cancer cells, but they depend on a strong, balanced microbiome to maximize their impact. When this microbiome is disrupted—a condition known as dysbiosis—these life-saving treatments lose some of their power. It’s like trying to run a sports car on low-quality fuel: you won’t achieve the performance the engine is capable of.
Boosting Immunotherapy
Immunotherapy harnesses your immune system to attack cancer cells. Specific gut bacteria, such as Bacteroides fragilis and Bifidobacterium, have been shown to enhance the activation of T-cells—your body’s cancer-fighting warriors. A healthy microbiome supports this process, ensuring that immunotherapy works as intended. Without the right gut bacteria, this immune activation can falter.
Enhancing Chemotherapy’s Impact
Chemotherapy relies on your body’s ability to metabolize drugs efficiently. Certain gut bacteria produce compounds that enhance chemotherapy’s effectiveness while protecting healthy cells. When dysbiosis occurs, harmful bacteria may produce metabolites that interfere with these processes, reducing the treatment’s ability to kill cancer cells.
Reducing Side Effects
A balanced microbiome can also mitigate the harsh side effects of cancer treatments, such as diarrhea, fatigue, and inflammation. By maintaining gut health, probiotics and prebiotics may help patients tolerate these treatments better and recover more quickly.
Implementing Probiotics in Cancer Care
Understanding how to properly implement probiotics in cancer care requires careful consideration of several factors:
Timing: The Critical Factor
Timing probiotic administration is like orchestrating a complex dance. Dr. Jamie recommends that you work with her and the CIOFM team or a local functional medicine or naturopathic physician who focuses on the examination of the gut microbiome.
Pre-Treatment Phase: Typically probiotic supplementation at least two weeks before starting cancer treatments when possible. This is best guided by Dr. Jamie or your functional medicine care team. This preparation period allows beneficial bacteria to establish themselves and strengthen your gut's defenses.
During Treatment: Generally, probiotics are taken at specific times relative to other treatments guided by your provider and care team. For example, maintain at least a two-hour gap between probiotics and chemotherapy or other medications. This spacing prevents any potential interference while maximizing benefits.
Recovery Phase: Continue probiotic support during recovery with the guidance of your care team, as your gut microbiome helps repair treatment-related damage and supports your immune system's recovery.
Remember, we TEST, ASSESS, and DON’T GUESS!
Selecting the Right Probiotics
Not all probiotics are created equal. Different strains serve different purposes in cancer care, and that’s why testing prior to making formal treatment recommendations is important:
Lactobacillus acidophilus: This strain is particularly effective at maintaining gut pH and supporting immune function. Think of it as your first line of defense.
Bifidobacterium bifidum: This strain specializes in maintaining the integrity of your intestinal wall, like a maintenance crew repairing and strengthening your gut's protective barrier.
Bacteroides species: These bacteria have shown particular promise in enhancing the effectiveness of immunotherapy treatments, acting like force multipliers for your cancer treatment.
Akkermansia muciniphila has gained attention for its unique role in gut health and cancer care. Found in the mucus layer of the gut lining, this bacterium supports:
Gut Barrier Integrity: By promoting a strong and healthy mucus layer, Akkermansia protects the gut lining from harmful bacteria and toxins, reducing systemic inflammation associated with cancer.
Immune Modulation: It enhances immune system function, helping your body recognize and target abnormal cells more effectively.
Improved Treatment Outcomes: Research shows that patients with higher levels of Akkermansia respond better to immunotherapy treatments like anti-PD-1 and anti-PD-L1 therapies.
Medications to Avoid
Certain medications, like antibiotics and acid blockers such as proton pump inhibitors (PPIs), can unintentionally throw your gut microbiome out of balance. While antibiotics are often necessary, they can disrupt the beneficial bacteria in your gut, making it harder for your microbiome to support your immune system’s anti-tumor responses. Similarly, acid-blocking medications can change the acidity in your stomach and intestines, creating an environment that’s less friendly for the healthy bacteria your gut needs to function at its best.
If you’re undergoing immunotherapy or other cancer treatments, it’s a good idea to avoid these medications when possible—or at least manage their use carefully with your healthcare provider. Protecting your gut microbiome can go a long way in helping your treatments work more effectively and supporting your body’s natural defenses.
At CIOFM, we curate care to meet each patient’s unique needs. That’s why we recommend formal gut testing before starting treatment. This helps us uncover any underlying issues, like low stomach acid, pancreatic insufficiency, or significant gut imbalances, that might need attention. By addressing these concerns first—perhaps with herbal antimicrobials like berberine—we can clear the path for healing and then focus on replenishing your gut with the good bacteria it needs. Every step is designed to strengthen your microbiome and give your body the best chance to feel better during treatment.
Supporting Your Probiotic Protocol
Adding probiotics to your wellness routine is a fantastic step toward improving gut health and overall well-being, but it’s only part of the equation. To maximize their benefits, you need to create a gut environment that supports these helpful bacteria.
Combine probiotics with prebiotics, such as fiber-rich foods like garlic and asparagus, to nourish beneficial bacteria and promote the production of SCFAs. This combination, often referred to as a synbiotic approach, can significantly enhance gut health and may amplify the anticancer effects of probiotics.
Think of it like planting a garden—probiotics are the seeds, but they’ll only flourish if the soil, sunlight, and water are just right. Let’s explore how you can optimize your “gut garden” with the right diet and lifestyle.
Dietary Support: Feeding Your Microbiome the Right Way
Your diet plays a central role in creating the perfect conditions for probiotics to work their magic. By nourishing your microbiome with the right foods, you’re essentially giving probiotics the fuel they need to thrive.
Fermented Foods: These are rich in live, natural probiotics and can help increase the diversity of beneficial bacteria in your gut. Include options like:
Yogurt (unsweetened and with live cultures), if permitted
Kefir
Kimchi
Sauerkraut
Miso
Tempeh
Buttermilk, if permitted
Fiber-Rich Foods: Fiber serves as food for probiotics, allowing them to grow and multiply. These prebiotic foods are essential for a balanced gut:
Garlic
Onions
Leeks
Asparagus
Artichokes
Jicama
Celery
Chicory root
Apples
Blueberries
Raspberries
Blackberries
Flaxseeds
Chia seeds
Almonds
Anti-Inflammatory Foods and Spices: Chronic inflammation can disrupt your microbiome, so focus on foods that promote gut health and reduce inflammation:
Leafy greens (spinach, kale, Swiss chard)
Fatty fish (salmon, mackerel, sardines)
Leafy greens (spinach, kale, Swiss chard)
Broccoli
Brussels sprouts
Cauliflower
Sweet potatoes
Zucchini
Turmeric
Ginger
Cinnamon
Rosemary
Green tea
Matcha tea
Dark chocolate (70% cocoa or higher)
Bone broth
Additionally, probiotics can directly target carcinogens in our diets. For example, Lactobacillus strains have been shown to bind and neutralize harmful compounds like heterocyclic amines, which are found in fried or charred foods. These bacteria act as the first line of defense, reducing exposure to potential cancer triggers.
Be sure to avoid processed foods, excess sugar and carbs, and artificial sweeteners, which can feed harmful bacteria and throw your microbiome off balance.
Lifestyle Factors: Supporting Gut Health Beyond the Plate
Your daily habits are just as important as your diet when it comes to creating a healthy gut environment. Probiotics are living organisms, and their success depends on the ecosystem they inhabit.
Manage Stress: Chronic stress disrupts your gut-brain connection, leading to imbalances in your microbiome. Incorporate stress-relief practices into your day, such as:
Deep breathing exercises
Spending time in nature or “forest bathing”
Meditation or mindfulness
Gentle activities like yoga or tai chi
Get Enough Sleep: Sleep is a critical time for your gut bacteria to rebalance. Aim for 7-9 hours of quality sleep each night to support a thriving microbiome.
Stay Active: Regular exercise promotes healthy digestion and encourages the growth of beneficial gut bacteria. Simple activities like walking, cycling, or even gardening can make a big difference.
Stay Hydrated: Water is essential for every process in your body, including maintaining gut health. Staying hydrated helps probiotics function effectively and supports digestion.
Your Gut, Your Health, Your Partner in Healing
The more we learn about the gut microbiome, the more amazing it becomes. This incredible system of trillions of bacteria living inside you isn’t just about digestion—it’s deeply tied to your immune system, your hormones, and even how well cancer treatments like chemotherapy or immunotherapy work. Your gut is like a quiet partner, working behind the scenes to help your body heal and thrive.
When you nurture your gut with probiotics, fiber-rich foods, and healthy habits, you’re giving your body exactly what it needs to stay strong and resilient. Probiotics help balance the delicate ecosystem in your gut, reducing inflammation, supporting your immune system, and creating the right environment for treatments to be as effective as possible.
Your gut is a remarkable part of you, and taking care of it isn’t just science—it’s self-care. If you’re on a journey with cancer or just looking to feel your best, paying attention to your gut health is one of the most loving things you can do for yourself.
_________________________________________________________________
Disclaimer: The information provided in this blog is for educational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. The content has not been evaluated by the Food and Drug Administration (FDA) and is not intended to diagnose, treat, cure, or prevent any disease.
Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or treatment plan.
References
Gopalakrishnan, V., et al. "The Influence of the Gut Microbiome on Cancer, Immunity, and Cancer Immunotherapy." Cancer Cell, vol. 33, no. 4, 2018, pp. 570–580. Elsevier.
Goldin, B. R., and S. L. Gorbach. "The Effect of Intestinal Microflora on the Development of Colon Cancer in the Rat." The Journal of Experimental Medicine, vol. 139, no. 4, 1974, pp. 1029–1037. Rockefeller University Press.
Garrett, Wendy S. "Cancer and the Microbiota." Science, vol. 348, no. 6230, 2015, pp. 80–86. American Association for the Advancement of Science.
Zhao, LY., Mei, JX., Yu, G. et al. “Role of the gut microbiota in anticancer therapy: from molecular mechanisms to clinical applications.” Sig Transduct Target Ther 8, 201 (2023).
Zitvogel, Laurence, et al. "The Microbiome in Cancer Immunotherapy: Diagnostic Tools and Therapeutic Strategies." Science, vol. 359, no. 6382, 2018, pp. 1366–1370. American Association for the Advancement of Science, https://doi.org/10.1126/science.aar6918.
Rafter, Joseph. "Probiotics and Colon Cancer." Best Practice & Research Clinical Gastroenterology, vol. 17, no. 5, 2003, pp. 849–859. Elsevier.
Kiousi, Despoina E., et al. "The Role of the Gut Microbiome in Cancer Immunotherapy: Current Knowledge and Future Directions." Nutrients, vol. 15, no. 3, 2023, article 640. PubMed Central
Górska, A., Przystupski, D., Niemczura, M. J., & Kulbacka, J. (2019). Probiotic Bacteria: A Promising Tool in Cancer Prevention and Therapy. Current Microbiology, 76(8), 939–949.
Bedada, T. L., Feto, T. K., Awoke, K. S., Garedew, A. D., Yifat, F. T., & Birri, D. J. (2020). Probiotics for cancer alternative prevention and treatment. Biomedicine & Pharmacotherapy, 129, 110409.
