Can Gut Bacteria Influence Colorectal Cancer Risk?
August 2, 2025
These days, gut health is getting a lot of attention, and for good reason. The bacteria living in your digestive tract (called your gut microbiome) do a lot more than help with digestion. They’re also connected to your immune system, mood, and even your risk for certain diseases, including colorectal cancer (CRC).
At the Alabama Colon & Rectal Institute in Birmingham, we want everyone to have the information they need to protect their health. Anyone can take simple steps to care for their gut and reduce their risk of colon cancer.
What Is the Gut Microbiome?
Your gut is home to trillions of bacteria. Most of them are helpful. They break down food, help you absorb nutrients, support your immune system, and even produce important vitamins like B12 and K. Some research also shows these bacteria send signals to your brain, which may affect your mood and mental health.
When the microbiome is balanced, it supports your overall health. But when too many harmful bacteria take over—or when there aren’t enough good ones—that balance is lost. This is called dysbiosis, and it can lead to inflammation, digestive issues, and even a higher risk of CRC.
Gut Bacteria and Cancer: What’s the Link?
Colorectal cancer is the third most common cancer in the U.S., and rates have been rising in people under 50. Scientists are learning more about how gut bacteria play a part in that risk. Here’s what they’ve found:
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Inflammation
Some harmful bacteria irritate the colon’s lining. That can trigger chronic inflammation, which damages cells and may lead to growths or tumors over time. -
DNA Damage
Certain bacteria produce toxins that can damage DNA inside colon cells. When your body tries to fix that damage, it can make mistakes—mistakes that sometimes lead to cancer. -
Weak Immune Response
A strong immune system helps detect and destroy abnormal cancer cells early. But when your gut is out of balance, your immune cells may not respond as well as they should. -
Low Bacterial Diversity
A healthy gut has a wide variety of bacteria. Less diversity has been linked to markers that may increase cancer risk, though scientists are still studying how this works.
Boost Your Gut Health and Cancer Prevention
The good news? You have a lot of control over your gut health. Here are easy, everyday changes that can help protect your colon and boost your overall well-being:
Eat More Fiber
Fiber feeds the healthy bacteria that live in the human gut. When they digest it, they create substances that lower inflammation and protect your colon lining.
Good sources of fiber include:
- Fruits and vegetables
- Whole grains
- Beans and lentils
Fiber goals:
- Women: at least 25 grams a day
- Men: at least 38 grams a day
Add Fermented Foods
Yogurt with live cultures, kefir, kimchi, miso, sauerkraut, and kombucha can all help replenish beneficial bacteria in your gut.
Cut Back on Processed and Red Meat
A diet high in red or processed meat has been linked to higher rates of colon cancer. Try swapping some of those meals for fish, poultry, or plant-based proteins.
Drink Plenty of Water
Staying hydrated helps keep your digestive system moving and gives your gut bacteria a healthy environment to thrive in.
Get Moving
Exercise supports a diverse gut microbiome and promotes regular bowel movements. Even 30 minutes of walking most days can make a difference.
Be Smart About Antibiotics
While antibiotics are sometimes necessary, they can also wipe out good gut bacteria. Only take them when prescribed, and follow up with probiotic-rich foods when you’re done.
What About Probiotic Supplements?
Probiotic supplements can be helpful, especially after illness or antibiotics, but they’re not always needed. Most people do better getting probiotics from food. If you’re considering a supplement—especially if you have a digestive condition—talk to your proctologist first.
Who Should Pay Extra Attention to Gut Health?
Gut health matters for everyone, but some people may be at higher risk and should be especially mindful, including:
- Adults over 45
- Anyone with a family history of colorectal cancer
- People with Crohn’s disease or ulcerative colitis
- Those with long-lasting digestive issues like bloating, constipation, or changes in bowel habits
- LGBTQ+ individuals who may not always receive routine or inclusive care
We encourage everyone to ask questions and seek care that meets their needs, because early action saves lives.
Frequently Asked Questions About Colorectal Cancer And Gut Microbiome
How often should I get screened for colon cancer?
Most people should start regular screenings at age 45. If you have a family history or other risk factors, your doctor may recommend starting earlier.
Can diet really change my gut bacteria?
Yes. Your gut microbiome responds quickly to changes in what you eat. Adding fiber and cutting back on processed foods can start to make a difference in just a few weeks.
Is it too late to improve my gut health if I’m older?
Not at all. It’s never too late to start eating better, staying active, and making choices that support your gut and immune system.
What symptoms should I watch for?
If you’re dealing with bloating, blood in your stool, frequent constipation or diarrhea, unexplained weight loss, or sudden changes in bowel habits, it’s time to check in with a doctor.
The Alabama Colon & Rectal Institute Is Here for You
At the Alabama Colon & Rectal Institute, we’re proud to offer expert care that’s compassionate, respectful, and focused on you. Our team understands how personal and sensitive conditions of the colon and rectum can be, and we make sure you feel seen and heard at every step.
If you’re due for a screening or struggling with colorectal issues, we’re here to help!
Problems With Your Gut?—Schedule a Visit with AL Colon & Rectal
Protecting your gut is one of the best ways to care for your body and possibly lower your cancer risk. This June, we’re here to support you with expert care that’s grounded in science and delivered with compassion.
Contact us today online or by calling (205) 458-5000 to schedule a consultation and explore the best treatment options for your specific needs.