The #1 Habit to Start Now to Reduce Your Risk of Colorectal Cancer

Colorectal cancer is one of the most common types of cancer diagnosed in the United States, and it’s on the rise among younger adults. The American Cancer Society estimates that in 2025, there will be over 154,000 new cases of colorectal cancer, with rates increasing in people under 50. While factors like age, genetics and family history play a role in your risk, there’s one impactful habit you can start today to help lower it: adding more fiber-rich foods to your diet.

“If I had to pick just one habit to lower your risk of colorectal cancer, it’s this: eat more fiber every single day,” says Shyamala Vishnumohan, PhD, an Accredited Practicing Dietitian. “But not from powders or pills—from real food like veggies, lentils, oats and whole grains,” she adds.

Research consistently links higher fiber intake with a lower risk of colorectal cancer, thanks to its hand in supporting a healthy gut microbiome and promoting regular bowel movements. Here, we spoke with cancer and nutrition experts about how fiber supports colon health, the best foods to add to your meals and simple ways to decrease your risk for colorectal cancer.

How Increasing Fiber Intake Reduces Colorectal Cancer Risk

Supports Regular Bowel Movements

One of the most well-established benefits of a high-fiber diet is that it helps keep your digestion moving and promotes regular bowel movements. Fiber—particularly insoluble fiber found in whole grains, legumes, nuts and vegetables—adds bulk to the stool and helps it pass more quickly through the colon. It also plays a role in colorectal cancer risk.

“Fiber increases the bulk of stool and reduces transit time through the colon, which means shorter contact time between potential carcinogens and the colon lining,” explains Simran Malhotra, M.D., a board-certified lifestyle medicine physician who specializes in helping women with or at high risk for cancer. 

In other words, the less time harmful substances linger in the colon, the lower the chances they have to irritate or damage the cells that line your digestive tract. Jennifer L. Armendariz, RN, an advanced oncology certified nurse practitioner, agrees, explaining, “Increasing fiber in our diet allows for more frequent bowel movements and increases the bulk of the stool. When this happens, harmful toxins and chemicals can leave the body sooner.”

Promotes a Healthy Gut Microbiome

Your gut microbiome is made up of trillions of microorganisms—both good and bad—that live in your digestive tract. This unique community plays a key role in everything from digestion to immune function. “When the balance of these microbes is off, a condition called dysbiosis, it can contribute to a higher risk of colorectal cancer,” says Armendariz. 

One of the culprits in this process is hydrogen sulfide (H₂S), a gas produced by certain gut bacteria. “In excess, hydrogen sulfide can disrupt the balance of your gut microbiome and damage the cells lining your colon, setting the stage for inflammation and disease. Elevated levels of this compound have been linked to the development and progression of colorectal cancer,” explains Armendariz.

The good news? Eating enough fiber can help tip the scales in your gut’s favor. “Fiber acts as fuel for the good gut bacteria, allowing them to thrive while reducing the activity of bacteria that produce harmful byproducts like hydrogen sulfide,” says Armendariz. Eating a high-fiber diet with plenty of fruits, vegetables, whole grains, nuts and seeds can lower the amount of hydrogen sulfide produced in the colon, reducing colorectal cancer risk.

Reduces Inflammation

Chronic inflammation has been identified as a risk factor for colorectal cancer, and the foods you eat can either promote or reduce inflammation. “Eating more fiber is one of the simplest, most powerful ways to care for your gut and reduce cancer risk,” says Vishnumohan.

“Fiber feeds your good gut bacteria that produce anti-inflammatory and anti-cancer compounds known as short-chain fatty acids,” adds Malhotra. Short-chain fatty acids help maintain the health of your gut lining, regulate immune responses and may help prevent abnormal cell growth that can lead to cancer.

Other Strategies to Reduce Colorectal Cancer Risk

Besides eating more fiber, here are four additional strategies to help lower your risk of colorectal cancer: 

• Limit or Avoid Processed Meats: It’s estimated that eating 50 grams of processed meats daily can increase your cancer risk by 18%. While you can still enjoy an occasional ham sandwich or a slice of bacon, the majority of the time, opt for minimally-processed, lean protein sources like fish, chicken breast or canned beans.
• Add Movement to Your Day: “Physical activity optimizes gut health while lowering inflammation and risk of cancer. Being physically active can also help you maintain a healthy weight,” says Malhotra. Research suggests that moderate-to-high activity levels—more than the recommended 150 minutes of moderate-intensity aerobic physical activity per week—can help reduce the risk of gut-related cancers, including colon and rectal cancers.
• Limit or Avoid Alcohol: Any alcohol consumption, even light-to-moderate intake, has been linked with an increased risk of colorectal cancer. If you don’t want to remove alcohol from your diet completely, limit intake to no more than 2 drinks per day for men and 1 drink per day for women. 
• Get Screened: For those with an average risk, the American Cancer Society recommends getting screened for colorectal cancer at age 45. If you’re at high risk for colorectal cancer, talk with a healthcare professional about getting screened even earlier. 

Our Expert Take

Colorectal cancer is on the rise, especially among younger adults. While genetics also play a role, simple, daily habits can help lower your risk. One of the most powerful habits you can start today is adding more fiber-rich foods, like vegetables, whole grains, legumes and fruits, to your plate. A high-fiber diet supports regular bowel movements, promotes a healthy gut microbiome and reduces inflammation—all of which help protect against colorectal cancer. Pair this with other healthy habits, such as staying active, limiting alcohol and routine screenings, to maintain your health well into your golden years and beyond.