How does nutrition affect colorectal cancer risk?

Two young adults being playful in the outdoor kitchen while preparing a healthy meal.


Find out what foods fuel colorectal cancer and what to eat for a healthy digestive tract.


By James Nitzkorski, MD, Surgical Oncology and Colorectal Surgery, Nuvance Health


“What’s your favorite food?” This is such a common question! Food plays a major role in most of our lives. Gatherings from holidays and date nights to lunch breaks with co-workers revolve around food. With so many social reasons to eat and choices for how we dine, it is no wonder the basic need for food is not always top of mind — we need nutrients to grow, heal and maintain our bodies. We are what we eat!


What happens when the foods we eat do not contribute to these vital functions, and in turn, increase cancer risk? In particular, research shows a link between diet and colorectal cancer risk — which is occurring more frequently in people under age 50. 


Find out what foods get a gold star when it comes to lowering colorectal cancer risk and which foods should take a time out.



What is the link between nutrition and cancer?


The connection between diet and cancer risk is complex. It is rooted in the fundamental biology of how our bodies process the foods we consume. What we eat can influence inflammation, hormone levels, our microbiome and cell growth within our bodies. Let’s break these down.


Research shows a strong link between chronic inflammation and many types of cancer. Chronic inflammation can damage DNA. Each cell in your body has DNA. DNA damage can cause cells to grow out of control and lead to cancer in a part of the body. If it is not caught early, it can spread to other parts of the body.



Some cancers use hormones to grow, including breast cancer and prostate cancer. Regularly eating foods that affect hormone levels can affect your risk for these cancers.


Show your cells some love — they are, after all, the basic building block of all living things! Regularly eating foods that promote healthy cells can help you manage cancer risk, because cancer occurs from abnormal cells.



Some foods contain carcinogens (cancer-causing) or promote their production during digestion, leading to DNA damage over time. For example, processed meat is in Group 1 carcinogenic, according to the International Agency for Research on Cancer (IARC).


Conversely, certain nutrients can protect cells from damage and support immune function, creating a natural defense system against cancer development. Research shows these nutrients mainly come from plant-based foods such as fruits, vegetables, whole grains and beans.


How does diet affect colorectal cancer risk?


Diet plays a critical role in colorectal cancer. Colorectal cancer includes colon cancer and rectal cancer. These develop when cells grow out of control in the large intestine, which is part of the digestive tract. It is no wonder why diet has such a profound impact on cancer of the digestive health system. Here are some important reasons why.



Healthy foods promote a smooth digestive system


Your digestive health system processes everything you eat. Food travels down from your mouth through your esophagus into your stomach. Your stomach breaks down food, your pancreas breaks down carbohydrates, fats and proteins to use for fuel and ultimately your large intestine breaks down remaining nutrients and waste products. Your body removes waste products through your rectum and anus. Your liver, gallbladder and small intestine are working away, too. Complex to us, your body is made for digesting food and delivering nutrients to your body for energy.


You can see how foods that are difficult for your body to digest or are carcinogenic can wreak havoc on your colon and rectal health. Processed foods are difficult for your body to digest and can cause inflammation, so we recommend eating a diet full of plant-based and natural whole foods as often as possible. Processed means the food has been altered from its original state. Ultra-processed foods include chips, fried foods, deli meats, bacon, hotdogs and sausages, candy, sweetened cereal and more — and should be avoided.


Cool it with inflammatory foods to lower colorectal cancer risk


Speaking of inflammation, inflammatory bowel disease (IBD) is a risk factor for colorectal cancer. IBD includes Crohn’s disease and ulcerative colitis. Generally, anti-inflammatory foods can help manage IBD symptoms, including quelling inflammation in the colon. These foods include fatty fish like salmon, mackerel and tuna, and fruits such as blueberries and strawberries.



What are the best foods to lower colorectal cancer risk?


Plant-based foods

There is no single food that can lower or eliminate colorectal cancer risk. But mounting research shows a link between a plant-based diet combined with fruits, vegetables and whole grains and lower colorectal cancer risk. This type of diet can also be called the Mediterranean diet. You can also incorporate healthy fats (monounsaturated and polyunsaturated) from avocados and olive oil to name a couple of foods.


Fiber-rich foods

High-fiber foods, such as fruits, vegetables, legumes and whole grains, are essential to keeping your digestive system running smoothly. Eating enough fiber can help you avoid constipation and limit the time cancer-causing substances spend in contact with intestinal cells. Fiber-rich foods also help you stay fuller longer and can aid in weight management. Obesity is a risk factor for colorectal cancer because your body is in a constant state of inflammation.





Additionally, foods rich in antioxidants and omega-3 fatty acids, like berries, fatty fish, leafy greens, nuts and seeds can protect against cell damage and support overall health.




Water is essential to your digestive health. Water aids in digesting food and removing waste from your body. 



What diet is associated with an increased risk of colorectal cancer?


Diets high in processed meats (think bacon and hot dogs), red meat and foods loaded with added sugars and fats have been linked to an increased risk of colorectal cancer. The frequency and quantity of these foods in your diet can significantly affect your risk level. Regular consumption of processed meats, for example, has been associated with a higher risk of colorectal cancer, underscoring the importance of moderation and dietary balance.


You can still enjoy a hot dog on the Fourth of July. Just aim to choose foods grown from the Earth versus processed and packaged in a factory most of the time.


How to eat healthy


Here are some tips for incorporating healthy foods into your daily meals:


Plan your meals: We have all been here — dinnertime after a long day and the drive-thru is ever so tempting. Take time each week to plan meals that include a variety of fruits, vegetables, whole grains and lean proteins (if you eat meat) and are ready to enjoy throughout the week. Plus, plan meals you look forward to and tempt you even more than pizza delivery.


Cook at home: Preparing meals at home gives you control over ingredients and helps you avoid the hidden sugars and fats often found in pre-packaged and restaurant foods. Find a way to make it fun, whether cooking with your family or remotely with your best friend. Take a picture or video and share your creation on social media.


Choose whole foods over processed: Whenever possible, opt for whole, unprocessed foods. They are not only healthier but often more satisfying.


Experiment with plant-based meals: Try incorporating a few plant-based meals into your week. These can be both delicious and nutritious.


Increase fiber gradually: To avoid digestive discomfort, slowly add more fiber to your diet over several weeks. Plus, drink plenty of water as you add fiber. 


Set realistic meal goals: Setting realistic diet goals can keep you motivated to eat healthy. 


Find healthy alternatives: Experiment with healthy alternatives to satisfy your cravings. For example, use carrot chips instead of potato chips to enjoy salsa, or bake “brownies” only with oatmeal, peanut butter, bananas and berries (Find the recipe on Instagram).


Treat yourself: Make meal prep and eating healthy foods fun. Stream a show or listen to music or a podcast during meal prep, and package prepared meals in colorful and fun containers.



How to manage your colorectal cancer risk


While diet plays a pivotal role in colorectal cancer risk, it is one piece of the puzzle. You can also manage your colorectal cancer risk by regularly exercising, limiting alcohol consumption and not smoking. Alcohol and smoking are toxins to the body and cause inflammation.


It is also important to know your personal and family health history. Your doctor may recommend colonoscopy screenings or other surveillance if you have an increased risk due to:

  • Irritable bowel syndrome, including Crohn’s disease and ulcerative colitis
  • Inherited cancer risk, including Lynch syndrome
  • A first-degree relative (parent, sibling, child) with a colon polyp or cancer
  • Your ethnic background, including African American and Ashkenazi Jewish descent


The United States Preventive Services Task Force (USPSTF) recommends people at average risk of colorectal cancer start colonoscopy screenings at age 45. We used to recommend colonoscopy at age 50, but the guidelines changed because more people are being diagnosed with colorectal cancer at a younger age than ever before. 


A gastroenterologist performs colonoscopies to see inside your large intestine and look for any abnormalities. They can remove precancerous polyps before they have a chance to turn into cancer. They can also detect cancer earlier before it has spread. Talk with your primary care physician about alternatives to colonoscopy screenings if you cannot or prefer not to have one. While colonoscopy screenings are the gold standard, any screening is better than no screening.


Ready for a colonoscopy screening? Find a gastroenterologist near you.


The bottom line: Adopting a diet that prioritizes whole, nutrient-dense foods and limits processed meats, sugars and unhealthy fats can reduce your risk of colorectal cancer. By making informed dietary choices today, you can set the foundation for a healthier tomorrow. Remember, small changes can lead to significant health benefits over time.