The Link Between Your Diet and Colorectal Cancer
More than 154,000 Americans will receive a colorectal (colon) cancer diagnosis this year, making it the fourth most common cancer affecting men and women according to the American Cancer Society (ACS). It’s also one of the most preventable cancers.
“What you eat and drink, as well as lifestyle choices like exercise and smoking, are risk factors you can control to lower your risk of colorectal cancer,” says Andrew Chan, MD, MPH, a Mass General Brigham Cancer Institute gastroenterologist.
Dr. Chan leads research focused on cancer prevention and exploring why colorectal cancer rates are increasing, especially among younger people. Here, he shares the foods and drinks you can cut back on—and the ones to stock up on—to help protect your colon.
Foods that increase colorectal cancer risk
A Western diet (also known as the standard American diet) is high in foods that can increase your risk of colon cancer. These foods include:
Red meats and processed meats
The ACS lists red meat (beef, pork, and lamb) and processed meats (bacon, hot dogs, and deli meats) as probable carcinogens (cancer-causing substances). These meats may damage the normal colon lining, leading them to become cancerous cells that quickly multiply and grow.
Red meat is also high in heme iron, which may cause cellular damage. Cooking red meat at high temperatures, like broiling, charring, or frying, may generate even more cell-damaging compounds. Nitrates and nitrites, preservatives found in many processed meats, may also be carcinogenic.
The American Institute for Cancer Research (AICR) estimates that eating one hot dog or two slices of deli meat every day raises your risk of colorectal cancer by 16%. The AICR recommends eating no more than 3 portions of 4- to 6-ounce servings of cooked red meat (the size of a deck of cards) every week. Try to consume processed meat more sparingly, if at all.
Ultra-processed foods
Ultra-processed foods have lots of added sugar, salt, saturated fats, and flavor enhancers designed to make them taste better. They also have preservatives to help them last longer. Processed foods include chips, crackers, baked goods, and shelf-stable meals that you can quickly eat with minimal prep time. They also include sugary drinks like sodas, energy drinks, and fruit juice.
“Processed foods are made with ingredients you wouldn’t typically use at home,” says Dr. Chan. “They’re high in calories but lack nutritional value.” More than half of the calories in an average American’s diet come from ultra-processed products. Ongoing research, including a study led by Dr. Chan, suggests that a diet high in ultra-processed foods may be one reason that colorectal cancer is on the rise among younger adults.
Eating too many high-calorie, high-fat processed foods can also contribute to obesity, which increases colon cancer risk. “Ultra-processed foods and excess weight cause inflammation that changes cells,” says Dr. Chan.
In addition, healthy bacteria in your intestines, which are part of your gut microbiome, may break down ingredients in processed foods into harmful substances. A Mass General Brigham study suggests that certain gut microbiome changes can cause precancerous colon polyps.
Alcoholic drinks
All alcoholic drinks contain ethanol, which can be broken down into potential carcinogens. Alcohol also affects your health by causing inflammation and changing your gut microbiome. The link between alcohol and cancer is so clear that the ACS cites it as one of the most avoidable causes of cancer.
The ACS recommends not drinking alcohol at all. At most, men should have no more than two drinks per day and women no more than one drink per day. One drink is a 5-ounce glass of wine, 12-ounce beer, or 1-ounce shot of liquor. Your risk of colorectal cancer increases the more alcohol you drink. “Heavy drinkers and binge drinkers seem to be especially at risk for colorectal cancer,” says Dr. Chan.
Foods to prevent colorectal cancer
A diet high in anti-inflammatory foods, such as the Mediterranean diet, is one of your best defenses against cancer. “These meal plans are high in plant-based foods, whole grains, healthy fats, and lean meats like fish and chicken,” says Dr. Chan. “They provide antioxidants, fiber, and omega-3 fatty acids that calm your immune system and improve gut health.”
Anti-inflammatory foods have a positive effect on your entire body. In addition to lowering cancer risk, cholesterol, and blood sugar, they’re also good for your heart health. When you’re making your grocery list of inflammation-fighting foods, be sure to include:
High-fiber foods
Fiber in vegetables, fruits, whole grains, beans, and legumes feeds healthy gut bacteria, acting as prebiotics that reduce intestinal inflammation. Studies show that getting 90 grams of whole grains a day (that’s half a cup of cooked oatmeal or brown rice) may lower colorectal cancer risk by up to 17%.
Low-fat dairy products
Research shows calcium and vitamin D may help protect against colorectal cancer. A Mass General Brigham study found that consistently eating yogurt can cause helpful gut microbiome changes that protect against colorectal cancer. Other studies show that drinking an 8-ounce glass of milk every day may lower colorectal cancer risk by up to 10%.
Other ways to prevent colorectal cancer
In addition to dietary changes, it’s important to know your colorectal cancer risk factors and make other changes like not smoking, maintaining a healthy weight, and being physically active.
“One of the most important actions you can take is to get colorectal cancer screenings as recommended by your health care provider,” says Dr. Chan. “With a colonoscopy, we can remove colon polyps before they become cancerous and treat colorectal cancer early when it’s most curable.”
