The Relationship Between Diet and Colorectal Cancer
A leading expert discuss which foods may increase your risk for colorectal cancer and ways to protect your digestive health.
For the past three decades, colorectal cancer has been on the decline in people aged 65 years and older, according to the American Cancer Society, likely due to better screening and greater awareness. Yet for adults younger than 65, cases of colorectal cancer have increased by 0.4% for those ages 50-64 and by 2.4% in those under 50.
“The incidence is rising for colorectal cancer in younger people at an alarming rate,” says Dr. Alessandro Fichera, chief of the Division of Colon and Rectal Surgery at NewYork-Presbyterian/Weill Cornell Medical Center. “We know from research that in addition to having a genetic or familial predisposition, diet plays a major role in cancer risk.”
In recognition of Colorectal Cancer Awareness month, Dr. Fichera shares with Health Matters what foods increase your risk for colorectal cancer, what foods are healthy for your gut, and the steps to take toward a healthier colon.
The Problem with the American Diet
Long before ultraprocessed food had become a staple of the American diet, colorectal cancer was considered rare, and it is still not as common in rural societies that eat leaner, healthier diets. “It is clear a diet that is high in fat and low in fiber, is involved with many cancers, but specifically colorectal cancer,” says Dr. Fichera. “And it is proven by looking at different populations of other countries where the Western diet is not the norm, the incidence of cancer is significantly lower.”
And we are now seeing a generation of individuals who have grown up with more sugary beverages, foods loaded with unhealthy fats, and red meat, says Dr. Fichera. “In part, that may explain the increase in early-onset colorectal cancer [in people under 50 years] that we have seen in the last several years. The trend will continue unless we make some significant changes,” he says.
Foods That Increase Risk
What you eat can affect inflammation in your bowels and gut, and inflammation is a predisposing factor for colorectal cancer development. Studies have shown that the Western diet has been strongly linked to chronic inflammation. The main food substances that cause inflammation in the body and may contribute to an increased risk of colorectal cancer, researchers have found, are sugar, animal fats, and red and processed meats.
A recent study from the American Cancer Society showed that a proportion of colorectal cancer cases could be attributable to dietary factors, including 7.3% of cases linked to red meat consumption, 10.5% linked to low dietary fiber, and 12.8% linked to processed meat consumption.
Sugar: Sugar, especially processed sugar like high fructose corn syrup, is ubiquitous — it’s found in candy, sodas, and cereals, as well as breads and packaged foods. “Sugar is linked to risk of obesity and inflammation,” says Dr. Fichera. “You have to look at the type of sugar, the amount of sugar, and the balance with the rest of the diet.”
Animal fats: Animal fats can cause severe chronic inflammation, especially if eaten over a long period of time, which can also lead to obesity and type 2 diabetes. “We do know that obesity is associated with systemic, low-grade inflammation throughout the body that contributes to the direct effect of fat in the diet,” says Dr. Fichera. “There are cancers that are driven by inflammation and the correlation between inflammation and colorectal cancer is well-known and established.”
Red and processed meats: Meats like bacon, salami, hot dogs, and cold cuts can cause inflammation, obesity, diabetes, and an increased risk of colorectal cancer. The exact reason is still to be determined, but the numbers show a correlation: A study published in the International Journal of Epidemiology found that people who ate red or processed meat four or more times a week had a 20% higher risk of colorectal cancer than those who indulged in them twice a week or less.
What You Can Do To Reduce Risk
The good news is that simple lifestyle changes and staying on top of health can make a big difference.
Aim for a colorful, varied diet: Plant-based diets high in fruits, vegetables, and whole grains, are associated with a lower risk of colorectal cancer, especially fiber-rich veggies like kale, spinach, and broccoli. Leafy greens are packed with fiber and nutrients and benefit the gastrointestinal tract. There isn’t one specific vegetable that is a magic cure-all for a healthy colon. It’s more about eating a variety of nutritious foods and focusing on a colorful, plant-based diet.
“The Mediterranean diet is good because it is balanced,” says Dr. Fichera. “We need to increase the consumption of whole grains, fruit, seafood, vegetables, legumes, nuts, and berries, which the Mediterranean diet primarily consists of, and try to keep the amount of red meat and animal fats to an absolute minimum.”
Reduce alcohol intake: Alcohol has been linked to several types of cancer, including breast, mouth and throat, esophagus, voice box, and colorectal cancer, according to a recent report from the U.S. surgeon general. “Cutting both alcohol and smoking always goes a long way because there is a strong association between those substances and cancer risk,” says Dr. Fichera.
Get screened: Family history is a major determinant of colorectal cancer. Having a first-degree relative with polyps or cancer increases your risk of colorectal cancer tremendously, so having that piece of knowledge is extremely valuable. For those with a family history, Dr. Fichera advises early screening — with a colonoscopy — at least 10 years prior to when your relative was initially diagnosed. If your mother, father, or even a brother or sister, was diagnosed with colorectal cancer or a precancerous polyp at age 50, you should get screened no later than 40.
Alessandro Fichera, M.D., is the chief of the Division of Colorectal Surgery at NewYork-Presbyterian/Weill Cornell Medical Center. Dr. Fichera’s clinical and research areas include inflammatory bowel disease, minimally invasive surgery, and the prevention, treatment and management for colorectal cancer. Dr. Fichera leads a world-class team of colorectal surgeons that uses state-of-the-art technologies and innovative surgical techniques to provide patients with the very best in comprehensive colorectal care, including colorectal and anal cancer, Crohn’s disease and ulcerative colitis and other benign conditions affecting the colon, rectum and anus