The Relationship Between Diet and Colorectal Cancer

For the past three decades, colorectal cancer has been on the decline — likely due to better screening and greater awareness. Yet for younger adults under the age of 50, rates have more than doubled. The exact reason remains unclear; however, many experts see diet as one of the main suspects.

“Of all the environmental factors that we’re exposed to, diet is probably the number one culprit [of colorectal cancer] because dietary habits have changed dramatically over the last 25 to 40 years,” says Dr. Alessio Pigazzi, chief of colorectal surgery at NewYork-Presbyterian/Weill Cornell Medical Center and Weill Cornell Medicine. “The incidence is rising at an alarming rate, and this has stimulated a lot of interest into the possible causes of it.”

In recognition of Colorectal Cancer Awareness month, Dr. Pigazzi shares with Health Matters what foods increase your risk of colorectal cancer, what foods fight it, and the steps to take toward a healthier colon.

Long before fast food, packaged meals, and the mass-produced meat, dairy, and egg industries, colorectal cancer was actually considered rare, and it is still considered uncommon in underdeveloped, rural societies that eat leaner, healthier diets. “The so-called Western diet, which has become prevalent in industrialized nations over the last century or so, is responsible, to a large extent, for the increased incidence of colorectal cancer in our societies,” says Dr. Pigazzi.

That’s primarily due to the increased availability of sugary beverages, food loaded with unhealthy fats, and the steady rise in red meat consumption.

What you eat can affect inflammation in your bowels and gut, and inflammation is a predisposing factor for colorectal cancer development. Researchers have identified the main food substances that cause inflammation in the body and may contribute to an increased risk of colorectal cancer: Sugar, animal fats, and red and processed meats.

“What we’re trying to investigate on the more molecular level is which of these substances could be having an effect on colorectal cancer development,” says Dr. Pigazzi.

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. Part of Dr. Pigazzi’s research is to investigate whether fructose feeds tumor growth — something researchers at Weill Cornell Medicine have witnessed in animal studies thus far. “Is fructose an energy source for colorectal cancer?” asks Dr. Pigazzi. “That’s something we’re keen on finding out.”

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. “Obesity is an inflammatory state that affects the whole body,” says Dr. Pigazzi. “Obese patients have an increased risk of colorectal cancer, and there is growing evidence that it’s because these patients live in a pro-inflammatory environment.”

Red and processed meats: Bacon, salami, hot dogs, and deli meats … these, too, 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.

Plant-based diets that are high in fruits, vegetables, and whole grains (and low in animal fats and red meat) 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 as a whole.

Dr. Pigazzi follows a mostly vegetarian diet, eating fish and meat only sparingly. “I’m not here to say that eating a steak once in a while is wrong,” he says. “It’s all about ratios and enjoying it in moderation.” If you’re a frequent meat-eater, Dr. Pigazzi suggests going meatless one day a week to start.

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 best diet—and I’m a little bit biased because I’m Italian—is probably a Mediterranean diet on steroids,” says Dr. Pigazzi. “We need to increase the consumption of fruit, vegetables, legumes, nuts, and berries and try to keep the amount of red meat and animal fats to an absolute minimum.”

And the earlier in life, the better. “In my opinion, what you eat and what you’re exposed to as a child shapes your taste buds for life,” he says. “I believe we have a sweet-salty-spicy thermostat that is set early on, and it’s very difficult to reprogram your taste buds as you get older.”

Alcohol has been linked to several types of cancer, including mouth and throat, stomach, liver, pancreatic, breast, and colorectal cancer. “Reducing alcohol and not smoking always goes a long way because there is a strong association between those substances and cancer risk,” says Dr. Pigazzi. It’s OK to drink occasionally; just be sure it’s in moderation. The Centers for Disease Control and Prevention recommends no more than one drink a day for women and no more than two drinks a day for men.

According to Dr. Pigazzi, bariatric surgery has been shown to reduce the risk of colorectal and other cancers. “We’re interested in looking at ways to reduce the inflammatory response through different pathways, including different forms of bariatric surgery. If we can understand how obesity surgery like gastric bypass and sleeve gastrectomy reduces the risk of colorectal cancer and what biochemical pathways are affected, maybe we can devise nonsurgical interventions to mimic those effects.”

It is not clear whether it’s the weight loss that results in a reduced risk of colorectal cancer or whether rearranging the gastrointestinal tract, via surgery, can affect some metabolic pathways that are involved in cancer development. “Or if it’s both,” he says. “That is the interesting question. It’s something that we’re still working on in the laboratory, and that’s why it’s quite exciting.”

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. Pigazzi advises early screening — with a colonoscopy — at least 10 years prior to when your relative was initially diagnosed. “If your mother, father, or even uncle, was diagnosed at age 50, you should get screened no later than 40.”

Protect yourself from colorectal cancer and learn more about digestive health.

Alessio Pigazzi, M.D., is chief of colorectal surgery at NewYork-Presbyterian/Weill Cornell Medical Center and Weill Cornell Medicine. He also serves on Weill Cornell Medicine’s faculty. In this role, Dr. Pigazzi 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. His research is focused on minimally invasive techniques to improve recovery after cancer surgery, postoperative chemotherapy, and the relationship between diet and colorectal cancer development. Dr. Pigazzi is a fellow of the American College of Surgeons and the American Society of Colon and Rectal Surgeons, a fellow of the Society of Surgical Oncology, and a founding member of the Clinical Robotic Surgery Association.