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Why Are More Young People Getting Colon Cancer? Gastroenterologist Shilpa Ravella Explains

Colon cancer was once rare in people under 50, but over the past three decades, it’s become increasingly common. A 2017 study found that people born in 1990 are twice as likely to develop colon cancer as people born in 1950, and the American Cancer Society released a report earlier this year underscoring the uptick, noting that from 2011 to 2019, colorectal cancer rates increased by about 2% per year in people under 50. That shift has prompted researchers to look closer at the ways these cancers manifest in young people and identify potential warning signs. To understand what’s behind the concerning trend, we spoke with gastroenterologist Shilpa Ravella, MD, assistant professor of medicine at Columbia University Medical Center and author of A Silent Fire: The Story of Inflammation, Diet and Disease. Ravella breaks down the four red flags young people should be aware of when it comes to colorectal cancer, the role inflammation plays in forming and fueling cancer, and how you can reduce your risk. Jump to a specific topic below, or read on for the full conversation.

I want to start off by asking you about the rising rates of colon cancer in younger people. Is this just a matter of better screening?

Shilpa Ravella: This has been on my mind quite frequently lately, as I’m seeing more and more patients being diagnosed with not just colorectal cancer but other cancers, and patients in their 20s and 30s with no apparent risk factors being diagnosed with early-onset colon cancer, which is colon cancer that develops when one is less than 50. We’ve seen an increase in the incidence of early-onset cancer over the last few decades. It’s an emerging global epidemic. While there are genetic factors that affect cancer incidence, some of the recent research argues that early-onset cancer is largely related to diet, exercise, and other lifestyle factors, including environmental exposures like pollutants, etc.

I came across a 2022 study by researchers at Brigham and Women’s Hospital in Boston that was published in Nature Reviews Clinical Oncology. The study stated that cancer cases among those under 50—including colon, breast, esophagus, kidney, liver, and pancreatic cancer—have risen worldwide since around 1990, likely due to the increasingly sedentary lifestyles and Western diets that are filled with processed foods, sugary beverages, and alcohol use. These researchers point out that enhanced screening alone doesn't account for the noted increase in cancer incidence. So I do think that a large part of this is driven by our environment [and lifestyle].

Given the rising rates, should people start getting colonoscopies at a younger age than previously recommended?

SR: Currently, the guidelines support getting a screening colonoscopy at the age of 45. But I do recommend being vigilant about your body and trying to stay aware of any symptoms or signs that may be concerning. There was a new study published just a couple of months ago, in the Journal of the National Cancer Institute. The researchers looked at over 5,000 early onset colon cancer cases to identify red flags that occurred before diagnosis.

They found that between three months and two years before the diagnosis date, there were four red flags that stood out—signs and symptoms that were tied to an increased risk of early onset colon cancer. One is rectal bleeding. Anytime you have blood in the stool, or rectal bleeding, you should definitely see a physician. The others are diarrhea, iron-deficiency anemia, and abdominal pain. Of course, some of those are a little vague—many of us have abdominal pain at times—but it's a reminder to keep an eye on your body. Don't dismiss any of these gastrointestinal symptoms, because they could point to something more insidious. The early recognition of red flags can potentially help with early detection and a timely diagnosis of early onset colon cancer.

If younger patients are concerned about their colorectal health—say, because they’re experiencing one of those red flags—how would you recommend they talk to their health care provider?

SR: I think it's important to establish what your baseline is. Know your own body, so that when something is off from your baseline, you can advocate for yourself as a patient and say, “Hey, I really feel like something's off,” and push to have your symptoms taken seriously. If your symptoms are concerning, you should obtain a referral to see a gastroenterologist.

Which foods and dietary patterns have been linked to colorectal cancers?

SR: One of the big ones is red and processed meats, which have been tied to increased colorectal cancer risk in epidemiologic studies. Those should definitely be minimized or entirely avoided. And cooking any sort of meat at high temperatures can create chemicals that raise your cancer risk.

Also, diets that are low in fruits and vegetables and fiber. We are a fiber-deficient nation: 95% of Americans don't meet the RDAs of fiber in this country. That's stunning, because we need to go beyond the RDAs, and yet most of us are not even meeting RDAs. Fiber has been tied to so many different positive health outcomes, [including] decreased risk of colorectal cancer and other cancers. Fiber is also one of the most important nutrients that helps to manipulate our immune system. It calms inflammation in the body. It can do this directly, or it can do this through the germs in our gut. So inflammation is one potential mechanistic pathway by which a high-fiber diet can actually influence chronic disease.

Food is so much more than fuel. There is a language being spoken at the intestinal border and also throughout the body that relates to your immune system. Your immune cells are conversing with your [gut] microbes at all hours of the day. Eating the right types of foods helps to fuel those conversations that are essential for your health.

What is the connection between inflammation and cancer?

SR: Normally, our immune system tries to get rid of cancer as it would germs. But inflammation—whether it's low-level, hidden inflammation or overt inflammation—can actually fuel cancer. It can affect all of its life stages, from the initial genetic or epigenetic influences that transform normal cells into malignant ones, to the continued growth and spread of cancer throughout the body. For example, my patients with inflammatory bowel disease who have chronic, uncontrolled inflammation also carry a higher risk of developing cancer.

Of course, it’s important to keep in mind that not all areas of the body with an increase in inflammation have a marked increase in cancer risk. For example, increased inflammation in joints or the brain carries little increased cancer risk. But generally, being inflamed … is tied to a higher risk of various cancers.

Inflammation is an important component of the tumor microenvironment, as well. Whether [inflammation] shows up before or after the cancer, it can affect all its life stages, from helping to initiate cancer in the body to fueling the cancer’s continued growth and spread.

How does exercise impact inflammation?

SR: We have dozens of clinical trials across age groups that show that exercise can help to dampen chronic, hidden inflammation. It does this in a variety of ways. One of the most important and obvious ways is to melt belly fat, which is a marker for visceral fat—the highly inflammatory fat that surrounds our inner abdominal organs. But even in the absence of weight loss, exercise can decrease the number of immune cells that infiltrate fat tissue. So it’s not just about losing weight. When you exercise, you initiate beneficial physiological processes that decrease inflammation and decrease the risk of chronic disease. Exercise is very important.

What’s the No. 1 step young people can take to reduce their risk of colon cancer?

SR: Increase the quantity and the diversity of plant foods in the diet. In addition to fiber, plants contain many other nutrients that can help to manage inflammation. … You want to be eating whole and minimally processed plant foods. Whole and intact grains tend to be much better for the gut microbes than heavily processed flours. … There are studies that show that simply altering the diversity of plants in your diet without changes in quantity can actually help to decrease inflammation. … We really need to push ourselves to explore the supermarket and to fill our plates with a variety of plant foods.

Ravella’s debut book, A Silent Fire: The Story of Inflammation, Diet and Disease, is available here.

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About the Author

Courtney Davison

Courtney Davison is Forks Over Knives’ managing editor. A writer and editor on a wide range of subjects, she co-wrote a nationally syndicated advice column from 2016 to 2018 and co-authored the 2018 book Ask Me Anything: A Year of Advice from Dear Annie. She is a longtime vegan and in her free time enjoys trying new recipes and spending quality time with her cats. Find her on LinkedIn.
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