An alarming trend has emerged in my medical practice in recent years: I’m seeing more and more young adults with colorectal cancer.

When I began practicing as a family physician 21 years ago, I never saw patients in their 40s and 50s with the disease, much less ones in their 30s. Now, I diagnose two to three people in those age groups every year.

On the heels of National Colorectal Cancer Awareness Month, I want to share my experience with other physicians and warn young adults, in particular, of the dangers of this type of cancer that can start with a change in bowel habits and evolve into large tumors and late-stage disease by the time it’s diagnosed.

Studies confirm what I see in my practice just outside Indianapolis, Indiana. Colorectal cancer rates are rising among young people. Adults born around 1990 have twice the risk of colon cancer and four times the risk of rectal cancer compared with adults born around 1950, according to a study published by the National Cancer Institute. And this is not a trend that’s projected to let up. A 2021 JAMA study estimates colorectal cancer will be the top cause of cancer-related deaths for those aged 20 to 49 in the coming years.

What’s responsible for this, I believe, is the increasingly poor diet of Americans, consisting of more processed foods, fast foods, and red meat than ever before.

The good news is the risk of colorectal cancer can be mitigated for those willing to clean up their diets. Specifically, I recommend my patients eat a whole food, plant-based diet high in fiber and devoid of meat and processed foods.

Research has shown that plant-based diets reduce the risk of colon cancer. For example, this study, published online in BMC Medicine, showed men who ate the most plant-based foods had a 22 percent reduced risk of colon cancer compared with those who ate the least.

Studies have found that a diet high in red meat increases the risk of colorectal cancer. For example, one study published in the Journal of Nutrition and based on food questionnaires from more than 50,000 Black female participants showed a 33 percent increased risk for late-onset colorectal cancer for every 100 grams (3.5 ounces) of red meat eaten per day.

Plant foods, high in fiber, can reduce the contact of potential carcinogens with cells lining the digestive tract. The fiber causes food to travel faster through a person’s digestive system. This also reduces intestinal cells’ contact with bile acids, which can promote cancer growth. Fruits, vegetables, whole grains, and legumes also provide phytonutrients and antioxidants, which can help repair damaged cells and reduce cancer risk.

Aside from what studies show, can a plant-based diet reduce real-life colorectal cancer risk? My husband, Marc, I believe, is living proof that it can.

A “meat-and-cheese” guy who ate no vegetables before he married me, Marc had his first colonoscopy at 50 and was found to have four large precancerous polyps. He immediately began a whole-food, plant-based diet. Fast forward three years to a recent repeat colonoscopy, and he had zero polyps with no intervention except a change in diet. The gastroenterologist was amazed. He told us that never happens.

In addition to eating a whole food, plant-based diet, I recommend patients maintain a healthy weight and get regular colorectal cancer screenings. I recommend starting colonoscopies at age 45 or 10 years before your nearest first-degree relative is diagnosed with colon cancer.

Because of the rise in colorectal cancer cases and deaths among young adults, the physicians at Yale Medicine are asking patients younger than 45 to talk to their doctors about symptoms of constipation, rectal bleeding, or sudden changes in bowel movements. I agree and encourage my patients to do the same.

It’s time for adults in this country, including young adults, to reflect on the data on colorectal cancer and work to turn around the troubling trend by adopting a whole-food, plant-based diet.

With this kind of food overhaul, everyone can reduce their risk of developing colorectal cancer, heart attacks, diabetes, and stroke.

Victoria Othersen is a family physician.