Is Diet to Blame for Rising Cancer Rates Among Younger People?

Fact checked by Nick Blackmer

Key Takeaways

• Cancer diagnoses are increasing at an alarming rate among people younger than 50, according to new research.

• Gastrointestinal cancers are the fastest-growing type of cancer among younger people.

• One leading theory suggests that a diet high in ultra-processed foods may be partially responsible for high rates of early-onset cancer, especially the types that are related to the digestive system.

Researchers have warned of a rising cancer rate among people under 50 as an “emerging global epidemic,” but it’s unclear what’s causing the increase in cancer diagnoses.

In the United States, gastrointestinal cancers, including colorectal, are the fastest-growing type of early-onset cancers, according to a report published in JAMA Network Open.

One theory says diet—specifically a diet high in ultra-processed foods—is partly responsible for the increase in cancers related to the digestive system.

Ultra-processed foods are made of mostly substances extracted from foods, with additives like artificial colors and preservatives. These include hot dogs, instant ramen, cookies, and soft drinks. Some estimates have found that ultra-processed foods comprise 73% of the American food supply.

An unhealthy diet can cause systematic inflammation and insulin resistance, and it can change the gut microbiota, hence increasing the risk of colorectal cancer, according to Tomotaka Ugai, MD, PhD, a physician epidemiologist at Harvard Medical School whose research focuses on early-onset cancers.

“I think that diets really matter. Healthy diets that include plenty of fruits, vegetables, and whole grains, and that limit or avoid red and processed meats and sugary drinks can lower cancer risk,” Ugai told Verywell in an email.

Related: You Can Identify Whether Your Food Is Ultra-Processed on This New Database

Why Might Ultra-Processed Foods Increase Cancer Risk?

Ultra-processed foods are often affordable, convenient, and tasty. But having an ultra-processed diet comes with two potential problems: excess calories and insufficient fiber.

In a 2019 study, 20 volunteers were put on a diet of only ultra-processed foods or whole foods for two weeks, and then they would switch to the other diet for two more weeks. The two diets contained roughly the same nutrition profiles.

People who were on the ultra-processed diet ate about 500 more calories each day and gained two pounds. Scientists aren’t entirely sure why ultra-processed foods may result in overeating, but some have theorized that they could disrupt the gut-brain signaling that regulates appetite.

At least 13 cancers have been associated with people who have a body mass index (BMI) that’s considered overweight or obese (BMI 25 or greater), according to Francesca Castro, MS, RDN, CDN, a clinical research dietitian nutritionist at the Memorial Sloan Kettering Cancer Center in New York City.

“That has to do with increased body fatness, insulin control, hormones, inflammation, and, potentially some microbiome mechanisms as well,” Castro told Verywell.

Dietary patterns packed with ultra-processed foods also tend to contain less fiber, Castro added. But processing doesn’t mean the foods are less nutritious. For example, hummus, canned beans, and pesto are all classified as ultra-processed.

Since fiber has been shown to be protective against certain cancers, including breast and colorectal cancer, having a low-fiber diet could increase cancer risk. Castro said many Americans fall short of the recommended daily amount of dietary fiber, which is between 25–36 grams for adults.

Related: CDC: Only 1 in 10 Americans Eat Enough Produce

Swapping whole for refined grains, adding nuts to yogurt, or eating whole fruit instead of drinking juice are a few ways to get more fiber, she added.

Ultra-processed foods may not be the only culprit for a higher risk of cancer. Red meats and processed meats like bacon and sausage are also associated with an increased risk of cancers, especially colorectal cancer.

Nitrates, a chemical that’s added to many processed meats as a preservative, can increase cancer risk substantially in animals. They’re also associated with the development of gastrointestinal, prostate, and breast cancer in humans.

“Oftentimes when folks who are increasing their intake of red meat, or processed meat, or ultra-processed food, it’s usually to the detriment of more whole foods,” Castro said.

Related: Do Cancer-Fighting Foods Work?

Can Improving Your Diet Reduce Cancer Risk?

It’s impossible to guarantee that making lifestyle changes will prevent cancer. But if you’re under 50, the best cancer prevention is take charge of your health and address any controllable risk factors, according to Luke Chen, MD, a California-based medical oncologist and hematologist at City of Hope.

This means getting recommended cancer screenings, eating a balanced diet, exercising regularly, not smoking, and only drinking alcohol in moderation if at all, Chen said. Certain vaccines can also protect against cancer-causing viruses like human papillomavirus (HPV) and the hepatitis B virus (HBV).

Many cancer-prevention organizations recommend diets rich in fiber, whole grains, fruit, and non-starchy vegetables and low in added sugar, processed meats, and refined grains.

“Every individual’s cancer risk profile is different and complex, but we can say with confidence that eating a healthy diet can reduce obesity, which is linked to a wide range of major chronic health issues and cancers,” Chen said.

Although limiting ultra-processed foods, red meats, and processed meats may reduce cancer risk, the key is to think about these changes in the context of your entire dietary pattern, according to Castro.

“There’s no one food or food group that can cure cancer or reduce cancer risk,” she said.

In her own practice, Castro encourages her patients to evaluate their long-term dietary patterns and ask themselves if they’re getting enough fruit, vegetables, and fiber every day.

“When we see the headlines sometimes, we can almost punish ourselves and think of specific foods as really bad or cancer-causing,” Castro said. “It’s more about the overall dietary pattern.”

Read Next: Are Processed Foods Really That Bad?

What This Means For You

Genetics, social determinants of health, and many factors outside of our control can cause cancer. Consider speaking with a trusted healthcare provider about your specific risk for cancer. They can help you create realistic goals for dietary or lifestyle changes you could make to reduce your risk.