When most people think of lung cancer, smoking is the first risk factor that comes to mind. But new research suggests your diet might be putting you at greater risk than you think—especially if it includes a high amount of ultra-processed foods.

Lung Cancer: The World’s Deadliest Cancer

According to the World Health Organization (WHO), lung cancer is the number one cause of cancer-related deaths globally. It claims more lives each year than any other type of cancer.

In the U.S., it ranks as the second most common cancer for both men and women (excluding skin cancer). However, it remains the leading cause of cancer death—accounting for roughly 1 in 5 cancer fatalities, reports the American Cancer Society (ACS). That’s more than breast, colon, and prostate cancer deaths combined.

Lung cancer comes in two primary forms:

• Small cell lung cancer (SCLC) – more aggressive
• Non-small cell lung cancer (NSCLC) – slower-growing, but more common (87% of cases in the U.S.)

Traditionally, the biggest risk factor for lung cancer has been smoking. About 85% of lung cancer cases globally are linked to tobacco use. Other contributors include secondhand smoke, air pollution, and carcinogens like radon, asbestos, and diesel fumes.

But now, researchers are warning that ultra-processed foods (UPFs) could be a surprising new risk factor.

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Ultra-Processed Foods Linked to Higher Lung Cancer Risk

A large study published in the journal Thorax found a strong link between ultra-processed food consumption and increased lung cancer risk.

Researchers analyzed data from more than 100,000 participants aged 55 to 74, collected between 1993 and 2001. Participants’ diets were recorded using food frequency questionnaires and tracked through 2018 for cancer diagnoses and deaths.

Foods were divided into four categories:

• Unprocessed or minimally processed
• Processed culinary ingredients
• Processed foods
• Ultra-processed foods (UPFs)

Common UPFs included:

• Ice cream and frozen yogurt
• Salty snacks and baked goods
• Instant noodles and store-bought sauces
• Soft drinks and hot dogs

The top three UPFs consumed were:

• Lunch meat (11%)
• Diet/caffeinated soft drinks (7%)
• Decaffeinated soft drinks (nearly 7%)

The Findings Are Alarming

Compared to those who consumed the least UPFs, people who ate the most had:

• 41% higher risk of lung cancer overall
• 37% higher risk of NSCLC
• 44% higher risk of SCLC

Researchers noted that industrial food processing can alter nutrient absorption and introduce harmful chemicals. Some of these toxic byproducts—like acrolein, which is also found in cigarette smoke—appear in grilled meats and caramel products. Packaging materials may also contribute to risk.

“These findings need to be confirmed by other large-scale longitudinal studies in different populations and settings,” the study authors wrote. “If causality is established, limiting trends of UPF intake globally could contribute to reducing the burden of lung cancer.”

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UPFs Are Also Tied to Early-Onset Colon Cancer

This isn’t the first time ultra-processed foods have been tied to cancer risk.

A 2023 study in the journal Nutrients linked UPFs to the rising rates of colon cancer among Americans under 50. Researchers cited the typical Western diet—high in fat and low in fiber—as a cause of gut imbalance (dysbiosis), inflammation, and immune suppression, all of which can create an environment for cancer to grow.

A second study published in Gut backed these findings. According to Dr. Timothy Yeatman of USF Health Morsani College of Medicine, “Cancer is like a chronic wound that won’t heal. If your body is living off daily ultra-processed foods, its ability to heal that wound decreases due to inflammation and immune suppression.”

Final Takeaway: Rethink What’s on Your Plate

While smoking remains the biggest risk factor for lung cancer, this new evidence suggests that your diet matters more than you might expect. Reducing your intake of ultra-processed foods may not just improve your overall health—it could save your life.