A large U.S. cohort study has found that individuals consuming the highest levels of ultra-processed foods face a significantly greater risk of developing lung cancer, even after adjusting for smoking and other factors.

Research published in the journal Thorax analyzed data from more than 101,000 participants in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. Over an average follow-up period of 12 years, researchers identified 1,706 incident cases of lung cancer, including 1,473 cases of non-small cell lung cancer—the slower-growing form—and 233 cases of the more aggressive small cell variant.

Participants in the top quartile of ultra-processed food consumption, adjusted for energy intake, showed a 41% higher risk of lung cancer compared with those in the lowest quartile (hazard ratio 1.41). The associations held for both non-small cell (37% higher risk) and small cell (44% higher risk) subtypes.

Ultra-processed foods typically include items formulated with multiple industrial processes and additives, such as preservatives, emulsifiers and artificial flavors. Examples in the study ranged from ice cream, packaged sauces and confectionery to soft drinks, ready-made burgers, pizza and processed meats. On average, the energy-adjusted ultra-processed food consumption was 2.8 servings per day, with lunch meat contributing 11.1% to total UPF intake, diet or caffeinated soft drinks 7.3%, and decaffeinated soft drinks 6.6%, the study found. UPFs are described as nutritionally poor, with high energy density, low fibre, fewer micronutrients, and excessive sugars, sodium, fats and additives.

Examples: 

• Sugar-sweetened beverages
• Processed meats
• Packaged snack cakes & pastries
• Instant noodles & boxed meals
• Frozen prepared pizzas & entrées
• Sugary breakfast cereals
• Flavored/sweetened dairy products
• Reconstituted meat products
• Packaged refined breads & buns
• Processed cheese products

The findings build on prior evidence linking ultra-processed foods to a range of adverse health outcomes, including cardiovascular disease, type 2 diabetes and reduced life expectancy. In the U.S. and Britain, such foods comprise more than half of daily caloric intake for many individuals.

“You can’t say from this study that UPFs cause cancer as it’s observational, so we’re looking at associations, not direct effects. But it does strengthen the case for looking more closely at the food environment many people are living in, where UPFs are cheap, convenient, and heavily marketed, making them a go-to for many,” Rob Hobson, author of Unprocess Your Family Life, told The Independent.

“That might mean cooking more from scratch where possible, adding in more whole foods like vegetables, beans and grains, or just becoming more aware of how often UPFs show up in your day,” Hobson added. “It’s not about being perfect, it’s about balance and understanding how your food choices could be supporting or undermining your long-term health.”