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.