Ultra-processed foods are industrially manufactured products that often contain additives such as flavours, colours, and preservatives. Examples include soft drinks, packaged bread, ready meals, confectionery, and salty snacks. These foods make up about 60% of the calories consumed in the United States.
Researchers analysed data from more than 100,000 adults (50,187 men and 51,545 women) who participated in the U.S.-based Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Participants, with an average age of 62.5 years, reported their eating habits and were followed for over 12 years.
During that time, 1,706 people were diagnosed with lung cancer. The study found that those who ate the most UPFs (about six servings per day) had a 41% higher risk of lung cancer compared to those who ate the least (about half a serving per day).
Most of the cases (86.3%) were non-small cell lung cancer (NSCLC), while the remaining 13.7% were small cell lung cancer (SCLC).
Possible Explanations
Researchers suggest several reasons why UPFs might increase cancer risk:
- Poor nutritional quality compared to whole foods like fruits and vegetables.
- Additives such as glutamate and carrageenan that may disrupt gut and lung health.
- Harmful contaminants from processing and packaging.
Experts Urge Caution
Health experts caution that the study shows an association, not proof that UPFs directly cause lung cancer.
Dr. Nilesh Vora, a cancer specialist in California, said: “The study generates a compelling hypothesis that needs further research to validate the claim.”
Katrina Brown, senior cancer intelligence manager at Cancer Research UK, also noted that other factors, such as smoking and workplace exposures, may have influenced the results. “In the lung cancer space, it’s impossible to draw firm conclusions without very close adjustment for smoking,” she said.
Broader Health Risks of UPFs
This study adds to growing evidence linking UPFs with poor health outcomes. Previous research has associated high UPF intake with obesity, type 2 diabetes, heart disease, and cancers such as breast and ovarian cancer.
Brown added: “We wouldn’t say this study sounds huge alarm bells, but it reinforces the recommendation to reduce processed food consumption and replace it with healthier alternatives.”
Experts agree that the most effective way to lower lung cancer risk remains quitting smoking, but reducing UPF consumption could also support better overall health.
