People who consume the highest amounts of ultra-processed foods face a 41% greater risk of developing lung cancer compared to those eating the least, according to research published in the respiratory journal Thorax.
The findings, based on data from over 100,000 Americans followed for 12 years, suggest that limiting consumption of ready-to-eat meals, processed meats, and sugary drinks could help reduce the global burden of the world’s most common cancer.
Lung cancer claimed 1.8 million lives worldwide in 2020 alone, with 2.2 million new cases diagnosed that year, the researchers noted.
The study analysed data from 101,732 participants (50,187 men and 51,545 women, average age 62) drawn from a broader pool of 155,000 people aged 55-74 who completed detailed dietary questionnaires as part of major US cancer screening trials between 1993 and 2001. Researchers tracked cancer diagnoses until 2009 and deaths until 2018.
Foods were classified into four processing categories: unprocessed or minimally processed; containing processed culinary ingredients; processed; and ultra-processed. The ultra-processed foods examined included lunch meats, ice cream, fried foods, breakfast cereals, instant noodles, shop-bought soups, soft drinks, and fast-food items like hamburgers and pizza.
Participants consumed an average of nearly three servings daily, ranging from 0.5 to 6 servings. The most frequently consumed ultra-processed foods were lunch meat (11% of intake), diet or caffeinated soft drinks (just over 7%), and decaffeinated soft drinks (nearly 7%).
During the follow-up period, 1,706 people developed lung cancer-1,473 cases of non-small cell lung cancer and 233 cases of small cell lung cancer. Even after accounting for smoking habits and overall diet quality, those in the highest consumption group showed significantly elevated risks.
The increased risk was 37% for non-small cell lung cancer and 44% for small cell lung cancer among heavy ultra-processed food consumers.
“Over the past two decades, consumption of ultra-processed foods has significantly increased worldwide, regardless of development or economic status,” the authors wrote. This rise may be driving global increases in obesity, cardiovascular disease, and cancer, they added.
The researchers suggest ultra-processed foods may crowd out protective foods like whole grains, fruits, and vegetables from people’s diets. Industrial processing also alters food structure, affecting how nutrients are absorbed whilst generating harmful compounds like acrolein-found in grilled sausages and caramel sweets and also present in cigarette smoke.
Food packaging materials may also contribute to health risks, the study noted.
The authors acknowledged their findings require confirmation through additional large-scale studies across different populations before definitive conclusions can be drawn about causality.
“If causality is established, limiting trends of ultra-processed food intake globally could contribute to reducing the burden of lung cancer,” they concluded.