Consuming a diet high in ultra-processed foods (UPFs) is associated with a significantly increased risk of developing lung cancer, according to a major new study. The research adds to a growing body of evidence linking UPFs, which constitute more than half of the average diet in both the UK and US, to a host of serious health conditions.
The Stark Link Between Diet and Cancer Risk
Published in the respiratory journal Thorax, the study analysed data from over 155,000 participants aged 55 to 74, drawn from US cancer screening trials. Participants' diets were assessed, and they were tracked for up to 12 years. During this period, 1,706 new cases of lung cancer were diagnosed.
After adjusting for influential factors like smoking and overall diet quality, the results were striking. Those who ate the most ultra-processed foods were 41% more likely to be diagnosed with lung cancer compared to those who ate the least. The risk increase was 37% for non-small cell lung cancer (NSCLC) and 44% for small cell lung cancer (SCLC).
What Counts as an Ultra-Processed Food?
While there is no single definition, UPFs typically undergo multiple industrial processes and contain additives, preservatives, and flavour enhancers. They are often ready-to-eat or heat. The study highlighted several common culprits in high-consumption diets:
- Lunch meats (making up 11% of the UPF intake)
- Diet, caffeinated, and decaffeinated soft drinks (over 14% combined)
- Packaged bread, baked goods, and salted snacks
- Instant noodles, shop-bought soups and sauces
- Margarine, confectionery, and sweetened fruit drinks
- Restaurant or shop-bought items like hamburgers, hot dogs, and pizza
This research builds on a 2024 BMJ review that connected UPF consumption to 32 harmful health effects, including higher risks of heart disease, type 2 diabetes, mental health issues, and early death.
Understanding the Implications and Expert Advice
The researchers acknowledge the study's observational nature, meaning it shows association, not direct causation. Factors like smoking intensity, which was not fully detailed, could play a role. However, they point to the low nutritional value of UPFs and their high levels of salt, sugar, and unhealthy fats as likely contributors to disease risk.
"Industrial processing alters the food matrix, affecting nutrient availability and absorption, while also generating harmful contaminants," the study authors noted. They highlighted substances like acrolein, found in some grilled foods and sweets, which is also a toxic component of cigarette smoke.
Speaking to The Independent, nutritionist Rob Hobson, author of Unprocess Your Family Life, emphasised a balanced approach. "You can’t say from this study that UPFs cause cancer... But it does strengthen the case for looking more closely at the food environment," he said.
Hobson advises against demonising individual items and instead recommends practical, sustainable shifts. "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," he suggested. "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."
With lung cancer causing an estimated 1.8 million deaths globally in 2020, the study concludes that limiting UPF consumption could be a crucial step in curbing the disease's impact worldwide.
