Scientists confirm direct link between ultra-processed foods and higher cancer rates

Modern convenience can carry an unseen price. A new analysis of more than 100,000 Americans finds that people who eat the most ultra-processed food (UPF) face a 41 percent higher risk of developing lung cancer than those who eat the least.

Lung cancer remains the world’s deadliest malignancy, causing an estimated 2.2 million new cases and 1.8 million deaths in 2020.. Those grim numbers make any avoidable risk factor worth close attention.

“Worse still, over the past two decades, the consumption of UPF has significantly increased worldwide, regardless of development or economic status,” said lead author Dr. Kai Wang of Chongqing University Cancer Hospital.

Lung cancer and UPF

Researchers mined the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial (PLCO), focusing on 101,732 adults aged 55 to 74.

Participants logged their diets once at enrollment, then their health was tracked for a dozen years, during which 1,706 lung cancers emerged.

Compared with the lowest quarter of UPF eaters, the top quarter had hazard ratios of 1.41 for all lung cancer, 1.37 for non-small cell lung cancer and 1.44 for small cell lung cancer.

Those figures held after accounting for smoking, overall diet quality, body size and many other variables.

Lunch meat, diet sodas and white bread were the biggest single contributors to UPF intake in this cohort. The median participant still averaged nearly three servings of these packaged products each day.

Study statisticians noted a non linear dose response curve, meaning risk climbed fastest between the first and third daily servings, then rose more slowly. Still, no amount of UPF appeared protective.

Most people eat way too much UPF

UPF already supply more than half the calories eaten at home in the United States, rising from 51 percent in 2003 to 54 percent in 2018. Globally, market growth echoes that trend as manufacturers push shelf stable snacks into every aisle.

“Greater exposure to ultra processed food was associated with a higher risk of adverse health outcomes,” reported Melissa Lane, lead author of a 2024 umbrella review. Her team linked UPF to 32 different problems, from heart disease to depression.

These products are rich in added sugars, salt, saturated fats and chemical additives while lacking dietary fiber and micronutrients. They often replace oatmeal, fruit and vegetables on busy mornings and rushed lunches.

Marketing targets all ages but especially children, creating taste preferences that can persist for decades. That lifelong exposure may magnify the cancer risk flagged in the new study.

Possible biological pathways

Poor nutrient density is only part of the story. Industrial formulation changes the food matrix, altering how nutrients and contaminants interact with human tissue.

Heating and smoking meats can produce acrolein, a reactive aldehyde also abundant in cigarette smoke. Laboratory work shows acrolein damages mitochondrial DNA, triggers mitochondrial fission and promotes cell stress in human lung cells.

Package leaching adds another layer of concern. Serum studies have linked elevated polychlorinated biphenyls to higher lung cancer odds, possibly via estrogen receptor signaling in lung tissue.

Food dyes, emulsifiers and preservatives likewise influence gut bacteria, systemic inflammation and insulin regulation. A 2023 meta-analysis tied each 10 percent rise in daily UPF calories to an 11 percent jump in cardiovascular events.

Taken together, these mechanisms suggest UPF do more than crowd out wholesome fare. They may foster a biochemical environment where rogue cells thrive.

Even non-smokers at risk

Smoking still drives most lung tumors, yet one quarter occurs in non smokers. For them, diet, air pollution and occupational exposures loom larger.

Interestingly, Dr. Wang’s subgroup analysis hinted that never smokers experienced a steeper relative risk from heavy UPF intake than current or former smokers. When baseline risk is lower, every harmful exposure carries more weight.

Passive smoke combines with UPF related contaminants such as acrolein, compounding oxidative stress. Add sedentary habits and excess body fat, and non smokers may unknowingly accumulate multiple small hits to lung tissue over time.

The study controlled for body mass index, yet obesity itself may mediate some dietary effects through chronic inflammation. Further work is needed to tease apart these overlapping pathways.

Cancer risks and UPF habits

Because participants reported diet only once, shifts in eating style went unrecorded. People who quit UPF midway, or adopted them later, all looked the same on paper.

Smoking intensity details were unavailable, leaving residual confounding possible. Yet the researchers calculated an eValue of 2.17, meaning only an undiscovered factor with a hazard ratio stronger than heavy smoking could erase the observed link.

The cohort was mostly non-Hispanic White and well educated. Findings may differ in younger, more diverse or lower income settings where UPF represents an even larger calorie share.

Longer follow up could reveal whether risk falls after dietary change, but randomized trials are unlikely for ethical reasons.

Observational evidence, mechanistic data and consistent signals across health outcomes build a persuasive narrative nonetheless.

Smart swaps for everyday meals

Swapping one sugary drink for water or unsweetened tea each day eliminates a key UPF source. Replacing lunch meat with roasted chicken or hummus on whole grain bread cuts sodium and nitrate exposure.

Frozen vegetables, plain yogurt and canned beans demonstrate that convenience need not equal heavy processing. Look for ingredient lists shorter than a tweet, and favor foods your grandparents would still recognize.

Meal planning on weekends can reduce midweek reliance on instant noodles and microwave entrées. Community programs that subsidize fresh produce make those choices easier for households on tight budgets.

Public health advocates call for front of pack warnings, advertising restrictions and taxes similar to soda levies. Whether policy shifts or personal habits change first, the Thorax findings add urgency to reducing UPF on our plates.

The study is published in Thorax.

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates. 

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–