Could pesticides on fruits, vegetables, and whole grains be contributing to early-onset lung cancer? 

A small study, presented as an abstract at the American Association for Cancer Research (AACR) Annual Meeting 2026, raises that possibility, but outside experts cautioned against drawing causal conclusions from the findings. 

The study assessed eating habits in a group of younger nonsmokers with lung cancer and found that they ate a higher quantity of fruits, vegetables, and whole grains than the general population. 

In a press release, lead investigator Jorge Nieva, MD, said the study suggests that “younger nonsmokers who eat a higher quantity of healthy foods than the general population are more likely to develop lung cancer,” though the study itself did not assess whether diet influences cancer risk.

The authors proposed a possible explanation for the counterintuitive findings: exposure to pesticide residues on food. Prior research has linked occupational pesticide exposure to higher lung cancer risk, though these exposure levels are far greater than those from dietary sources.

“We raise this as a possibility,” said Nieva, medical oncologist and lung cancer specialist with University of Southern California Norris Comprehensive Cancer Center, Los Angeles. “We didn’t study pesticides directly, but hopefully others will look into this.”

However, several outside experts who weighed in on the research were skeptical of the conclusions.

This conference abstract “provides little evidence of an association between diet and lung cancer, let alone any causal link, and offers no meaningful support for claims regarding pesticides,” said Baptiste Leurent, PhD, with University College London, in a statement from the UK nonprofit Science Media Centre (SMC).

In fact, previous research, including meta-analyses, suggests that higher fruit and vegetable intake may be associated with a lower risk for lung cancer.

“It would likely be harmful for people to avoid fruits and vegetables because of concerns for lung cancer,” commented Peter Shields, MD, emeritus professor of medical oncology at The Ohio State University, in a SMC statement. 

Rising Lung Cancer Incidence in Nonsmokers

Historically driven by tobacco use and largely affecting older men, lung cancer rates have declined overall as smoking rates have fallen. But that trend masks a notable exception: rising incidence among nonsmokers under 50, particularly women. 

To help characterize environmental exposures in young people with lung cancer, Nieva and colleagues included 166 individuals — 138 women and 28 men — diagnosed with lung cancer at age 50 or younger from the Epidemiology of Young Lung Cancer project. 

The participants completed detailed surveys covering diet, lifestyle, and exposures. Dietary quality was assessed using the Healthy Eating Index, a 100-point standardized measure of how closely diets align with federal nutrition guidelines.

Nieva and his colleagues found higher overall diet quality and intake of certain food groups compared with US averages — around 65 compared with the national reference of 58. 

On average, participants also ate more foods that can have higher pesticide residue levels. For example, patients reported higher intake of dark green vegetables, legumes, and whole grains compared with US averages. 

This study represents a “first step” toward exploring potential environmental exposures that may contribute to lung cancer in young adults, Nieva said. The next step, he said, is to assess the link by directly measuring pesticide levels in blood or urine samples from patients. 

But the research has some major limitations. 

The study did not include a control group of people without lung cancer, nor did it follow healthy people over time to see who developed the condition. The study only assessed dietary patterns in people who already had lung cancer, so “cannot tell us whether their diet played any role in causing the disease,” Justin Stebbing, professor of biomedical sciences, Anglia Ruskin University, Cambridge, England, explained in The Conversation. 

Without measuring pesticide levels in patients, or in a comparison group without lung cancer, the study cannot show that participants had higher pesticide exposures than comparable people without cancer. “ It only shows that they ate foods that, on average, can carry residues,” Stebbing wrote. 

Stephen Duffy, MSc, with Queen Mary University of London, also noted via SMC that the risk for reverse causality and confounding, which Nieva acknowledged was a “fair limitation of the study.” In other words, being diagnosed with lung cancer may have influenced participants’ lifestyle choices, leading some to adopt healthier diets.

Overall, “we have to be careful about studies providing results that were not hypothesized during study design,” Shields wrote. “Patients with lung cancer who have never smoked is rising, but still rare, and the well-known benefits for eating fruits and vegetables (and other positive lifestyle factors) far outweigh any speculation of data interpretation from this study.”

This research was supported by the Addario Lung Cancer Medical Institute, AstraZeneca, the Beth Longwell Foundation, Genentech, GO2 for Lung Cancer, and Upstage Lung Cancer. The researchers also received funding from National Institutes of Health and the National Cancer Institute. Disclosures for study authors are available in the original publication. Duffy, Leurent, Shields, and Stebbing had no disclosures.