A USC-led study of 187 young adults with lung cancer found a link between healthier diets and higher disease rates in non-smokers under 50, with researchers suggesting pesticide residues on fruits and vegetables may be a contributing factor.
The study, presented at a scientific conference and not yet peer-reviewed, analyzed patients diagnosed before age 50, most of whom had never smoked. Participants who reported eating more fruits, vegetables, and whole grains — measured via the Healthy Eating Index — showed a higher likelihood of having early-onset lung cancer compared to the general population.
Researchers emphasized the finding shows only an association, not causation, and does not mean fruits and vegetables are harmful. Instead, they hypothesize that pesticide residues on conventionally grown produce could explain the unexpected link, noting that non-organic crops often carry higher pesticide levels than processed foods or animal products.
Women made up 78% of the study group, reflecting a broader trend of rising lung cancer rates among young non-smoking women in the U.S., even as overall lung cancer incidence declines due to falling smoking rates. The tumors in these patients were often driven by genetic pathways like EGFR fusions, which are more common in non-smokers.
The study did not measure actual pesticide levels in participants’ bodies or food, nor did it compare pesticide exposure between those with and without cancer. Experts caution against changing dietary habits based on the preliminary findings, stressing that decades of large-scale research consistently present plant-rich diets reduce cancer risk.
For more on this story, see Study links fruit and vegetable-heavy diet with increased lung cancer risk in young non-smoking women.
The authors say the results should prompt further investigation into environmental contaminants in food, not deter people from eating fruits and vegetables, which remain linked to lower rates of heart disease, stroke, and several cancers in long-term studies.
Large longitudinal studies have repeatedly found that higher fruit and vegetable intake correlates with lower lung cancer risk, especially among smokers, forming the basis of public health guidelines. These studies, which follow hundreds of thousands of people over time, are considered far more reliable than small, retrospective analyses like this one.
Statistical noise in small samples can produce misleading associations, which is why researchers treat such findings as hypothesis-generating rather than conclusive. The study’s design — looking backward from people already diagnosed with cancer — cannot establish whether diet influenced disease development.
Researchers plan to explore whether pesticide residues, oral contraceptive leverage, or other environmental factors interact with biological susceptibility in young non-smokers to influence lung cancer development. No mechanism has been proven.
Should people stop eating fruits and vegetables because of this study?
No. Experts explicitly warn against reducing fruit and vegetable intake based on this preliminary, unpublished research, which contradicts extensive evidence showing these foods protect against many cancers and chronic diseases.
What explains the link between healthy eating and lung cancer in young non-smokers?
The researchers speculate that pesticide residues on conventionally grown produce may play a role, but they did not measure actual exposure and stress the finding is only an association requiring further study.
