Men who consumed a larger share of their daily calories from ultraprocessed foods were more likely to report having prostate cancer in a new analysis of U.S. health and nutrition data.
But the study, published in The American Journal of Medicine, comes with an important limitation: Researchers measured men's recent diets and prostate cancer history at roughly the same point in time. That means the findings show an association, not that higher ultraprocessed food intake came first or contributed to the development of cancer.
Researchers analyzed data from 17,024 men ages 18 and older who participated in the National Health and Nutrition Examination Survey, or NHANES, between 2003 and 2023.
Participants completed two 24-hour dietary recalls describing what they had recently eaten. Researchers then classified foods using the NOVA system, which groups foods according to how extensively they are processed.
Ultraprocessed foods can include products such as soft drinks, packaged snacks, some breakfast cereals, processed meats and ready-to-eat meals. But the category is broad and can also include foods with very different nutritional profiles, making it difficult to determine whether processing itself, specific nutrients or additives, or broader dietary patterns explain associations with health.
Researchers calculated what percentage of each participant's calories came from ultraprocessed foods and divided the men into four groups. Intake ranged from less than about 20% of calories from ultraprocessed foods in the lowest group to more than 44% in the highest.
Compared with men consuming the least, those in several of the higher-intake groups were more likely to report a history of prostate cancer.
After researchers accounted for age, race and ethnicity, smoking and poverty status, the increases remained statistically significant in several comparisons, ranging from about 24% to 31%.
The highest-intake group by itself had an estimated 34% higher likelihood of prostate cancer compared with the lowest group, but that result did not reach statistical significance.
“Among adult men in this nationally representative U.S. population, those who consumed higher amounts of UPFs had significantly higher risks of the subsequent development of prostate cancer,” said senior author Charles H. Hennekens, M.D., a professor at Florida Atlantic University.
The study design, however, cannot establish that prostate cancer developed after the diet researchers measured.
NHANES provides a snapshot of participants' health and eating habits rather than following cancer-free men over many years to see who eventually develops prostate cancer. A man who had already been diagnosed with prostate cancer, for example, may have changed what he ate before participating in the survey.
Two days of dietary recall also may not represent what someone typically ate over the many years during which cancer can develop.
Other differences among people who eat more or fewer ultraprocessed foods could also help explain the association. Researchers adjusted for several factors, including age, smoking and poverty, but observational studies cannot account perfectly for every difference in health, lifestyle or diet.
The new findings also enter a research area where the evidence remains mixed.
A 2024 review and meta-analysis combined results from six previous studies examining ultraprocessed food intake and prostate cancer. Overall, researchers found no statistically significant association between consuming more ultraprocessed foods and prostate cancer risk.
More broadly, studies have linked higher ultraprocessed food intake with a number of health outcomes, including obesity, type 2 diabetes and cardiovascular disease. Some research has also found associations with certain cancers.
But scientists are still working to determine what those findings mean.
The NOVA definition groups foods by processing rather than nutritional quality alone. Some ultraprocessed foods are high in calories, added sugars, sodium or saturated fat, while others may provide fiber, protein or other nutrients. People who consume more ultraprocessed foods may also differ in overall diet quality, physical activity, body weight, income and other factors related to health.
Researchers have proposed several possible explanations for links between diets high in ultraprocessed foods and cancer, including excess calorie intake, weight gain, inflammation and other metabolic changes. But those mechanisms were not tested in this study.
The findings therefore cannot show that industrial processing itself raises prostate cancer risk or identify particular ultraprocessed foods as responsible.
World Cancer Research Fund has similarly cautioned that while studies increasingly report associations between diets high in ultraprocessed foods and cancer, the evidence is not yet strong enough to say that ultraprocessed foods directly cause cancer.
The new study adds another observation to that evolving evidence base, but stronger research would be needed to determine whether the association holds up over time. Prospective studies that measure men's diets before a prostate cancer diagnosis, ideally with repeated dietary assessments over many years, could provide clearer answers.
The authors reported no funding for the study. They declared no conflicts of interest. Senior author Charles H. Hennekens also disclosed several professional and financial relationships, including serving in independent advisory roles for data monitoring committees involving Amgen, serving as a special government employee for the U.S. Food and Drug Administration, contributing to UpToDate, receiving textbook royalties and having an investment management relationship with the West-Bacon Group.