Large study finds no clear link between ultra-processed foods and colorectal cancer in older adults

Those findings do not show that particular foods caused or prevented cancer. They do suggest that collapsing everything from whole-wheat bread to processed meat into one category can obscure the dietary components that matter most. The authors said the results remain consistent with guidance to consume whole grains, fiber, dairy and calcium and to avoid processed meat for colorectal cancer prevention.

What the study cannot answer

The research was observational, so it cannot establish cause and effect. Diet was self-reported once at enrollment, which leaves room for measurement error and does not capture how eating habits or the food supply changed over more than two decades. Residual confounding is also possible.

The cohort was older and mostly white. The authors cautioned that the findings may not generalize to younger or more diverse populations. That makes the study a poor test of what may be driving rising colorectal cancer rates among adults under 50, the question highlighted in NBC News’ report.

Earlier prospective studies have produced mixed results, including associations that differed by sex and population. This new analysis narrows one part of the debate, but it does not settle whether specific ultra-processed foods, additives or dietary patterns affect colorectal cancer risk in other groups.