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Background

Ultra-processed foods (UPF) account for >50% of calories consumed by US adults. Strong evidence links whole grain, fiber, calcium, and dairy intake to lower and processed meat intake to higher colorectal (CRC) risk. UPF, include some whole grain and dairy products and most processed meats. Studies of UPF intake and CRC risk are inconsistent.

Objective

To estimate the association between UPF intake and CRC risk as well as to evaluate the joint effect of UPF intake and diet quality with CRC risk and to estimate associations of select food groups and nutrients with CRC risk by UPF and non-UPF source .

Methods

US adults, aged 50-71, who participated in the NIH-AARP Diet and Health Study self-reported dietary intake using a validated food frequency questionnaire (FFQ). We assigned disaggregated FFQ items to Nova classification and categorized UPF intake (g/1000 kcal/day) into sex-specific quintiles. We used multivariable-adjusted Cox proportional hazards regression models to estimate hazard ratios (HR) and 95% confidence intervals (CI) for CRC.

Results

Over 20 years of follow-up, 10,075 colorectal adenocarcinoma cases were diagnosed among 461,682 participants who were cancer-free at baseline. Median UPF intake was 293 g/1000 kcal/day or 43% of daily energy intake. UPF intake was not associated with incident CRC (HR _Q5vs.Q1 =0.97; 95% CI, 0.91-1.03; P _trend =.55) overall or by anatomic location (all P _trend >.05). Whole grain, dairy, and calcium intake were inversely but meat intake was positively associated with CRC risk regardless of processing level.

Conclusions

Total UPF intake was not associated with incident CRC in this cohort of older, US adults. This may be explained, in part, by opposing effects of some UPF on CRC etiology. Our findings support current dietary guidance to consume whole grains, fiber, dairy, and calcium and avoid processed meat for CRC prevention.