Abstract LB151: Ultra-processed food intake and colorectal cancer risk in the US NIH-AARP cohort

Abstract Background and Rationale: Ultra-processed foods (UPF) account for more than 50% of calories consumed by US adults. Strong evidence links whole grain and calcium intake to decreased colorectal (CRC) risk and processed meat intake to increased CRC risk. UPF are major sources of all three dietary factors, and prospective studies of UPF intake and CRC risk have been inconsistent. Our aim was to estimate the prospective association between UPF intake and CRC risk and explore potential effect measure differences by overall diet quality. Methods: We analyzed data from 274, 269 men and 187, 413 women, aged 50 to 71, who participated in the NIH-AARP Diet and Health Study and were cancer-free at baseline in 1995-1996. Dietary intake was assessed using a validated food frequency questionnaire, and UPF intake (g/1000 kcal/day) was classified according to the Nova system and categorized as sex-specific quintiles. Cox proportional hazards models, adjusted for potential confounders and total energy using the nutrient density method, were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for CRC risk, overall and by anatomic location (i.e., proximal colon, distal colon, or rectum). HR for the joint effect of UPF intake (quintiles) and diet quality (quartiles), measured using the Healthy Eating Index-2015, were estimated. Results: With more than 20 years of follow-up, 6420 and 3661 first primary CRC cases were identified in men and women, respectively. Mean UPF intake was 392 and 398 g/1000 kcal/day, representing 43% and 42% of total daily calories, for men and women, respectively. Higher UPF intake was not associated with higher CRC risk in men (HRQ5vs.Q1=0.91; 95% CI, 0.84-0.99; P-trend=0.32) or women (HRQ5vs.Q1=0.93; 95% CI, 0.84-1.04; P-trend=0.58) overall or by anatomic location (all P-trend≥0.05). Lower diet quality (i.e., HEI Q1) was associated with higher CRC risk across all quintiles of UPF intake (HRHEI-Q1 & UPFQ1 vs. HEI-Q4 & UPFQ1=1.16; 95% CI, 1.02-1.32 and HRHEI-Q1 & UPFQ5 vs. HEI-Q4 & UPFQ1=1.16; 95% CI, 1.03-1.31; P-heterogeneity=0.11). Notably, 83% and 32% of whole grain and dietary calcium intake and 74.3% of processed meat intake came from UPF sources. Conclusions: In NIH-AARP, higher UPF intake was not associated with CRC risk. UPF include a heterogenous array of foods, which may have opposing effects on CRC etiology. Poor diet quality, potentially irrespective of degree of food processing, is associated with increased CRC risk. Citation Format: Leila Abar. Ultra-processed food intake and colorectal cancer risk in the US NIH-AARP cohort [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_2):Abstract nr LB151.