The association between the comprehensive dietary antioxidant index and the risk of gastrointestinal cancer: A cross-sectional study based on NHANES

Background Gastrointestinal cancer accounts for approximately one-third of global cancer incidence and mortality. The early screening rates remain low, which leads to a poor prognosis. Identifying modifiable risk factors is therefore a pressing need. Oxidative stress plays a pivotal role in gastrointestinal carcinogenesis. Dietary antioxidants may mitigate this process by neutralizing reactive oxygen species. However, studies focusing on single nutrients have limitations due to their inability to capture the synergistic effects of multiple dietary components. The Composite Dietary Antioxidant Index (CDAI) is a quantitative measure that evaluates the combined impact of various dietary antioxidants. The relationship between CDAI and gastrointestinal cancer risk warrants further investigation. Objective To examine the association between CDAI and the risk of gastrointestinal cancer. Method Cross-sectional data from NHANES 2005–2023 were utilized to calculate CDAI scores. Logistic regression models, restricted cubic splines, and subgroup analyses were employed to comprehensively assess the relationship between CDAI and gastrointestinal cancer risk. Result Among the 21,762 participants included in the study, the high CDAI group consisted predominantly of males, individuals with high socioeconomic status (non-Hispanic whites, high income), and those who engaged in healthy behaviors (low smoking rates, low body mass index). Multivariate analysis revealed that CDAI scores were significantly lower among females, current smokers, and obese individuals, while higher scores were observed in the high-income group. The association analysis demonstrated that for every 1-unit increase in CDAI, the risk of gastrointestinal cancer decreased by 4.55% (OR = 0.9545). This protective effect was more pronounced among individuals with obesity, females, and non-Hispanic whites. No significant association was identified between CDAI and non-gastrointestinal cancers. Conclusion Higher CDAI scores are associated with a diminished risk of gastrointestinal cancer, particularly among females, individuals with obesity, and non-Hispanic whites. These findings highlight the potential preventive role of dietary antioxidants in gastrointestinal tumor development.