Association of the Composite Dietary Antioxidant Index with All-Cause, Cancer, and Cardiovascular Mortality: A...

Oxidative stress is a major contributor to chronic diseases such as cardiovascular disease (CVD) and cancer, and antioxidants may play a protective role. However, the link between overall dietary antioxidant intake, measured using the Composite Dietary Antioxidant Index (CDAI), and long-term health outcomes remains unclear. This prospective cohort study investigated the association between CDAI and cause-specific mortality, including CVD and cancer, as well as all-cause mortality and CVD incidence, using data from 6484 adults (mean age: 48.38 years, 39.98% male) in the Mashhad Stroke and Heart Atherosclerosis Disorder (MASHAD) cohort. Dietary intake was evaluated using a validated food frequency questionnaire, and CDAI was calculated from six dietary antioxidants. Participants were followed for 10 years. Kaplan-Meier survival analysis showed that individuals in the third and fourth quartiles of CDAI had significantly lower cancer mortality (p = 0.011) and cardiovascular mortality (p = 0.021). Multivariable Cox regression revealed a significant inverse association between CDAI and cardiovascular mortality in the second (OR = 0.531; 95% CI: 0.391-0.884) and third (OR = 0.535; 95% CI: 0.321-0.892) quartiles, but not in the fourth (OR = 0.847; 95% CI: 0.537-1.337). Higher CDAI was also linked to lower cancer mortality in crude (OR = 0.424; 95% CI: 0.224-0.802), first (OR = 0.384; 95% CI: 0.198-0.747), and second (OR = 0.398; 95% CI: 0.202-0.785) models, though this association weakened after full adjustment (OR = 0.469; 95% CI: 0.165-1.331). No significant link was found between the highest CDAI quartile and all-cause mortality (p > 0.05). Overall, these findings suggest that moderate antioxidant intake may offer protective effects, particularly for cardiovascular outcomes.