This study explores the relationship between the composite dietary antioxidant index (CDAI) and biological aging in the US population. Using data from the National Health and Nutrition Examination Surveys (NHANES), researchers found that higher CDAI scores were associated with delayed biological aging. CDAI is a measure of dietary antioxidant intake, including manganese, selenium, zinc, and vitamins A, C, and E. Biological age was assessed using the PhenoAge algorithm, which incorporates clinical biomarkers and blood cell parameters. The study found a significant inverse relationship between CDAI and PhenoAge, with each standard deviation increase in CDAI score linked to a 0.18-year decrease in biological age. This relationship was consistent across various subgroups, including age, gender, physical activity, smoking status, and BMI. The findings suggest that a higher CDAI score is linked to a reduced risk of age-related diseases. The study also highlights the importance of dietary antioxidants in mitigating oxidative stress and slowing down the aging process. While the study has limitations, including a cross-sectional design and potential selection bias, it provides evidence that dietary antioxidants may play a key role in promoting healthy aging. The results have implications for public health initiatives aimed at improving dietary habits to delay biological aging.This study explores the relationship between the composite dietary antioxidant index (CDAI) and biological aging in the US population. Using data from the National Health and Nutrition Examination Surveys (NHANES), researchers found that higher CDAI scores were associated with delayed biological aging. CDAI is a measure of dietary antioxidant intake, including manganese, selenium, zinc, and vitamins A, C, and E. Biological age was assessed using the PhenoAge algorithm, which incorporates clinical biomarkers and blood cell parameters. The study found a significant inverse relationship between CDAI and PhenoAge, with each standard deviation increase in CDAI score linked to a 0.18-year decrease in biological age. This relationship was consistent across various subgroups, including age, gender, physical activity, smoking status, and BMI. The findings suggest that a higher CDAI score is linked to a reduced risk of age-related diseases. The study also highlights the importance of dietary antioxidants in mitigating oxidative stress and slowing down the aging process. While the study has limitations, including a cross-sectional design and potential selection bias, it provides evidence that dietary antioxidants may play a key role in promoting healthy aging. The results have implications for public health initiatives aimed at improving dietary habits to delay biological aging.