PURPOSE To identify dietary factors that are related to premature aging in adult survivors of childhood cancer, we examined the associations between plant food intakes and age-related deficit accumulation. METHODS A total of 3,322 childhood cancer survivors (age 18-65 years, mean = 31, standard deviation = 8.4) in the St Jude Lifetime Cohort had total fruit, total vegetables and subgroups, whole grains, refined grains, nuts/seeds, and nutrients intake assessed using a food frequency questionnaire. Premature aging at baseline was assessed by the deficit accumulation index (DAI) and categorized as low, medium, and high risk. Multinomial logistic regressions (reference: low risk) adjusting for confounders estimated odds ratios (ORs) and 95% CIs. Multivariable linear regression of a continuous intake against a continuous DAI was also performed. RESULTS Dark green vegetable (OR_{high v low} = 0.47 [95% CI, 0.28 to 0.78] per 1/2 cup/1,000 kcal increment) and nuts/seeds intakes (OR_{high v low} = 0.71 [95% CI, 0.47 to 1.08] per 1 oz/1,000 kcal increment; coefficient_linear = -0.0115, P = .02) were associated with a lower risk of premature aging. Conversely, refined grain intake was related to an increased risk of premature aging (OR_{high v low} = 1.33 [95% CI, 0.99 to 1.78], per 1 oz/1,000 kcal increment; coefficient_linear = 0.0093, P = .005). Fruit and whole grain intakes were not associated with premature aging risk. Among nutrients abundant in plant foods, dietary folate intake was associated with a lower risk of premature aging (OR_{high v low} = 0.89 [95% CI, 0.80 to 0.99] per 50 mcg/1,000 kcal increase). Beta-carotene, lutein/zeaxanthin, and vitamin E intakes from foods were also related to a modestly lower, but not statistically significant, risk of premature aging. CONCLUSION Specific plant foods are associated with lower risk of premature aging, providing targets for the interventions to promote healthy aging in childhood cancer survivors.