The effect of adherence to the World Cancer Research Fund (WCRF) lifestyle recommendations on cancer aggressiveness is unknown. We examined associations between adherence to recommendations and risk of highly aggressive prostate cancer in research subjects enrolled in the North Carolina-Louisiana Prostate Cancer Project (PCaP). We examined associations between adherence to WCRF recommendations and risk of highly aggressive prostate cancer among 2212 newly diagnosed African Americans (AA) or Caucasian Americans (CA) aged 40-70 years in PCaP. Prostate cancer aggressiveness was based on Gleason scores, serum prostate-specific antigens, and TNM stage. Adherence to WCRF recommendations was based on point scores and odds ratios estimated. Results showed that adherence to recommendations was significantly and negatively associated with risk of a highly aggressive prostate cancer. Each additional point in the total adherence score corresponded to a 13% risk reduction. Total adherence score <4 predicted increased risk in both AA (OR = 1.36; 95% CI = 1.01-1.85) and CA (OR = 1.41; 95% CI = 1.01-1.98). Consumption of <500 g red meat per week or ≤125 total kcal/100 g solid food per day is a statistically significant protective factor in the overall cohort. Recommendations aimed at preventing all cancers also may reduce risk of highly aggressive prostate cancer.