Analysis of 6,085 men with prostate cancer over three decades reveals that adherence to the Alternative Healthy Eating Index (AHEI) reduced all-cause mortality by 25%, while Mediterranean diet adherence decreased it by 20%. The study tracked participants for 71,760 person-years, documenting 3,710 deaths including 592 from prostate cancer and 971 from cardiovascular disease. This represents one of the largest and longest-running investigations into post-diagnosis dietary interventions for cancer survivors. The timing of dietary change proves crucial—men who improved their eating patterns after diagnosis experienced the greatest survival benefits, particularly those with less aggressive tumors. While the study found no direct impact on prostate cancer-specific mortality, the substantial reduction in cardiovascular deaths suggests these dietary patterns address the leading actual cause of death in this population. The findings challenge the traditional medical approach of focusing solely on cancer treatment while neglecting lifestyle factors. For the estimated 3.3 million American men living with prostate cancer, these results offer actionable evidence that dietary modification can meaningfully extend lifespan, making nutrition counseling an essential component of survivorship care rather than an optional add-on.