OBJECTIVES: Considerable evidence has shown that diet can affect both the incidence and the progression of prostate cancer. The objective of this study was to determine whether men in this situation could make a change to a diet emphasizing plant-based foods and fish and to examine the effect on quality of life (QOL) and prostate-specific antigen (PSA) velocity.

METHODS: A total of 36 men and their partners were randomly assigned to attend a series of 11 dietary and cooking classes that also integrated mindfulness practice as a support in making the change or a wait-list control group. Assessments were made of dietary intake, QOL, and PSA at baseline, after intervention (11 weeks), and 3 months after intervention.

RESULTS: The intervention group showed significant reductions in the consumption of saturated fat and increased consumption of vegetable proteins with accompanying reductions in animal proteins, including dairy products. They also showed increased QOL. Although no significant change was found in the rate of PSA increase between the two groups, the mean PSA doubling time for the intervention group was substantially longer at the 3-month follow-up visit than that of the controls.

CONCLUSIONS: Men with a increasing PSA level after primary treatment were able to make a change to a prostate-healthy diet, accompanied by increases in QOL. No significant difference was found in the log PSA slope between the two groups; however, the PSA doubling time increased substantially in the intervention group compared with that in the controls. Future trials should examine the effect of the prostate-healthy diet with a larger sample of men for a longer period.