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.