OBJECTIVES: I. Determine the effects of 2 dietary regimens on levels of prostate-specific antigen (PSA) in patients with prostate cancer. II. Determine the compliance of these patients with the dietary regimen. III. Evaluate the effects of the dietary regimen on quality of life in these patients. IV. Evaluate the effects of the dietary regimen on PSA anxiety in these patients. V. Evaluate the effects of the dietary regimen on obesity, high blood pressure, and serum cholesterol in these patients.