Low-fat, vegetarian diet slows PSA doubling time

NEW YORK (Reuters Health) - A diet low in saturated fat, high in vegetable protein and low in animal protein, including dairy products, is associated with a “substantial” increase in prostate-specific antigen (PSA) doubling time and an increase in quality of life, according to results of a pilot study.

PSA is used as a biological marker for prostate cancer; the higher this number gets, the greater is the man’s risk of prostate cancer or prostatitis (inflammation of the prostate). The PSA “doubling time” is the time it takes for PSA levels to increase by 100 percent.

The study subjects included 36 men with biopsy-confirmed prostate cancer who had received primary treatment for more than 6 months previously and who had increasing PSA levels.

Dr. James Carmody and colleagues at the University of Massachusetts Medical School in Worcester randomly assigned the subjects and their partners to attend 11 dietary and cooking classes and mindfulness practice to support the change in diet or to a control group.

Assessments of dietary compliance, quality of life and PSA levels were made at the beginning of the study, after the 11-week intervention, and again 3 months after the intervention was assessed. The findings are published in the journal Urology.

The intervention group consumed significantly less saturated fat, more vegetable protein and less animal protein, including dairy products, than did the controls. They also reported more indicators of increased quality of life compared with the controls.

“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,” Dr. Carmody and colleagues report.

“Future clinical trials should examine the effect of a similar diet on clinical disease markers of disease progression with a larger sample of men followed for a substantially longer period.”

SOURCE: Urology, December 2008.