Prostate cancer & lifestyle

Nutrition Action Healthletter, Oct, 2005

Diet, exercise, and stress management may keep PSA levels from rising in patients with early, low-grade prostate cancer.

Dean Ornish of the University of California-San Francisco and colleagues studied 93 men who chose not to undergo any conventional treatment for early prostate cancer (their PSA levels were 4 to 10 and their Gleason scores were less than 7).

Half (the control group) were told to follow their doctor's advice. The other half (the lifestyle group) were told to follow a very-low-fat vegan diet (no meat, fish, poultry, eggs, or dairy) consisting largely of fruits, vegetables, whole grains, and beans. The diet was supplemented with soy (one serving a day of tofu and a fortified soy protein powdered beverage), plus daily doses of fish oil (3,000 milligrams), vitamin E (400 IU), selenium (200 micrograms), and vitamin C (2,000 mg).

In addition, the lifestyle group was told to do moderate aerobic exercise (walking 30 minutes six days a week) and yoga-like stress management, and to attend a support group (one hour a week).

After one year, the average PSA went from 6.23 to 5.98 in the lifestyle group and from 6.36 to 6.74 in the control group, a difference that was statistically significant but "relatively modest," according to the authors. However, six control patients--but no lifestyle patients--dropped out of the study because their PSAs rose or their cancers progressed.

What's more, blood samples from the lifestyle group inhibited the growth of prostate cells in test tubes more than blood from the control group. Researchers don't know if those results predict the spread of cancer in people. (The test-tube results are "provocative," say the authors.)

What to do: If you've decided not to undergo conventional treatment for early prostate cancer, you might consider a very-low-fat vegan diet, exercise, and stress management. But this study, while promising, didn't show clearly enough whether, or how much, that regimen can slow prostate cancer. Nor did it show which part of the program (diet, exercise, or yoga) or which part of the diet might have made a difference.

Journal of Urology 174:1065, 2005.