As with heart disease, obesity, and diabetes, diet and exercise can help reduce the risk of acquiring prostate cancer, a glandular disease that affects 1 in 6 men. Recently, researchers found evidence that these lifestyle changes not only help prevent prostate cancer but might also help stop or reverse the cancer in men already diagnosed with the disease.

For one year, researchers from the University of California–San Francisco and Memorial Sloan-Kettering Cancer Center put 44 prostate cancer patients on a strict lifestyle adjustment program that included a vegan diet (no animal products); vitamins; an exercise program of moderate aerobics, yoga, and meditation; and weekly meetings with a support group. An additional 49 patients served as a control group and continued with their meat-eating, unenlightened, couch-potato lifestyle.

Researchers found that the men who undertook these drastic lifestyle changes fared better than those who didn't. At the start of the study, none of the 93 men in the experiment received any conventional prostate cancer treatment. But by the end of the trial, six patients in the control group needed conventional treatment such as radiation therapy, surgery, or hormone therapy. No patients in the diet and exercise group needed these treatments.

Blood chemistry levels also looked better for the diet and exercise group. Researchers consider elevated PSA (prostate-specific antigens) blood levels a sign of prostate cancer. While PSA levels increased by about 6 percent in the control group, PSA levels decreased by 4 percent in men with changed lifestyles.

Finally, researchers tested each man's serum, the liquid part of the blood without red and white blood cells, on prostate tumor cells grown in the lab. Serum from those men with a healthy diet and exercise program inhibited tumor cell growth by 70 percent, while the control group's serum inhibited cell growth by only 9 percent.

The paper's lead author, Dean Ornish, a researcher with the University of California–San Francisco, says these results don't mean that people should forgo conventional cancer treatments, adding that the link between lifestyle and prostate cancer progression needs more research. Ornish is the founder and president of the Preventative Medicine Research Institute, a nonprofit organization that promotes comprehensive lifestyle change to treat coronary artery disease and, now, early stage prostate cancer.

Duke University urology professor Judd W. Moul, who was not associated with this study, agrees that more research is needed.

"I really want to be an optimist and a cheerleader for his work because it's important," says Moul. "But, it's possible that the diet affected the biomarker, PSA, but didn't affect the underlying disease."

Nevertheless, eating good food and exercising will almost always make you healthier. Ornish's results are similar to a diet and exercise study he conducted on the progression of heart disease.

"People think that it has to be a new drug or laser for a new treatment," says Ornish. "In our studies, we used these very high-tech measures to prove the power of these very ancient low-tech and low-cost interventions."