The study included 48 men who had surgery or radiation therapy to treat localized prostate cancer.
All of the men drank 8 ounces of pomegranate juice daily, and that slowed down the time it took for their PSA levels to double, as the researchers reported in 2006.
After that, the researchers -- who included Stanford University urologist Allan Pantuck, MD -- kept following the patients every three months. Fifteen of the patients stayed with the study for up to 64 months (a little more than five years), and it typically took four times longer for their PSA levels to double when they were drinking pomegranate juice, compared to their PSA doubling time at the study's start.
The results were presented at the American Urological Association's 104th annual scientific meeting in Chicago.
Five of the six researchers who conducted the study disclose ties to POM Wonderful, which makes the pomegranate juice used in the study.
In 2007, another team of researchers bought pomegranates, made their own pomegranate juice, and tested it against human prostate cancer cells grafted into mice. Those tumors grew slower than other tumors treated with a placebo solution.