A daily glass of pomegranate juice showed potential for slowing the growth of prostate cancer in a small study but more evidence is needed before doctors recommend it, U.S. scientists said on Saturday.

A study funded by a juice maker found men who drank the beverage had a longer time until doubling of their blood levels of PSA — a protein that indicates the presence of prostate cancer. Patients with short doubling times are more likely to die from the cancer.

In the study, the time until PSA doubling after treatment extended to 54 months on average when the men started drinking eight ounces of pomegranate juice a day. Before drinking the juice, PSA doubled in an average of 15 months.
"That’s a very big difference. … It’s an indicator of how quickly the cancer is growing," said Dr. Allan Pantuck, a urologist at UCLA Jonsson Cancer Center and the study’s lead author.

Each of the 50 men who took part had radiation, surgery or other treatment for prostate cancer before enrolling in the study. No major side effects were reported from drinking the juice.

"It’s too early to tell people with prostate cancer they should drink pomegranate juice" because the evidence is preliminary, Pantuck said in an interview.

A larger study is under way to try to confirm the findings, with results expected in two years, he said.

While he does not expect pomegranate juice to cure prostate cancer, Pantuck said it could delay or prevent the need for other therapies with harsh side effects including hot flashes, fatigue, depression and impotence.

Pomegranate juice "is a very non-toxic treatment that, if it really did have that effect on doubling time, could prevent many people from going on to metastatic disease and hopefully from dying of prostate cancer," he said.

The research team said substances known as polyphenols or other ingredients in the fruit juice may be able to fight prostate cancer, but exactly how is unclear. The benefits probably come from a combination of ingredients, they said.

The findings were published in the peer-reviewed journal Clinical Cancer Research and funded by a trust established by the owners of Pom Wonderful, a brand of pomegranate juice. Pom Wonderful supplied the juice used in the study.