Researchers from the University of California, Los Angeles report that extracts of the fruit were associated with a two-fold suppression in the expression of genes linked to prostate cancer.
“This study showed that pomegranate products and their polyphenols reduced tumour cell growth and induced apoptosis in both androgen-dependent and androgen-independent prostate cancer cells,” wrote the authors in the Journal of Nutritional Biochemistry
“These anti-proliferative effects were also consistent in hormone-treated cells. This implies the potential possibility that pomegranate and its polyphenols are used as novel dietary supplements with maximum potential for androgen-dependent and androgen-independent prostate chemoprevention.”
Pomegranate juice and extracts were supplied by POM Wonderful.
Pomegranate, a rich source of antioxidants, has been linked to improved heart health, but a growing body of science indicates the fruit protect against prostate cancer. Studies have also reported a role in joint health by slowing cartilage loss in arthritis.
It is these antioxidants, and particularly ellagitannin compounds like punicalagins and punicalins, which accounts for about half of the fruit's antioxidant ability, that are reportedly behind the proposed health benefits.
According to the researchers, early stage prostate tumours are dependent on testosterone levels circulating in the blood, but recurrent prostate tumours become unaffected by circulating testosterone levels. The cancer cells themselves can then increase testosterone synthesis, and this is linked to an over-expression of the so-called androgen receptor (AR).
Using androgen-dependent and androgen-independent prostate cancer cell lines, Mee Young Hong, Navindra Seeram, and David Heber from UCLA investigated if pomegranate extract and juice had an effect on the expression of genes for key androgen-synthesising enzymes and the androgen receptor.
They report that the polyphenols from pomegranate were capable of stopping the spread of both types of cancer, and that the compounds promoted apoptosis (programmed cell death) in the cells.
Building the science
The study follows similarly positive results from UCLA published in 2006 in the journal Clinical Cancer Research (Vol. 12, pp. 4018-4026). In that instance, 46 men were given eight ounces (227g) of pomegranate juice (Wonderful variety, equivalent to 570 mg of polyphenols) every day, and followed in three-month intervals.
The researchers found that the average doubling time increased from an average of 15 months to 54 months for the men drinking the pomegranate juice.
Over half a million men worldwide are diagnosed with prostate cancer every year, with over 200,000 deaths from the disease. The lowest incidence of the cancer is in Asia and the Far East, in particular India and China.
Source: The Journal of Nutritional BiochemistryDecember 2008, Volume 19, Issue 12, Pages 848-855“Pomegranate polyphenols down-regulate expression of androgen-synthesizing genes in human prostate cancer cells overexpressing the androgen receptor”Authors: M. Young Hong, N.P. Seeram, D. Heber