US researchers found that pomegranates contain six natural compounds that may prevent the growth of hormone-dependent breast cancer by blocking the enzyme aromatase, which changes androgen to estrogen. However, experts caution this does not mean people should expect the same results from eating pomegranates, because this was an “in vitro” (test tube) study and results on the lab bench don’t always translate to animals and humans.
The study, which was published in the 1 January issue of Cancer Prevention Research, is the work of Dr Shiuan Chen, director of the Division of Tumor Cell Biology at the Beckman Research Institute of the City of Hope, Duarte, California and colleagues also from City of Hope and the Center for Human Nutrition at the David Geffen School of Medicine, University of California Los Angeles.
For the study, the researchers screened ten compounds in a group known as ellagitannins.
Chen and his team found that the compound with the strongest impact was urolithin B (UB), which appeared to inhibit multiple estrogen-producing mechanisms that fuel the growth of breast cancer.
They also found that UB prevented estrogen-responsive breast cancer cells from multiplying.
Chen told the press that:
“By suppressing the production of estrogen, urolithin B and other phytochemicals found in pomegranates can prevent hormone-responsive breast cancer tumors from growing.”
The other phytochemicals they found were urolithin A (UA), methylated UA, acetylated UB, methylated UB and UB sulfate: these also inhibited aromatase activity but to a lesser extent.
Chen said the results of the study suggest that:
“Pomegranate intake may be a viable strategy for preventing breast cancer.”
According to a report by Cancer Research UK, Chen said he and his team were surprised by the findings, explaining that they had previously found other fruits, such as grapes, were also able to inhibit aromatase, “But phytochemicals in pomegranates and in grapes are different”, he said.
Experts are cautioning that further studies are needed before we can be sure that UB is effective against hormone-dependent breast cancer in humans: women should not start consuming lots of pomegranates on the strength of this study.
This was an in vitro (test tube) study, and sometimes such findings don’t translate to animal and human studies: for instance it might turn out that these substances aren’t well absorbed in the body by just eating pomegranates.
Dr Laura Bell, science information officer at Cancer Research UK, told the press that:
“It’s too big a leap to conclude from this early-stage research that eating pomegranates could help prevent hormone-dependent breast cancer as the study was done using large amounts of purified chemicals on cells grown in the lab.”
“In terms of cancer prevention, most foods contain many natural chemicals and we need to understand the combined effect of these when processed in the body to guess what influence, if any, a specific food may have on your chance of developing cancer,” she explained, adding that numerous large studies have shown that:
“By eating a healthy balanced diet high in fibre, fruit and vegetables and low in red and processed meat, saturated fat and salt, you can help to reduce your risk of several different types of cancer.”
Breast cancer drugs like anastrozole (Arimidex from AstraZeneca) are also designed to block the action of aromatase.
A team of scientists from the UK reported that turmeric, broccoli, green tea and pomegranate help prevent and halt prostate cancer, the most common cancer among adult males in the USA and UK.
Written by: Catharine Paddock, PhD