A new study has demonstrated that ellagitannin compounds derived from pomegranate fruit can reduce estrogen receptor positive (ER+) breast cancer proliferation by inhibiting aromatase activity. Estrogen stimulates the growth of ER+ tumors. Androgen is converted to estrogen in the body by the aromatase enzyme, thereby promoting such breast cancer. Pomegranate fruit, which is a rich source of ellagitannins, has attracted notice because of its reported anticancer and anti-atherosclerotic properties. Pomegranate ellagitannins hydrolyze upon consumption, releasing ellagic acid, which is then converted to various derivative compounds by microflora in the gut. In the study, 10 ellagitannin-derived compounds were tested. All were found to exhibit antiproliferative activity, and six were found to have anti-aromatase activity, the strongest of which was demonstrated by urolithin B. Further testing demonstrated that urolithin B significantly inhibited testosterone-induced MCF-7aro cell proliferation. MCF-7aro breast cancer cells are estrogen receptor positive/aromatase positive and demonstrate increased cell proliferation in the presence of testosterone. The authors conclude that pomegranate ellagitannin-derived compounds have potential for the prevention of estrogen-responsive breast cancers.
Other studies have also reported chemopreventive activities of pomegranates
Previous studies have also found that pomegranate-derived compounds inhibit aromatase in breast cancer cells. Studies have also found other anti-breast cancer activities of pomegranates:
- Punicic acid, a component of pomegranate seed oil, has been found to reduce the growth and proliferation of estrogen-negative (ER-) breast cancer cells
- Delphinidin, a major anthocyanin present in pomegranates and other pigmented fruits and vegetables, has been shown to possess potent antioxidant and antiproliferative properties in HER2 overexpressing breast cancer cells
- Pomegranate seeds contain a large fraction of conjugated linolenic acid, which has been shown to have chemopreventive effects against breast cancer
- Pomegranate seed oil and fermented pomegranate juice polyphenols have both been shown to inhibit angiogenesis in both ER+ and ER- breast cancer cells
- Pomegranate juice has been found to inhibit proliferation of ER- breast cancer cells in a dose- and time-dependent manner to a degree comparable to that of high-dose Cisplatin chemotherapy
- A pomegranate extract has been found to greatly inhibit tumor growth in Her2/neu transgenic mice
- Pomegranate juice has been found to have greater antiproliferative, apoptotic and antioxidant activities than individual pomegranate components, including punicalagin, ellagic acid, and pomegranate tannins, suggesting that compounds in the juice act synergistically compared to single purified active ingredients
- Pomegranate fermented juice polyphenols and pomegranate seed oil have both been shown to reduce the number of carcinogen-induced mammary tumors in mice.
Pomegranates would appear to be an ideal breast cancer chemopreventive agent were it not for the fact that pomegranates are a significant source of a wide variety of phytoestrogens. Several studies have found that pomegranate juice has estrogenic properties, increasing the uterine weight of ovariectomized rats.
Avoid pomegranate supplements and extracts
The safety and efficacy of consumption of large amounts of pomegranate juice, pomegranate seed oil and pomegranate extract needs to be confirmed in large scale clinical trials. Therefore, we conclude that breast cancer patients, survivors and those at high risk can enjoy pomegranates and pomegranate juice, but should avoid "enhanced" pomegranate juice, pomegranate seed oil and pomegranate extracts.