Breast cancer: estrogen suppression by compounds found in red wine and grape seeds.

Eng ET, Ye J, Williams D, Phung S, Moore RE, Young MK, Gruntmanis U, Braunstein G, Chen S. 2003. Suppression of estrogen biosynthesis by procyanidin dimers in red wine and grape seeds. Cancer Res 63:8516-8522.

Many epidemiologic studies have shown that eating a diet high in fruits and vegetables is associated with reduced cancer incidence, with multiple studies focusing on wine and grape consumption. In this study, NIH grantees including first author Elizabeth T. Eng of the Beckman Research Institute of the City of Hope have identified a class of compounds called procyanidin B dimers as the most abundant aromatase inhibitors in red wine, suggesting that these compounds may be responsible for red wine's observed chemo-preventive effect against breast cancer.

Other studies have shown that the production of estrogens in breast cancer tissue plays a major role in tumor progression--approximately 75% of postmenopausal patients have estrogen-dependent cancers. Aromatase, a P450 enzyme, synthesizes estrogen by converting androgen substrates into estrogens. Aromatase is highly expressed in breast cancer tissue, and suppression of in situ estrogen formation by aromatase inhibitors is considered a viable means of preventing and treating breast cancer in postmenopausal women. Previous research from this and other laboratories has shown that extracts from red wine inhibit aromatase activity.

High concentrations of procyanidin B dimers had already been found in grape seeds. Eng and colleagues found, through laboratory analyses, that the most potent procyanidin B dimer competed with the androgen substrate for binding with aromatase. Additional in vitro studies showed that the dimers were able to reduce androgen-dependent tumor growth, indicating that these chemicals reduce the production of estrogens from the androgen substrates.

This study, and earlier work by the same team, demonstrates that procyanidin B dimers in red wine could be used as chemopreventive agents against breast cancer by inhibiting the conversion of androgens to estrogens in breast tissue. The researchers estimate that a single four-ounce glass of red wine daily could provide enough procyanidin B dimers to inhibit aromatase activity in the average postmenopausal woman.