If you are confused about whether alcohol increases or decreases your risk for breast cancer, you are not alone. Many studies have linked daily alcohol consumption to an increase in the incidence of various cancers. On the other hand, resveratrol, which is found in red wine, red grapes and many other berries and plants, is associated with a decrease in the risk for breast cancer. Now, a new study has found that red wine, but not white wine, contains an inhibitor of an enzyme that helps to reduce estrogen in breast tissue and therefore helps to stop the growth of estrogen-dependent breast cancers.
How estrogen is made
It takes many steps to synthesize estrogen from cholesterol in the body. The last step is the conversion of male hormones (androgens) such as testosterone to estrogen. This last step requires an enzyme, called aromatase. Estrogen is made primarily in the ovaries, but is also synthesized in the adrenals, fat tissue and breast tissue.
Aromatase and breast cancer
Inhibition of aromatase has become an important treatment in the fight against breast cancer. Aromatase is present in breast tissue and produces local estrogen, which then fuels the growth of estrogen receptor-positive breast cancers. Estrogen receptor-positive breast cancers make up the majority of breast cancers (about 75 percent). Inhibitors of aromatase to prevent the production of estrogens are very effective in postmenopausal women. But these inhibitors are less effective in reducing the large amounts of estrogens produced by the ovaries in premenopausal women.
Red wine vs. white wine
If you drink alcohol, it can increase the amount of estrogen in your body and therefore increase your breast cancer risk, according to some studies. Red wine may be an exception. Not just does it contain the antioxidant resveratrol, but red wine, red grape juice, and the skins and seeds of red grapes also contain an inhibitor of aromatase, according to the new research. Premenopausal women, who drank eight ounces of red wine daily for a month, had lower estrogen and higher testosterone levels. The same amount of white wine did not have such effects. In the study, women who drank red wine for a month were then switched to white wine, and women who had been on white wine were switched to red wine for another month. Blood samples were taken at specified times to monitor hormone levels and other related substances. Only red wine caused the changes associated with aromatase inhibition.
This new study suggests that if you like to drink alcohol, you may want to switch to red wine. Eating red grapes or drinking red grape juice may also be helpful. Also, the new research suggests that an aromatase inhibitor as found in red wine may not just benefit postmenopausal women, but also premenopausal women, since the study was done in premenopausal women. The authors of the study write: "These data suggest that red wine is a nutritional AI [aromatase inhibitor] and may explain the observation that red wine does not appear to increase breast cancer risk" (Shufelt, C. et al.).
Shufelt, C. et al. Red Versus White Wine as a Nutritional Aromatase Inhibitor in Premenopausal Women. Journal of Women's Health (2011) doi: 10.1089/jwh.2011.3001