While most scientists and physicians have widely held the belief that all alcohol consumption increases the risk of breast cancer, a new study in the Journal of Women’s Health has found one alcoholic beverage that’s the exception to this rule: red wine. Glenn Braunstein, M.D., and his colleagues at Cedars-Sinai Medical Center in Los Angeles have shared results showing that the skins of red grapes contain certain chemicals called Aromatase Inhibitors (AIs), which can actually decrease the likelihood of a premenopausal woman developing breast cancer.The results, published online on December 7, 2011, may indicate good news to those women at-risk for breast cancer who still like to have a glass of wine with dinner — they will just need to choose the red over the white, which does not contain the AIs.The study compared the effects of drinking one 8-ounce glass of Cabernet Sauvignon versus Chardonnay each night with food for 21 days, and then switching so that the groups drank the reverse for another 21 days (the women were instructed to abstain from consuming either wine during their periods). Braunstein and his co-authors found “evidence that red wine, through the hormonal shift patterns, may not elevate breast cancer risk like other alcoholic beverages.”

The way that the AIs work is by preventing “the conversion of androgens to estrogen,” and they “occur naturally in grapes, grape juice, and red, but not white wine,” said the article. Other alcohols have been previously determined to raise estrogen levels in women, which is a key risk factor for breast cancer.

But these good results do come with a warning from Dr. Braunstein himself, who wrote in a Huffington Post article about the importance of taking your wine with a grain of salt, so to speak. He cautioned, “The choice to drink moderately will depend on who you are. A fit 25-year-old marathon runner with no family history or cardiac disease and no additional risk factors who doesn’t drink now probably won’t gain anything by joining a wine of the month club. Meanwhile, a man well into his AARP membership with little risk of cancer and some concerns about heart disease, may as well keep his nightly glass of wine with dinner if that’s his lifelong custom.”

The most recent statistics from the Center for Disease Control note that in the U.S. in 2007, over 200,000 women were diagnosed with breast cancer, with over 40,000 of those women died of the disease. “Except for skin cancer,” writes the CDC website, “breast cancer is the most common cancer among American women.”

The Journal of Women’s Health study’s co-authors include Chrisandra Shufelt, M.D., M.S.; C. Noel Vairey Merz, M.D.; YuChing Yang, Ph.D.; Joan Kirschner, M.S.N., N.P., Donna Polk, M.D., Frank Stanczyk, Ph.D., and the late Maura Paul-Labrador, M.P.H.