The study – published in the Journal of Women's Health – investigated the possibility that red wine consumption was associated with hormonal changes linked to breast cancer reduction by comparing levels of important hormones in people consuming a moderate amount of red and white wine daily.
The researchers found that red wine consumption was associated with hormonal changes – such as increasing free testosterone and lowering levels of female sex hormones.
The findings suggest that red wine “is a nutritional aromatase inhibitor and may explain the observation that red wine does not appear to increase breast cancer risk,” say the study authors – led by Dr Glenn Braunstein of the Cedars-Sinai Research Institute, USA.
“Our results in a controlled setting provide a potential mechanistic pathway whereby red wine may serve as a nutritional AI. They provide further evidence that red wine, through the hormonal shift patterns, may not elevate breast cancer risk like other alcoholic beverages,” said Braunstein and his team.
Braunstein explained that "there are chemicals in red grape skin and red grape seeds that are not found in white grapes that may decrease breast cancer risk.”
The team added that their findings challenge the widely-held belief that all types of alcohol consumption heighten the risk of developing breast cancer.
Previous research has consistently reported that alcohol consumption – including wine – increases the risk of breast cancer. However, there have also been several studies demonstrating the potentially healthy benefits of certain compounds found in red wine, and as such, whether red wine raises or lowers the risk remains controversial.
Braunstein and his colleagues noted that aromatase inhibitors (AIs) prevent the conversion of androstenedione and testosterone into oestrogen, leading to increases in blood testosterone and decreases in oestradiol, oestrone, and sex hormone binding globulin (SHBG) levels. This pathway is known to play an important role in the management and treatment of oestrogen receptor–positive breast cancer in postmenopausal women – however its role in premenopausal women is under investigation.
The research team noted that several potentially chemoprotective chemicals have been identified in red wine, including isoflavone phytoestrogens, flavones, and procyanidin B dimers.
“All of these chemicals have AI activity on the cytochrome P450 aromatase enzyme in both in vitro and in vivo studies,” said Braunstein and his team.
Other chemicals in wine, includng resveratrol, rutin, and quercetin, are suggested to inhibit aromatase but have not been clearly established, they said.
In a randomized cross-over design, 36 premenopausal women were assigned to either red wine (Cabernet Sauvignon) or white wine (Chardonnay) daily for almost a month, before being switched to the other type of wine. Blood was collected twice each month to measure hormone levels.
Braunstein and his co-workers revealed that the change in hormone patterns found from red wine consumption – including higher free testosterone and lower SHBG levels – suggest that it could block the growth of cancer cells, as has been shown in test tube studies.
However he noted that large-scale studies still are needed to evaluate the safety and effectiveness of red wine to assess whether it specifically alters breast cancer risk.
Source: Journal of Women's Health
Published online ahead of print, doi: 10.1089/jwh.2011.3001
“Red Versus White Wine as a Nutritional Aromatase Inhibitor in Premenopausal Women”
Authors: C. Shufelt, C.N.B. Merz, Y.C. Yang, J. Kirschner, D. Polk, et al