In the United States, breast cancer is the leading form of cancer for women. Studies have found that increased alcohol consumption leads to an increased risk of breast cancer, though it is controversial whether or not red wine, a beverage that is known for its wide range of health benefits, raises this risk as well.
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Currently, aromatase inhibitors (AIs) are used in the management and treatment of estrogen receptor-positive breast cancer, though most of the research has been done on postmenopausal women, and much less is known about the role of AI in premenopausal women. Mechanistically, AIs work to prevent the conversion of androstenedione and testosterone into estrogen, which lead to increased levels of testosterone and decreased levels of estradiol, estrone, and sex hormone globulin in the blood.
AIs have been found to be naturally occurring in grapes and red wine, but not in white wine. It can be assumed that these AIs are located in the skins and seeds of the grapes, since they are only found in red wines where skins are in contact with the juice at some point during processing, as opposed to white wines where there is no skin contact with the juice. Specifically, AIs that have been identified in red wine include isoflavone phytoestrogens, flavones, and procyanidin B dimmers. Other polyphenols, such as the well-known resveratrol and quercetin, have not been linked to AI activity, even in those wines containing higher levels of the compounds.
In a short study published last year (which you may or may not have already heard about), the authors aimed to test whether red wine versus white wine is beneficial in regards to AI activity in premenopausal women.
Methods
Eligible participants were premenopausal women with regular ovulatory cycles for the past 12 months. Inclusion criteria for the study were: a body mass index between 18.5 and 30, normal serum liver function, and a regular unrestricted diet. Exclusion criteria for the study were: irregular menstrual cycles or vasomotor symptoms within the last 12 months, pregnancy, breastfeeding, hormone therapy (including oral contraceptives) within the last 3 months, history of alcohol abuse, history of estrogen-dependent neoplasia, any chronic health conditions, and women aged younger than 21 years old. Participants agreed to use nonhormonal contraception for the duration of the study.
The study was a randomized cross-over design where participants were assigned either a red or a white wine in the first cycle, and the opposite in the second cycle. The red wine studied was Cabernet Sauvignon (BV Coastal, 2003) and the white wine studied Chardonnay (BV Coastal, 2003). Participants were asked not to consume any other alcoholic beverages or grape products throughout the study.
Participants were instructed to consume 8 ounces of the assigned wine in the evening with food from day 1 to day 21 and to not drive or operate heavy machinery for at least 3 hours after wine consumption.
The duration of each treatment (red and white wine) was one menstrual cycle. During the baseline menstrual cycle, participants did not consume any alcohol or grape products. Serum was collected from participants at early follicular (days 5-8) and mid-luteal (days 17-21) phases during baseline and the two wine treatment cycles. Serum hormone levels of the following were measured during these collection times: estrone, estradiol, androstenedione, testosterone, sex hormone binding globulin, luteinizing hormone, and follicle stimulating hormone. Between the two treatments, a wash-out period occurred where participants abstained from all alcohol and grape product consumption, which occurred after the mid-luteal serum collection day and day 0 of the next menstrual cycle.
Results
- 36 participants were enrolled and completed the study.
- There were no statistical differences according to treatment order assignment (either red wine first or white wine first) for baseline hormone characteristics or menstrual cycle length.
- Red wine consumption was associated with significantly higher testosterone levels and lower SHBG levels than white wine consumption.
- Overall estradiol levels trended toward being lower with red wine versus white wine, though it was not statistically significant.
- Luteinizing hormone levels were significantly higher after consuming red wine versus white wine.
- Follicle stimulating hormone levels trended toward being higher after red wine consumption than white wine consumption, though this was not statistically significant.
Conclusions
According to the authors, this study is the first of its kind to clinically test the hypothesis that red wine is a nutritional aromatase inhibitor in premenopausal women. The results showed that red wine consumption was associated with higher free testosterone levels and lower sex hormone binding globulin than with white wine consumption. Non-significance with estrogen levels, according to the authors, could have been due to large variability and error across samples, which may be remedied by having a larger sample size. Higher levels of luteinizing hormone after red wine consumption compared to after white wine consumption, according to the authors, suggests hypothalamic up-regulation in response to the lower estrogen levels. Taking all results into consideration, the authors claimed that red wine is a nutritional aromatase inhibitor, and therefore beneficial in potentially reducing the risk of breast cancer in premenopausal women.
According to some studies, there is a 12% increased risk of breast cancer with the consumption of alcohol. Most studies do not take into consideration red and white wine separately, and those that do have found conflicting results. The results of this study show that red wine may not increase the risk of breast cancer as other types of alcohol do, as a result of the beneficial aromatase inhibitor properties that the red wine exhibits.
This study is not without its limitations, however. The sample size was relatively small, so some of the results that were found not significant or marginally significant (“trending”) may prove to be significant with a larger number of participants. Generally, the greater the variability of a particular variable (e.g. estrogen levels), the larger the sample size needed to detect significant differences between treatments. With the smaller number of participants, it’s also likely that the demographics of the group were not representative of the entire population (though, they did not report these data, so we cannot be certain). A study incorporating many different demographics is necessary to determine if the results of this study are applicable to other groups, or only this small subset of individuals.
The initial results of this small study seem to suggest an aromatase inhibitory effect of red wine in premenopausal women, but not white wine. This benefit may act to negate the negative effects of the increased risk of breast cancer after alcohol consumption, though more studies are needed to be certain.
I’d love to hear what you all think of this topic! Please feel free to comment below (any unapproved HTML tags will be deleted).
Source: Shufelt, C., Bairey Merz, N.,Yang, Y., Kirschner, J., Polk, D., Stanczyk, F., Paul-Labrador, M., and Braunstein, G.D. 2011. Red Versus White Wine as a Nutritional Aromatase Inhibitor in Premenopausal Women. Journal of Women’s Health 00: 1-4.
DOI: 10.1089/jwh.2011.3001
I am not a health professional, nor do I pretend to be. Please consult your doctor before altering your alcohol consumption habits. Do not consume alcohol if you are under the age of 21. Do not drink and drive. Enjoy responsibly!