Regular alcohol consumption raises breast cancer risk, except for red wine, which has the opposite effect when consumed in moderation, researchers from Cedars-Sinai Medical Center in Los Angeles reported in the Journal of Women's Health. The authors explained that the chemicals in the seeds and skins of red grapes slightly reduce estrogen levels and raise testosterone among premenopausal females - thus reducing their breast cancer risk.
The authors stress that it is the red grape that has the beneficial compounds, and not just red wine. They suggest that women should consider red wine when choosing an alcoholic beverage to consume, rather than encouraging wine over grapes.
This study contradicts in part a widespread belief that the consumption of all types of alcoholic drinks raises a woman's chances of developing breast cancer, because alcohol raises estrogen levels, which in turn encourages the growth of cancer cells.
However, the researchers found that premenopausal women who consumed eight ounces of red wine every evening for approximately a month, had lower estrogen and higher testosterone levels. They tried out the same with another group of women, but they had to consume white wine - it did not have the same effect.
Moderate female alcohol drinkers should perhaps reassess their choices, the authors suggested.
Study co-author, Chrisandra Shufelt, MD, wrote:
"If you were to have a glass of wine with dinner, you may want to consider a glass of red. Switching may shift your risk."
There are over 230,000 new diagnoses of breast cancer each year in the USA - it is the leading type of female cancer in the country, the authors wrote. Approximately 39,000 adult females died from breast cancer in 2011, says the American Cancer Society.
The study involved 36 premenopausal females. They were randomly selected into two groups:
- The red wine group (Cabernet Sauvignon)
- The white wine group (Chardonnay)
For one month, they drank eight ounces of their designated wine every evening. During the second month they swapped groups, i.e. the women on white wine during the first one switched to red wine during the second month. Blood was collected from each participant four times, twice each month, to check for levels of hormones.
The scientists wanted to find out the ingredients of red wine might imitate what aromatase inhibitors do. Aromatase inhibitors are drugs that inhibit aromatase, an enzyme which is involved in estrogen levels. Aromatase inhibitors are used in breast cancer therapy.
They found that red wine lowers estrogen levels, which in turn should stem cancer cell growth. They added that test tube studies had indicated the same thing.
Co-author Glenn D. Braunstein, MD, explained that even though white wine (grapes) appears to lack the protective elements found in red wine (grapes), this does not necessarily mean that white wine raises breast cancer risk.
"There are chemicals in red grape skin and red grape seeds that are not found in white grapes that may decrease breast cancer risk."
Braunstein added that a larger study is needed to determine how safe and effective red wine might be in reducing breast cancer risk.