April 24 -- THURSDAY, April 23 (HealthDay News) -- More research is needed to determine whether grape seed extract lowers hormone levels in postmenopausal women and provides protection against breast cancer, say researchers at the City of Hope cancer center in Duarte, Calif.
Because studies have suggested that grape seed extract inhibits aromatase, an enzyme that helps in estrogen production, the researchers looked at whether grape seed extract supplements could lower hormone levels in postmenopausal women.
What they found was a dramatic and sustained decrease in one patient with high baseline estrogen levels. But variable baseline hormone levels in the participants prevented them from reaching firm conclusions, they said.
Their findings were presented at the annual meeting of the American Association for Cancer Research, in Denver.
"We found that there are many variables that affect a woman's hormone level, including diet, concurrent medications and other supplements," the study's leader, Dr. Melanie Palomares, an assistant professor of cancer screening and prevention, said in a City of Hope news release.
"It was difficult to ascribe changes observed so far directly to the grape seed extract supplements, though three of the seven participants treated on the highest dose level had results showing promise," she said. "Our pharmacokinetic observations in this trial merit further investigations to evaluate the prevention benefits of grape seed extract."
Palomares is continuing the research with higher doses of grape seed extract in more carefully selected women. Once the most appropriate dose is determined, she plans to conduct a follow-up clinical trial to measure how grape seed extract affects breast tissue risk biomarkers.
The U.S. National Cancer Institute has more about breast cancer prevention.
SOURCE: City of Hope, news release, April 21, 2009