Several popular herbal medicines have been found to have significant oestrogenic effects, despite the fact that they are not commonly used to treat gynaecological problems.
Researchers from the University of Pittsburgh Cancer Institute (UPCI) looked at a number of herbal products used to treat a wide range of symptoms, and discovered alarmingly high levels of oestrogenic activity.
They presented their findings at the 93rd annual meeting of the American Association for Cancer Research held this week in San Francisco.
"Our results indicate that some herbal remedies demonstrate measurable oestrogenic activity, in spite of the fact that they are not traditionally used as such," said Patricia Eagon, associate professor of medicine at the University of Pittsburgh and principal investigator of the study.
"This is important since it suggests that some extracts may not be appropriate for women who have a family or personal history of cancers that are linked to higher levels of oestrogen, including breast and uterine cancer. While plant extracts can alleviate symptoms for a variety of conditions, women should practice caution when using them and may want to avoid their use for conditions in which estrogens are contraindicated."
Of the extracts studied, motherwort leaf, saw palmetto berry, rhodiola rosea root and red clover blossom were the most potent in terms of their oestrogenic activity, and extracts of maca root, cramp bark and tumeric root were the least potent.