Yes, this is from wikipedia, yes i know that's not always a reliable source. Can anybody post a definitive answer to this though, can reservatrol stimulate breast cancer? Is it estrogenic?
Adverse effects and unknowns
While the health benefits of resveratrol seem promising, one study has theorized that it may stimulate the growth of human breast cancer cells, possibly because of resveratrol's chemical structure, which is similar to a phytoestrogen.  However, other studies have found that resveratrol actually fights breast cancer. Citing the evidence that resveratrol is estrogenic, some retailers of resveratrol advise that the compound may interfere with oral contraceptives and that women who are pregnant or intending to become pregnant should not use the product, while others advise that resveratrol should not be taken by children or young adults under 18, as no studies have shown how it effects their natural development."