1.   After menopause, it is common for women to begin taking estrogen to prevent osteoporosis, the potentially disabling disease characterized by bone loss.

2.   In addition to protecting against heart disease and brittle bones, estrogen prevents hot flashes and other symptoms of menopause, and may help preserve mental sharpness as well.

3.   Pearson said that, in her opinion, no woman should be taking estrogen to prevent heart disease outside of a clinical trial asking if it has that effect.

4.   Researchers have identified a key step in how the hormone estrogen prevents the devastating bone-weakening disease osteoporosis in older people.

5.   The paper added that although estrogen clearly prevents bone loss, whether that translates into preventing fractures has not been studied in a large controlled trial.

6.   They were surprised, she said, telling her that they had thought that it was well known that estrogen prevented heart disease.

7.   Whether estrogen prevents heart disease remains unanswered.

8.   Still, estrogen can prevent bone loss and add bone mass, and it can prevent heart disease, Siris said.