Doctors have assumed that the female hormone estrogen offers natural protection against heart complaints, and is the reason why women suffer fewer attacks than men.

Because of this, hormone replacement therapy (HRT) has also been assumed to offer similar protection to women after the menopause.

But a major new study among 651 postmenopausal women has put paid to both assumptions. The study has discovered that the women's natural levels of estrogen gave no special protection against heart disease, and so presumably HRT cannot claim to offer any protection, either.

Researchers explained that the different levels of estrogen in pre and post-menopausal women was not a deciding factor because heart attack death rates at the age of 50, around the time the menopause occurs, did not change. In any event, they discovered that estrogen levels did not alter to any great degree after the menopause.

The study tracked the women, living in Rancho Bernardo, California, over a 19 year period, taking blood plasma before and after menopause.

Although natural estrogen levels played no part in determining heart disease, researchers confirmed earlier findings that important indicators included age and diabetes. Cholesterol levels and blood pressure were not major factors (BMJ, November 4, 1995).