Ruth A. Beckett is a wife and mother who last week committed herself to take a mystery pill every night for the next eight to 12 years. In this "double-blind" study, neither she nor the researchers giving her the pills knows whether they are estrogen or merely placebos.

"It's quite a commitment I'm making at the moment," she says uneasily as she completes the final paperwork at a Brookline office.

Like other post-menopausal women, Beckett had asked her doctor about hormone-replacement therapy. But she was faced with confusing responses.

"There was so little information," she says. "When women my age try to get information on whether to take estrogen, the information is not conclusive."

So Beckett enrolled in the Women's Health Initiative (WHI), the largest research study of women ever sponsored by the federal government. It is a 15-year, $628 million clinical trial sponsored by the National Institutes of Health (NIH).

At Brigham and Women's Hospital, a Harvard Medical School affiliate, WHI researchers are searching for explanations of the major causes of disease and death in post-menopausal women, including cardiovascular disease, cancer and osteoporosis.

They are examining the effects of hormone replacement therapy, low-fat diets and calcium and vitamin D supplements in women aged 50 to 79.

Dr. JoAnn E. Manson '75 is the principal investigator of the WHI at Brigham and Women's, one of the study's 16 nationwide vanguard centers responsible for program design and recruiting. She says she believes the study is desperately needed, since medical research has traditionally focused on men.

"Most previous clinical trials have been conducted in men only, and we now know that results from studies in men can't [always] be extrapolated to women," she says.

"[Men and women often] have different responses to diseases and treatment," Manson explains. "Certain diseases are more common or unique to women. In order to get answers, we need to study women directly."

Manson notes that ironically, the first randomized trial of a particular form of estrogen was performed solely on men, with the adverse affect of increasing the risk of coronary heart disease.

Health studies have usually been performed on all-male groups for economic reasons, doctors interviewed said. For example, since heart disease is more common in men than in women, researchers could follow smaller sample populations for a shorter period of time and find more data points if they limited their trials to men.

Manson also cites legitimate concerns of researchers that the menstrual cycle would alter data or that fetuses would be harmed if pregnant women were used in studies.

"But none of these reasons justify the exclusion of women from clinical trials, and I think that's being increasingly recognized," she says.

Although most of Manson's colleagues see the necessity of studies on women, some believe that strict quotas may hinder research.