A decade ago, upwards of 15 million American women were using combination hormone replacement therapy (HRT) to help deal with their menopausal symptoms. Doctors also believed HRT protected women from a host of other issues, including heart attacks and osteoporosis.

That all changed in 2002, when researchers learned that HRT drugs actually increased a woman’s risk of cardiac problems, stroke, and breast cancer – and millions of women dumped their bottles of HRT. Now, further research...