The Women's Health Resource. On the web since 1997.

Estrogen Replacement Therapy Helps Prevent Osteoporosis in Post-Menopausal Women


A recent study published in the October issue of Natural Medicine confirms several previous studies that suggest women who use estrogen replacement therapy after menopause are at a lower risk of osteoporosis than post-menopausal women who do not take estrogen. The researchers conducted a study with mice, revealing that the female hormone estrogen may double or even triple the natural death of osteoclasts-cells responsible for destroying bone. David Hughes, MD, of the University of Texas Health Science Center in San Antonio said the study shows that estrogen may prevent excessive bone loss before and after menopause by curtailing the life span of osteoclasts.

Osteoporosis is a degenerative bone disease that mostly affects post-menopausal women. It is estimated that one-third of women over age 50 have osteoporosis. When a woman reaches menopause (typically around age 50), her body produces less of the female hormone estrogen. Since estrogen helps maintain bone density , a decrease in the hormone will result in some bone loss. Though most people believe bone is a solid material, it is actually a living tissue that is continually destroyed by osteoclasts and rebuilt by osteoblasts. If this destruction/reconstruction process is unbalanced and bone loss is severe, women may experience symptoms of osteoporosis (such as broken or fractured bones, back pain, or curved spine).

All cells, except cancer cells, have a natural process of death (called apoptosis) to prevent uncontrolled growth. In addition to increasing the rate of cell death, estrogen also appears to protect against osteoporosis by stimulating osteoblasts-cells responsible for bone growth and repair. According to Dr. Hughes, the osteoblasts are stimulated to increase their production of a cell-signaling molecule called transforming growth factor beta-1 (TGF-b1). In another study, researchers found that blocking TGF-b1 from cells significantly decreased the rate of cell death, making women more prone to osteoporosis. Researchers also discovered that blocking TGF-b1 reduces the effectiveness of tamoxifen-a drug used to treat or prevent breast cancer in some women.

The development of a drug that mimics TGF-b1 to help promote bone growth and repair may result in a new and effective approach to preventing osteoporosis in post-menopausal women, said Dr. Hughes. Lawrence Raisz of the University of Connecticut Health Center reminded women that Hughes’ study has not yet been confirmed in humans. However, Dr. Raisz agrees that post-menopausal women do benefit from taking estrogen.

In addition to preventing osteoporosis, estrogen replacement therapy (also called hormone replacement therapy (HRT)) may prevent heart disease , delay Alzheimer’s disease , and improve insulin resistance in patients with Type II (adult onset) diabetes. Possible negative effects of estrogen replacement therapy include:

  • bloating
  • nausea
  • breast tenderness (during the first three to four months of treatment)
  • vaginal bleeding
  • fluid retention
  • weight gain depression
  • increased blood clotting
  • migraine headaches

Although studies have been inconsistent, there appears to be an emerging consensus that estrogen replacement therapy (HRT with estrogen alone) does not significantly increase the risk for breast cancer. This appears to be true for women who are on estrogen less than five years or who take less than 0.625 mg per day. After five years of HRT, a woman’s risk of breast cancer does increase, although the degree of risk is still uncertain. Click here for more information about HRT and breast cancer .

Additional resources and references