Your body produces 3 different estrogens: estrone, estradiol and estriol. Estriol (also known as E3) is the weakest of the 3 natural estrogens and was originally thought to have little significance. It has been virtually ignored by the mainstream medical community because it doesn’t have the quick, recognizable effects on the body that the stronger estrogens do. While estradiol (E2) will stop hot flashes within hours after applying to the skin, estriol takes much longer to affect you. However, current research has found that estriol offers a wealth of benefits without the dangers that sometimes accompany the stronger estrogens or the synthetic estrogens (such as Premarin).  Estriol can help relieve menopausal symptoms, protect your bones, rejuvinate vaginal tissue, benefit urinary tract health and correct vaginal dryness. It may also reduce cardiovascular risk and shows great promise in reducing brain lesions in multiple sclerosis patients.Estriol is the estrogen most commonly associated with pregnancy. In fact, during pregnancy levels of estriol are up to 1,000 times higher than normal when compared to non-pregnant levels. Women suffering from multiple sclerosis often see their symptoms get considerably better during pregnancy.But what about the risk of breast cancer? There have been lots of opinions and articles in the media relating estrogen use to increased risk of breast cancer. What they fail to tell  you is the type of estrogen studied. In a study funded by the U.S. Army and performed at the Public Health Institute in Berkeley, CA, researchers compared estriol levels during pregnancy with breast cancer incidence 40 years later. Results of the study showed that of the 15,000 women involved, those with the highest levels of estriol during pregnancy had the lowest incidence of breast cancer later on. Asian and Hispanic women typically have higher levels of estriol than other racial groups and interestingly have the lowest breast cancer rates.Estrogen has also been linked to endometrial cancer in the media. In one investigation, postmenopausal women were given oral estriol with no progesterone for 6 months. Oral estrone or estradiol are not advised because they can increase the risk of blood clots. Giving them unopposed (without progesterone) is not advised because it can increase the risk of endometrial hyperplasia (overgrowth…which can lead to cancer). However, all the study participants showed an improvement of symptoms; there were no strokes or blood clots and no endometrial hyperplasia (confirmed by endometrial biopsy). There were also no breast changes that would indicate a higher risk for breast cancer.Estriol has been shown to be the safest estrogen we can use to replace our body’s natural estrogens; it gives the most benefits with the lowest amount of risk. Ask your physician if estriol may be the right choice for you.