Estriol: Its Weakness is Its Strength

By Olivia A.M. Franks, ND and Jonathan V. Wright, MD, Life Extension Scientific Advisory Board Member
Estriol, an estrogen that has virtually been ignored by the mainstream medical community, is
one of the three principal estrogens produced by the body. Estriol was originally thought to
have little significance due to its weak estrogenic activity when compared with estrone and
estradiol. Nonetheless, research has found that its weakness may very well be its strength.

Studies suggest that when the lower-potency estrogen, estriol, is administered topically, it
does not increase the risk of hormone-dependent cancers of the breast or endometrium
(uterine lining).1-3 However, having weaker estrogenic effects does not mean that estriol has
none of the benefits that come with more potent estrogens. Studies suggest that estriol
reduces symptoms of menopause, such as hot flashes and vaginal dryness, but with a better
safety profile compared with more potent estrogens.1,4,5 This makes estriol a better choice for
bioidentical hormone-replacement treatment regimes.

That is not all this ‘weak’ hormone is good for! Research suggests that estriol has benefits for bone density, heart health,  multiple sclerosis, and postmenopausal urinary tract health.6-12 In this article, we will review the attributes of this ‘weaker’ estrogen, and why this estrogen is currently in the news.