Estriol: Its Weakness is Its Strength. A listing of research article references.

“The summary article I included because it lists relevant research of estriol vaginal hormone replacement. The URL for further research is: http://www.lifeextension.com/magazine/2008/8/estriol-its-weakness-is-its-strength/page-01 “Bill Chesnut, MD

 

Estriol: Its Weakness is Its Strength

August 2008 By Olivia A.M. Franks, ND and Jonathan V. Wright, MD

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

 

SAFETY CONCERNS
Most of the research cited in this article used oral estrogen as the route of administration. However, for enhanced safety, topical estriol would be a better choice. Several studies have shown that transdermal estrogen confers less health risk as a route of administration than oral estrogen.3,21-25 Clinical experience of many doctors over the past 20-30 years suggests that transdermal estrogen is also more effective for some women. This is largely thought to be due to the ‘first-pass effect’—meaning that orally ingested drugs are often first metabolized in the liver, before having any activity in the body. Orally ingested estrogen hormones are among these drugs that are first metabolized in the liver before exerting their effects in the body. Physicians experienced in hormone replacement often observe that women treated with oral estrogens show high levels of estrogen metabolites in 24-hour urine specimens, suggesting that most of the orally ingested hormones are being excreted.

In addition, several studies suggest that bioidentical estrogen has less health risk when given with low doses of bioidentical progesterone.26,27

 

Estriol Reduces Markers of Cardiovascular Risk

Growing evidence suggests that estriol may offer protective benefits for the cardiovascular system. For instance, Takahashi et al. found that some women with natural menopause given 2 mg/day oral estriol for 12 months had a significant decrease in both systolic and diastolic blood pressure.1

Another study compared the use of oral estriol at a dose of 2 mg/day for 10 months in 20 postmenopausal and 29 elderly women. Some of the elderly women had decreases in total cholesterol and triglycerides and an increase in beneficial high-density lipoprotein (HDL).7

Estriol Improves Bone Mineral Status in Women With Osteoporosis

A Japanese study involving 75 postmenopausal women found that after 50 weeks of treatment with 2 mg/day of oral estriol cyclically and 800 mg/day of calcium lactate, women had an increase in bone mineral density, a decrease in menopausal symptoms, and no increased risk of endometrial hyperplasia (tissue overgrowth that may precede cancer).6

Similarly, Nishibe et al. investigated treatment of postmenopausal and elderly women with 2 mg/day of oral estriol and 1,000 mg/day of calcium lactate versus 1,000 mg/day calcium lactate alone. The bone mineral density significantly increased in women who received estriol, whereas the women who did not take estriol experienced a decrease in bone mineral density.7

Estriol Reduces Brain Lesions of Multiple Sclerosis

The high levels of estriol during pregnancy have been known to alleviate some autoimmune conditions due to its ability to shift immune response.9 For instance, Sicotte et al. at the Reed Neurological Research Center in Los Angeles investigated the effects of pregnancy-level doses of estriol (8 mg/day) in non-pregnant women with multiple sclerosis (MS). Cerebral MRI images showed a significant reduction of gadolinium-enhancing cerebral lesions from multiple sclerosis. These lesions increased when treatment stopped and decreased when treatment was restarted.28 Gadolinium is a contrast agent used in certain MRI studies; gadolinium-enhancing lesions are associated with an increased inflammatory response marking disease progression in patients with MS. Lowered amount of these lesions seen on MRI with gadolinium contrast would equate to a decrease in disease progression.

This effect may also apply to men with autoimmune conditions. Another team of researchers from the Reed Neurological Research Center in Los Angeles found that estriol treatment ameliorates experimental autoimmune encephalomyelitis (EAE) in males, compared with placebo treatment.29 EAE is an experimental demyelinating inflammatory disease that shares numerous characteristics with MS. Estriol treatment also resulted in a decrease of proinflammatory immune markers. This is very promising news for patients and their doctors who are struggling to treat challenging neurological conditions associated with inflammation.

Estriol Protects Urinary Health in Postmenopausal Women

Postmenopausal women who suffer from incontinence or recurrent urinary tract infections will be pleased to know that estriol offers benefit in the context of these troublesome conditions. In a prospective, randomized, placebo-controlled study, 88 women were given 2 mg intravaginal estriol suppositories (once daily for two weeks, then twice weekly for six months) or placebo. Of the women in the estriol group, 68% reported improvement in symptoms of incontinence. In addition, measurements of mean maximal urethral pressure and mean urethral closure pressure were significantly improved.10

In another randomized, double-blind, placebo-controlled trial, women with recurrent urinary tract infections (UTI) were given either intravaginal estriol cream (containing 0.5 mg estriol, once daily for two weeks, then twice weekly for eight months) or placebo. The incidence of urinary tract infection was dramatically reduced in the estriol group compared with placebo (0.5 versus 5.9 episodes per year).11