Oestriol 25 August 2009
Oestriol is the main oestrogen produced by women and occurs in very high levels in pregnancy (1000 times higher than non-pregnant levels). Unlike the other oestrogens (present in much smaller amounts) oestrone and oestradiol, oestriol decreases a woman’s risk of breast cancer. This is because oestriol has been found to have both pro-oestrogenic and anti-oestrogenic effects. A study published in the November 1997 edition of the journal Molecular Endocrinology found that when oestriol was given with oestradiol, the oestradiol specific stimulation of oestrogen receptors was decreased i.e giving oestriol with oestradiol makes oestradiol much less dangerous. A study published in the May 1989 edition of the journal Cancer found that both oestriol and tamoxifen had protective effects against radiation induced breast cancer.
In all studies ever done on transdermal oestriol it has not been found to increase the risk of any cancers. A study published in the May 2000 edition of the journal Human Reproduction found no changes to the breast or endometrium in 53 women using oestriol for 1 year. A study published in the May 1999 edition of the Lancet found no changes to the endometrium over 5 years. Other studies have shown improvement in bone density and blood pressure with oestriol.
Oestriol may have a therapeutic benefit in addition to its use in hormonal restoration. It was discovered that multiple sclerosis (MS) frequently goes into remission when oestrogen levels are high. In one study published in the October 2002 edition of the journal Annals of Neurology, large doses of oestriol (8mg) were given to 12 non-pregnant women with MS. After 3 months, MRI scans showed an 82% decrease in numbers of MS lesions and a 79% decrease in the volume of the lesions. Changes were particularly profound in the relapsing group and less in the slowly progressive group. Oestriol can also be effective for women with other autoimmune diseases including lupus, rheumatoid arthritis and type 1 diabetes.
Oestriol has also been shown to be effective in urinary health of post-menopausal women. A study published in the January 2004 edition of the journal Menopause, 68% of women using 2 mg intravaginal oestriol reported improvement in symptoms of incontinence. Another study published in the September 1993 edition of the New England Journal of Medicine found a dramatic reduction in the incidence of urinary tract infections in women using 0.5mg of intravaginal oestriol cream twice weekly.
Despite the safety data on oestriol it should NEVER be used without progesterone as well. Studies published in the May 1993 and January 2003 editions of the journal Fertility and Sterility have shown the extra protective benefit of the simultaneous administration of progesterone with oestrogens.
More information on oestriol can be found in my newsletter on breast cancer prevention.