AROMATASE INHIBITORS AND ESTROGEN DOMINANCE
by Peter D'Adamo, N.D.
Although we very often hear of health problems such as female menopause being
linked with low estrogen, there are many clinical and subclinical conditions
that can benefit from inhibiting the excess production of estrogen and
enhancing the production of testosterone.
Though we think of declining estrogen as the hallmark of menopause, it's
actually common for women to experience surges of abnormally high estrogen
levels during the menopausal and premenopausal periods, as well as earlier in
Estrogen dominance can start early on in a women's menstrual cycle. Young
women who suffer from this enter menarche with tremendously difficult
periods, and doctors sometimes give these teenage girls birth control pills
to help regulate the frequency and severity of their periods.
Some women will develop the estrogen dominance syndrome much later in life,
sometimes as a result of diet, liver impairment, or environmental factors or
also as a result of anovulatory cycles before menopause -- that is, menstrual
cycles in which no ovulation has occurred. Ovulation is necessary in order to
produce the corpus luteum, (which means "yellow body") that is found on the
surface of the ovary after ovulation. Surrounding the ripening egg, the
corpus luteum remains after ovulation to produce progesterone for the last
half of the menstrual cycle. Without ovulation, less progesterone is
produced, which can cause estrogen imbalance in some women.
Diseases or problems that are thought to be related to or affected by excess
estrogen and deficient progesterone in women are:
Fibrocystic breast disease
Certain types of PMS
Menstrual disturbances--irregular and heavy bleeding.
Endometriosis, the uterine tissue disorder, which is helped by the use of
Fibroids, a sign of excess proliferative capacity of the uterus, which may
not be balanced with sufficient progesterone.
We live in an estrogenic or feminizing environment. Certain chemicals in the
environment and our foods, one of which is DDT, cause estrogenic effects.
Although banned in 1972, DDT, like its breakdown product DDE, is an
estrogen-like substance and is still present in the environment. Chlorine and
hormone residues in meats and dairy products can also have estrogenic
In men, the estrogenic environment may result in declining quality
of sperm or fertility rates.
In women, it may lead to an epidemic of female
diseases, all traceable to excess estrogen/deficient progesterone.
Aromatase is an enzyme required for the conversion of androgens to estrogens.
Aromatase inhibitors thus decrease the concentrations of estrogens in the
body and are effective against tumors that depend on estrogen for growth.
They are usually used as second-line therapy (after tamoxifen) for the
treatment of breast cancer in postmenopausal women.
AROMATASE, an enzyme found in the liver, in responsible for the
conversion of the androgens ANDROSTENEDIONE and TESTOSTERONE into the
estrogens ESTRONE and ESTRADIOL. By inhibiting aromatase the body produces
less estrogen and maintains a higher testosterone state.
Clinically, there are a variety of reasons why doctors would prescribe an
aromatase inhibitor for women. These include:
Healthy breast tissue
Proper estrogen levels
Healthy lean muscle mass
In men aromatase activity increases with age, converting what little
testosterone is left into estrogen. It is perhaps this event that is most
responsible for the many symptoms of “male menopause,” and possibly even
enlarged prostates and prostate cancer.
In women, most of the research on
aromatase inhibitors addresses the treatment of clinical conditions known to
be linked with excess estrogen production or sensitivity. In the general
population, aromatase inhibitors are used by the bodybuilding community to
increase lean muscle mass and decrease body fat.
Clinically, there are a variety of reasons why doctors would prescribe an
aromatase inhibitor for men. These include:
Healthy prostate tissue
Proper testosterone levels
Healthy sperm count
The long-held theory of prostate cancer, that testosterone is bad stuff, and
even worse when it's converted to dihydrotestosterone, is gradually falling
A more prevalent current opinion is that prostate cancer has
more to do with estrogen than with dihydrotestosterone. It appears that many
men, as they get older, convert too much testosterone to estrogen and that
this excessive estrogen is the cause of prostate enlargement or prostate
For men, we're just beginning to recognize that the overproduction
of estrogen may be a large part of the problem. (We should remember, by the
way, that in both sexes, testosterone metabolizes to estrogen by the action
of aromatase. In women, of course, the great majority of the testosterone is
converted, whereas in men, it's the opposite: most of the testosterone in a
healthy man stays as testosterone, and only a little bit becomes estrogen.)
The reasons for an excess of estrogen in some men may be genetic or are
perhaps environmental - we've all heard about those environmental
ESTROGEN BLOCKERS AND AROMATASE INHIBITORS
Indole-3-Carbinols: These compounds, found in cruciferous vegetables like
cabbage, brussels sprouts, cauliflower, collards and broccoli, help to
transform dangerous estrogen into more benign forms, as recognized by the
National Cancer Institute.
They have also been shown to stop the growth of
breast-cancer cells by inhibiting the action of a specific enzyme.
Chrysin: Found in the herb Passiflora incarnata, the flavone chrysin is a
potent natural aromatase inhibitor. In a study published 1993 chrysin and 10
other flavonoids were compared to an aromatase-inhibiting drug
(aminoglutethimide). Chrysin was the most potent aromatase-inhibitor, and was
shown to be similar in potency and effectiveness to the aromatase-inhibiting
drug. The scientists conducting the study concluded by stating that the
aromatase-inhibiting effects of certain flavonoids may contribute to the
cancer preventive effects of plant-based diets. (1)
Apigenin: Found in most species of Chamomile, the flavone apigenin is also a
safe and effective aromatase inhibitor, with an inhibitory effectiveness
about equal to chrysin. (2)
Isoflavones: The isoflavones in soy, most notably genistein and diadzein were
shown in studies to be potent aromatase inhibitors (4)
An advantage to using plant extracts to boost testosterone in lieu of drugs
is that the plant extracts have ancillary health benefits. Chrysin, for
example, is a potent antioxidant that possesses vitamin-like effects in the
body. It has been shown to induce an anti-inflammatory effect, possibly
through inhibition of the enzymes 5-lipoxygenase and cyclooxygenase
AROMASTAT is an all natural blend of herbs shown in clinical studies to
inhibit the enzyme aromatase.* Aromatase is an enzyme found in the liver that
converts testosterone into estradiol and androstenedione into estrone. Thus,
its primary action is to convert steroid hormones into estrogen class
1. Pelissero C, Lenczowski MJ, Chinzi D, Davail-Cuisset B, Sumpter JP,
Fostier Effects of flavonoids on aromatase activity, an in vitro study. J
Steroid Biochem Mol Biol. 1996 Feb;57(3-4):215-23.
2. Jeong HJ, Shin YG, Kim IH, Pezzuto JM. Inhibition of aromatase activity by
flavonoids. Arch Pharm Res. 1999 Jun;22(3):309-12.
3. Kellis JT Jr, Vickery LE. Inhibition of human estrogen synthetase
(aromatase) by flavones. Science. 1984 Sep 7;225(4666):1032-4.
4. Kao YC, Zhou C, Sherman M, Laughton CA, Chen S. Molecular basis of the
inhibition of human aromatase (estrogen synthetase) by flavone and isoflavone
phytoestrogens: A site-directed mutagenesis study. Environ Health Perspect.
Abstract # 596
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