Aromatase–Part Two:  Natural Aromatase Inhibitors

Aromatase–Part Two:  Natural Aromatase Inhibitors

In the previous newsletter we examined how both genders commonly have hormonal issues as they age. And we discovered that, by dampening the enzyme aromatase in the body, it is possible for women to reduce the side effects of too much, or the wrong kind of, estrogen, and for men to prevent the breakdown of testosterone into estrogen, and other detrimental metabolites.  While the medical profession uses anti-aromatase drugs, there are many natural substances which have been tested and proven to inhibit aromatase, which we will now explore. Here in Part Two, we will examine commercially available ingredients that can serve this purpose.

Herbal Extracts and Supplements

Citrus Bioflavonoids

Citrus bioflavonoids have been well studied, especially the flavonoids naringin, naringenin, and quercetin, all of which have been found to have strong anti-inflammatory and antioxidant activities. One of these, naringin, has been shown to be “beneficial for the treatment of obesity, diabetes, hypertension, and metabolic syndrome”.   (Source)

However, for our purposes we refer to the conclusion of one particular study: “Overall, this study suggests an antitumor potential for naringenin, naringin and quercetin isolated from citrus peels in breast cancer via possible modulation of estrogen signaling and aromatase inhibition suggesting their use in pre- and post-menopausal breast cancer patients, respectively.”   (Source)

The best way to get naringin, along with some quercetin and other flavonoids, is by drinking (organic) grapefruit juice, though both naringin and quercetin are also available in supplemental form.


DIM (diindolylmethane) is found in most cruciferous vegetables, including broccoli, brussels sprouts, cabbage, cauliflower, and turnip greens. In these vegetables we find it in the form of I-3-C (indole-3-carbinol), which is transformed into DIM in the body, and DIM has been shown to inhibit aromatase.  (Source)  Both DIM and I-3-C are available in supplement form. Cruciferous vegetables also contain substances called glucosinolates. During the process of “glucuronidation”, these substances facilitate the breakdown of estrogen into other metabolites, which are easier for the body to expel, thus helping to reverse estrogen dominance.

Calcium D Glucarate

Cruciferous vegetables, as well as apples, grapefruit, and oranges, contain a natural calcium salt called calcium-D-glucarate, “another natural aromatase inhibitor that blocks glucuronidase activity in the bowel”.   (Source)

(“Glucuronidase is a bacterial enzyme which can limit the excretion of compounds from the body such as medications, hormones, neurotransmitters and environmental toxins by reversing a detoxification process known as glucuronidation.”  Source)

Calcium D glucarate helps the liver perform conjugation processes, whereby the liver breaks down toxins, including excess hormones, allowing them to be excreted more easily. Thus, it is considered to help prevent certain types of cancers, especially breast and prostate cancers. Like the other substances mentioned, calcium d glucarate is available in supplemental form.

Ginkgo Biloba

I was surprised to find ginkgo on the list of anti-aromatase agents, but it is a nice bonus to have improved circulation and memory as a byproduct of using this herb to inhibit aromatase. It is, however, not quite that simple.  Ginkgo biloba has been used in herbal medicines for thousands of years, and marketed to us for decades. Unfortunately, years ago I ran across a study which showed that most ginkgo supplements were inferior. Whereas the German, clinically tested product performed very well, including favorably altering brain wave frequency, most of the cheaper products did very little, and none of them affected brain waves.

At that time, the German trademarked product (Ginkgold) was very expensive and the market was being flooded with cheap products that, to the unaware consumer, looked to be identical: that is they all claimed to be standardized to 24% flavone glycosides and 6% terpene lactones. This has bearing on the use of ginkgo for inhibiting aromatase.

The clinical study we are examining here found that a standardized G. biloba extract known as EGb 761, “inhibited aromatase and exerted antitumor effects on breast cancer cells both in vitro and in vivo. These findings suggest that EGb761 may be a useful aromatase inhibitor for the treatment of estrogen-sensitive breast cancer”.  (Source)

All well and good, but can we even acquire this miraculous ginkgo extract? A little more research was required.  EGb 761 is a standardized extract of Ginkgo biloba leaves, and like all half decent ginkgo extracts has antioxidant properties, and contains approximately 24% flavone glycosides (primarily quercetin, kaempferol and isorhamnetin) and 6% terpene lactones. However, as mentioned above, simply providing 24% flavones and 6% terpenes is not sufficient to guarantee that a ginkgo product is effective.

“EGb 761, which was originated by Dr Willmar Schwabe Pharmaceuticals (Germany), has been available in Europe as a herbal extract since the early 1990s. However, products containing EGb 761 are not approved for use by the US FDA.”

Fortunately, “Nature’s Way in the US (and Canada) distributes and markets a standardized extract of Ginkgo biloba leaves (the EGb 761 Formula) under the name Ginkgold.”   (Source)

Grape Seed Extract

Grape seed extract contains high levels of procyanidin dimers (a specific type of proanthocyanidin, which are a class of flavonoids) that serve as a potent inhibitor of aromatase.

“This extract has been shown to act as an aromatase inhibitor, or estrogen blocker, in postmenopausal women at high risk for breast cancer. It works in women with a breast cancer risk and may also work for men with estrogen dominance.”   (Source)


I believe in supplementing with melatonin since it is suppressed in humans by exposure to electro-magnetic pollution (something I covered in detail in Health Secrets Volume 2), and those of us living in cities are constantly bathed in electro-magnetic fields.

“Melatonin is known to suppress the development of endocrine-responsive breast cancers by interacting with the estrogen signaling pathways. In human breast cancer cells and peritumoral adipose tissue, melatonin downregulates aromatase, which transforms androgens into estrogens.”  (Source)

Nettle Root

Nettle root (not leaf, which is mostly used for allergies) is a standard herbal go-to for prostate problems, and is found in many prostate formulas. Studies have confirmed that nettle root will reverse BPH (benign prostatic hyperplasia), the condition that causes men to get up at night to pee frequently.   (Source)

Nettle root is also found in products designed to enhance libido as it contains substances that block testosterone conversion into estrogens, thus allowing more “free” testosterone to circulate (increasing libido), while protecting the prostate from excess estrogen. For those with estrogen dominance, or prostate problems, the proven ability of nettle root extracts to inhibit aromatase is a potential life saver.    (Source)

Nowhere is the “life saving” potential of nettle root more apparent than in a study which proved “the antiproliferative effect of stinging nettle roots on human prostate cancer cells, observed both in an in vivo model and in an in vitro system”.   (Source)

(Antiproliferative: of or relating to a substance used to prevent or retard the spread of cells, especially malignant cells, into surrounding tissues.)


Resveratrol is a polyphenolic compound originally isolated from grape peel, but now commercially extracted from Japanese Knotweed. Because of its structural resemblance to estrogen, resveratrol’s effects on estrogen receptors have been well studied. In one study, designed to determine how resveratrol affects the expression and enzyme activity of aromatase, it was discovered “that pharmacological dosage of resveratrol inhibited aromatase at both the enzyme and mRNA levels”.   (Source)

A superior form of resveratrol to supplement with is the liposomal form, found in NutriStart’s Liposomal Curcumin/Resveratrol product.


As this newsletter kept expanding, I went from one to two newsletters, and have now found that it requires a third part. Therefore, Part Three will cover those commonly available foods that have proven to have anti-aromatase properties.

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