Soy And Phytoestrogens During Menopause

What are Phytoestrogens?

Phytoestrogens are plant substances that chemically or functionally act like –or somewhat like—human estrogens. At times some of the phytoestrogens mimic the actions of estrogens—and at other times, some of the phytoestrogens act as antagonists—meaning the phytoestrogens don’t allow estrogen to perform its functions.


The coumastans and the isoflavones are two subtypes of phytoestrogens. These two subtypes are the more common types found in foods such as soy products (which contain diadzein and genistein). Red clover, for example is high in the isoflavone formononetin. Coumestans are found in high concentration in peas and beans. Resveratrol is another phytoestrogen found in red wine and grape skins that has been in the news lately as a supplement to promote heart health and as great anti-oxidant that is claimed to reduce the signs of aging.

Another subtype of phytoestrogens are the lignans—these are found in flaxseed, most whole grains and vegetables.

The phytoestrogens act by binding to receptors for estrogen—these are either the alpha (α) or the beta (β) receptor. As mentioned, some phytoestrogens act to mimic human estrogen (they are called estrogen agonists) and other phytoestrogens act to block human estrogen from binding (they are called estrogen antagonists). The phytoestrogens have been included in a very broad chemical category called endocrine disrupters—and this is the basis for some of the controversy around using phytoestrogens as a dietary and natural treatment during menopause.

Why is there such an interest in phytoestrogens during menopause?

Women in Asia have historically consumed a lot of soy products—and they have also historically had a lower risk of heart disease, breast cancer, osteoporosis, diabetes and obesity. And, most importantly for women in perimenopause and menopause, these Asian women have had fewer symptoms during the menopausal transition. They have had fewer disruptive hot flashes, problems with insomnia.

In 1999, the US Food and Drug Administration (FDA) approved the health claim that daily consumption of soy was effective in reducing the risk of coronary artery disease. 1 These factors, along with the increasing interest in using traditional and more natural approaches to easing the symptoms of menopause as well as the increasing scientific and medical data that the traditional herbal approaches really reflected the action of phytoestrogens caused more and more women to turn to these herbs—high in phytoestrogens—to reduce the hot flashes, prevent osteoporosis and to prevent heart disease.

That sounds great—so why the concern?

The concern is that since phytoestrogens are classified as endocrine disrupter—they may behave like some of the man-made endocrine disruptors such as Bisphenol A (BPA). This is a particular concern for those with breast cancer—the problem is that the studies that have been done to address whether soy and soy products increase the risk of breast cancer have been inconclusive. 2 The results varied and seem to have depended on the woman’s ethnic background, age and other characteristics. For example, in one study, increased soy intake significantly reduced the risk for breast cancer in Chinese women. Another study found that pre-menopausal women or Caucasian descent were protected, but Asian women were not!  3

So, what can you do? Soy in moderation appears, overall, to be a benefit:

“Given the evidence that adding soy foods to an already healthy diet may have modest but measurable benefits on bone and cardiovascular health, women without serious risk factors for breast cancer or a family history of breast cancer could likely incorporate soy into their diet without significant concern.”  4

What would be moderate use? Soy milk has been used by many women to reduce some of the symptoms of menopause—primarily the hot flashes. Moderate consumption of soy milk would be 6-8 ounces a day of soy milk or using soy milk in place of cow’s milk in a morning cereal. If a woman is at high risk for breast cancer (because of her own history or a family history), then, the current information indicates that that amount of soy would be safe. Every woman should also consult her health care professional. But, also be aware that your health care professional has an awful lot of information to keep up with—and unless they specialize in menopausal issues or breast cancer, they may need some time to research the topic on their own.

What about other herbs like Red Clover, Black Cohosh, Don Quai and others?

Well, firstread our articles on these specific herbs!

Second, know that research is indicating that many of the traditional herbs are helpful for many women—but not all the research is positive, or very conclusive. Part of the problem may be in the approach taken (how the study is designed, how many women participate, how the herb is given etc).

Third, if you decide you want to try an herbal product for menopause, please consult a medical herbalist, a naturopathic physician (who is trained in medical herbalism) or a traditional Chinese Medicine (TCM) practitioner. There are many, many products out there—and some of them are not what they are advertised to be! You should also tell your health care professional about any and all medications, supplements and herbs that you are taking.


  1. FDA. Food labeling: health claims; soy protein and coronary heart disease. Food and Drug Administration, HHS. Final rule. . Fed Regist 1999;64:57700–33.
  2. Pattisaul H, Jefferson W. The pros and cons of phytoestrogens. Front Neuroendocrinol 2010;31:400-19.
  3. Pattisaul H, Jefferson W. The pros and cons of phytoestrogens. Front Neuroendocrinol 2010;31:400-19.
  4. Pattisaul H, Jefferson W. The pros and cons of phytoestrogens. Front Neuroendocrinol 2010;31:400-19.

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