Phytoestrogens: the Simple Facts…
The term “phyto-estrogen” has generated more confusion in women who are trying to achieve hormone balance than any other phrase. Most assume that the word “estrogen” infers a steroid hormone, that carries all the risks and side-effects that are posed by synthetic, environmental estrogens.
All hormones occupy hormone receptor sites, similar to the way a key fits into a lock. When a natural estrogen occupies an estrogen receptor, it “keys” the receptor site and causes a myriad of necessary activities to occur. When a synthetic estrogen (xeno-estrogen) occupies an estrogen receptor site, it also causes a myriad of reactions to occur at the receptor site, some of which imitate natural estrogens, but, many of which are harmful to the body. All synthetic estrogens have undesirable side-effects.
Similarly, phytoestrogens occupy estrogen receptor sites, however, just as a key blank will plug into a lock and not start your car, phyto-estrogens do not key or activate any significant activity to occur at the receptor level.
Phytoestrogens: How Beneficial?
Women are exposed to a broad spectrum of xenoestrogens (synthetic estrogens) from meat & dairy and from personal care products that are formulated with petroleum compounds (petro-chemicals). When phyto-estrogens occupy the estrogen receptor sites, they thereby prevent the “harmful” estrogens from plugging in and subsequent damage to the woman’s body. Phyto-estrogens, therefore, have a prophylactic or protective effect on women’s health.
Phytoestrogens: the Research…
In the lab, phytoestrogens can stimulate the growth of breast cancer cells. But in human studies, scientists have not found that diets high in soy increase breast cancer risk. In fact, most have found the reverse.In a report in The Journal of the American Medical Association in 2009, scientists who looked at 5,042 people in the Shanghai Breast Cancer Survival Study found that soy was linked to a significantly lower risk of breast cancer recurrence and mortality. But the study, while encouraging, was carried out in China, so questions lingered about the extent to which the findings applied to women elsewhere.
In a more recent multiyear study, published in May in The American Journal of Clinical Nutrition, scientists followed nearly 10,000 breast cancer survivors, many of them in the United States. They found that women who ate the most soy had lower rates of cancer recurrence and mortality.Though the findings reflect only a correlation, they suggest that the concerns about soy and breast cancer may be unfounded.Research shows that women in countries with a high consumption of phytoestrogens may have a lower risk of breast cancer. In a report published in CA: A Cancer Journal for Clinicians in 2007, scientists note that exposure to phytoestrogens in childhood or early adolescence may help protect against future incidence of breast cancer.a 2001 research review published in Archives of Internal Medicine, investigators analyzed 74 studies on phytoestrogens and concluded that there isn’t enough evidence to recommend the use of phytoestrogens in place of traditional HRT. However, the review’s authors note that “evidence for the potential health benefits of phytoestrogens is increasing.”Phytoestrogens have some beneficial effect on bone mineral density, insulin resistance, and cholesterol levels among women undergoing menopause, according to a review published in Fertility and Sterility in 2007. The review’s authors sized up 21 studies, finding no evidence that phytoestrogens can protect against breast cancer, bone fracture, or cardiovascular disease in postmenopausal women.Phytoestrogen seems to be the new buzzword these days when discussion turns to menopause and alternatives to hormone replacement therapy, but what are phytoestrogens and how do they affect us? The word, phytoestrogen, comes from “phyto”, meaning plant, and “estrogen” due to their ability to affect estrogenic activity in the body.
It is important to know that although phytoestrogens may have some similar actions to estrogens, they are not true estrogens as our bodies produce. Phytoestrogens are a group of compounds found in plants that influence our own estrogen activity. There are several types of phytoestrogens found in plants and although most are non-steroidal, some plants do contain minute amounts of steroidal estrogens that match those produced in our bodies. The following plants contain steroidal estrogens (estradiol, estrone, or estriol) in small amounts: French bean, pomegranate seed, apple seed, date palm, licorice, and rice. Most non-steroidal phytoestrogens belong to the family of compounds called phenolics. These include the flavones, flavanones, flavanols, isoflavones, lignans, and coumestans, which are found in numerous plant sources.
Isoflavones, such as those in soy, are especially prevalent in legumes, like soybeans, and plants such as red clover. Phytoestrogens can either act as weak estrogens, or provide precursors to substances that affect our estrogen activity. To understand how phytoestrogens work, it is important to understand a little about how our hormones work in general. Viewed simplistically, hormones are typically manufactured and released by various glands, organs, and tissues into our blood stream where they can then travel to target tissues.
Environmental or Xenoestrogens: Two Sources
These target tissues contain receptor sites that are specific to certain hormones. When the hormones bind to the receptor sites, they can initiate an effect on the target tissue.
For example, estradiol, our body’s strongest estrogen, can be released from the ovary and travel to any number of target tissues, including the breast and the uterus. At the breast, estradiol can bind to receptor sites and increase cell division; at the uterus, estradiol can cause the endometrial lining to thicken. These receptor sites are not so specific that other substances can’t bind to them. However, just because a substance can bind to a receptor site doesn’t mean it will have a positive effect on the target tissue. Such is the case with Tamoxifen®, a drug that is used as a treatment for breast cancer. Tamoxifen® can bind to estrogen receptors in the breast without causing an increase in cell division as an estrogen would, thereby acting as an estrogen “blocker.” At the same time, it can bind to receptors in the uterus and cause proliferation (growth) of the endometrium. In other words, Tamoxifen® can have an anti-estrogenic effect on the breast, but have a pro-estrogenic effect on the uterus.
Phytoestrogens, such as fermented soy, can bind to estrogen receptors in our bodies and have either pro-estrogenic effects, or anti-estrogenic effects on the target tissues. How it affects the tissues depends in part on how much estrogen our bodies are already producing and how saturated our receptor sites are. If our estrogen levels are low, as in menopause, empty estrogen receptor sites can be filled with phytoestrogens, which can exert an extremely weak pro-estrogenic effect (Phytoestrogens may be anywhere from 1/147th to 1/1000th the strength of the body’s natural estrogen.). If our estrogen levels are high, as in some women who suffer from PMS and endometriosis, then phytoestrogens can compete with our own estrogens for binding to receptors. When the phytoestrogens are successful, they decrease overall estrogenic activity because their effect on the target tissues is less than if estradiol had been allowed to bind.
Other factors that can affect phytoestrogen activity, besides the ability to bind to receptor sites, include:
- how long a phytoestrogen remains bound to the receptor
- how rapidly it is broken down and removed from the bloodstream
- how it affects other aspects of estrogen load, such as levels of sex steroid hormone binding globulin (SHBG).
SHBG binds to hormones in the bloodstream and acts as a regulator of protein-bound, or inactive hormones.
There are hundreds of plants that contain phytoestrogens. Some of the more well known include red clover, licorice, soybeans, flaxseeds, black cohosh, and alfalfa. Historically, many of these plants have been used to regulate hormones and control fertility. Even animals have been known to graze selectively on plants to enhance or diminish fertility. Much of the early research on phytoestrogens was done with animals and interest was likely sparked by the observation that sheep that grazed too much on clover became temporarily infertile.
Recently, there has been a resurgence of phytoestrogen research as more women have demanded options to conventional hormone replacement therapy. Some studies report positive findings on the reduction of bone loss in women supplementing with soy phytoestrogens. Other research points to a reduction of cardiovascular disease risk similar to that seen with estrogen replacement therapy (ERT). Furthermore, epidemiological studies comparing native Asian women to other cultures have suggested that the high phytoestrogen content of their diets may be responsible in part for their low rate of breast cancer, and the ease with which Asian women pass through menopause.
Certainly, more studies on women using phytoestrogens need to be done to establish both benefits and risks. However, given the bulk of information available, phytoestrogen use can be considered a relatively safe method of affecting estrogen activity given the options currently in practice.
Plant estrogens, (phyto-estrogens) exert beneficial, protective influence against the tsunami of harmful estrogens everywhere in our environment and foods. Supplementing with a properly formulated bio identical progesterone cream will significantly balance the potential harmful effects from those estrogens.