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Nobody likes the symptoms that come with perimenopause and menopause. Hot flashes, fatigue, depression, irritability, and insomnia are not fun! Could soy be the answer? Dr. Gordon Saxe, Director of Research and an Integrative Physician at the University of California, San Diego Center for Integrative Medicine, answered questions about soy’s effects on health that women in PM&M are dying to know the answers to!
A: Soybeans contain, among other things, several isoflavones (e.g. genistein, daidzein, equol) that have been the subject of much research. These isoflavones may – repeat may – be of benefit for the symptoms of PM&M (e.g. hot flashes, flushing, night sweats, sleep disruption, vaginal dryness, mood swings). At this point, the evidence is mixed that soy isoflavones offer relief. It seems that for every study showing a benefit, there is another one calling this into question. However, I have not seen any evidence that soy worsens these symptoms so for women who are suffering, I’d say soy is worth a try.
Q: There are so many ways to include soy in meals, too. You’ll have to give us some recipes you’ve found to be most delicious! Are there any other ways in which soy may be good for your health?
A: One very important potential benefit is that soy isoflavones may inhibit the development of atherosclerosis (the buildup of plaque that can block arteries) and possibly reduce the risk of heart attacks, the leading killer of both men and women. Of course, it should be pointed out that consumption of a whole food, plant-based diet – with or without soy – has been demonstrated to reverse atherosclerosis. Soy isoflavones may also inhibit the replication of tumor cells and several small studies have suggested that they may slow the progression of prostate cancer in particular. Soy isoflavones may also help prevent osteoporosis by stimulating bone formation and inhibiting bone resorption.
There is also scientific evidence that suggests possible benefits for a couple of other health issues affecting many women: infertility and hair loss.
Certain soy isoflavones (genistein and daidzein) – like the widely used fertility drug Clomid – have biochemical structures similar to estrogen and can therefore bind to and block estrogen receptors in the hypothalamus. With these receptors blocked, the brain doesn’t get the signal from the estrogen circulating in the bloodstream and is fooled into thinking that estrogen levels are too low. Like Clomid, these isoflavones – through their effects on the hypothalamus – cause the follicles in the ovaries to grow and mature and this, in turn, leads to increased ovulation and possibly increased fertility.
When there is a lack of ovulation, progesterone levels fall and the body responds by increasing production of the adrenal cortex hormone, androstenedione. Androstenedione is an androgen (male-like hormone) that, among other things, can cause male pattern hair loss. In women who have not gone through menopause and are still menstruating, soy isoflavones, by increasing ovulation and reducing androstenedione levels, may help restore normal hair growth. However, this is a gradual process and it may take 4-6 months to detect a noticeable improvement.
Q: I would definitely wait 4-6 months if it meant an improvement of my symptoms. Lots of women, however, are hesitant to include lots of soy in their diets because they hear it is connected to breast cancer. Does soy have an effect on the development of breast cancer?
A: This is a tricky subject!
Intake of soy has not been shown in epidemiologic (population) studies to be a risk factor for breast cancer. However, soy isoflavones such as genistein are known to bind to estrogen receptors and to cause effects in the body that resemble those of weak estrogens. Further, laboratory studies suggest that concentrated levels of soy isoflavones may stimulate breast and uterine hyperplasia – non-cancerous conditions to be sure, but ones that involve cell proliferation. While the concern that these compounds could be harmful to women with breast cancer (or pre-malignant breast lesions) is mainly theoretical, common sense dictates that it is probably not wise to administer concentrated forms of them to someone who suffers from a condition involving uncontrolled cell proliferation!
Whether or not concentrated soy isoflavones are harmful for breast cancer, there is another reason for women with breast cancer to be cautious about them. It turns out that because they can bind to estrogen receptors on breast cancer cells, they may interfere with tamoxifen, a drug used by many breast cancer patients. Tamoxifen, a hormonal therapy, works by binding to estrogen receptors on these cells and blocking them from binding circulating estrogen (a breast tumor promoter). By interfering with tamoxifen, concentrated soy isoflavones may allow more of the circulating estrogen to “slip through” and act on these cells.
While concentrated soy isoflavones may be of potential concern for breast cancer, whole soy foods, have been used as a part of the diets of women in Asia for centuries and yet Asian women have rates of breast cancer about 90% lower than their American and European counterparts. So, if whole soy foods are harmful, it’s not apparent in the rates. In fact, there is evidence that whole soy foods – particularly those that are fermented – may actually reduce the risk of breast cancer. For example, those Japanese women who regularly consume miso soup (soup flavored with miso, a fermented soybean paste) have rates of breast cancer even lower on the average than the already low rates in Japan.
So what should women with breast cancer do? Probably the best advice is to completely avoid concentrated soy isoflavones and restrict use to whole fermented soy foods. And it would also be smart and fun to explore recipes containing various beans and legumes (lentils, chickpeas, aduki beans, black beans, etc.) other than just soy.
Q: What is the best way to use soy? Are there any soy products that women should avoid?
A: In my opinion, the best way to use soy is in the form of whole fermented soy foods – such as miso, tempeh, tamari, and natto – as a regular part of the diet. Occasional use of tofu and sparing use of other non-fermented soy foods (soy milk, edamame, soy cheese, soy nuts, etc.) is probably ok for healthy individuals but I would recommend that most people – especially women with breast cancer – avoid soy shakes, powders, and pills that concentrate the isoflavones, at least until more research clearly establishes their safety.
Fermented soy foods, on the other hand, have been traditionally prepared and used safely in Asian cuisine and healing since antiquity. However, non-fermented soy foods other than tofu (e.g. soy milk, edamame, soy nuts, etc.) are high in trypsin inhibitor and impair protein digestion, leading to potential deficiencies of several amino acids and trace minerals. Fermentation deactivates trypsin inhibitor and it was not until the Chinese developed this process about 2500 years ago during the Chou Dynasty that soy foods were regularly eaten. Precipitation of soybeans with calcium sulfate (which precipitates tofu but leaves the trypsin inhibitor in the soak water) also reduces trypsin inhibitor but not to as great an extent as fermentation.
Q: Are there any other benefits to the use of fermented soy foods?
A: Yes, indeed!
Fermentation of soy makes the aforementioned isoflavones more bioavailable. Most of the isoflavones in non-fermented soy are bound to carbohydrate molecules known as glucosides. For example, the isoflavone genistein, when bound to glucosides, is known as genistin. The process of fermentation transforms it into the far more assimilable form genistein.
Fermentation also results in the formation of active cultures such as lactobacillus and bifidus. Most people think that they need to eat yogurt to obtain these active cultures in their diets. But they can also get them in whole fermented soy foods.
Finally, if that isn’t sufficient reason to consider incorporating fermented soy foods into your diet, consider this: research in Japan has shown that these foods – particularly miso – contain the natural chelating agent zybicolin, a compound that is effective in binding, detoxifying and eliminating industrial pollutants from the body. This even includes compounds such as radioactive strontium.
Imagine that . . . a food that can replace an unhealthy glow with a healthy one!
A huge thank-you to Dr. Gordon Saxe for his extensive information about soy’s effect on your health! Stay tuned for Dr. Saxe’s favorite soy recipes in early January for more perimenopause and menopause support–a great way to kick off your sumo-free new year and a delicious addition to your favorite menopause book, Shmirshky: the pursuit of hormone happiness!
Gordon Saxe, MD, PhD is the Director of Research and an Integrative Physician at the University of California, San Diego Center for Integrative Medicine in La Jolla, CA. Dr. Saxe can be reached at: firstname.lastname@example.org.