Medically Reviewed by Dr. Emma Pollon-MacLeod, ND
Phytoestrogens, Estrogen Detoxification and Hormone Balance
What Are Phytoestrogens?
Now that we have an understanding of xenoestrogens, we are going to shift our focus to phytoestrogens. Phytoestrogens are plant‐derived dietary compounds, found in a wide variety of foods, especially in soy. They represent a diverse group of naturally occurring chemicals with structural similarity to 17‐β‐estradiol (E2), the primary female sex hormone1, otherwise known as estrogen. As a result, they have the ability to bind to both estrogen receptor alpha and beta (ERα and ERβ); thus, impacting the effects of naturally occurring estrogen in the body. Albeit much weaker with respect to the binding capacity, the sheer fact that they have the ability to bind to either receptor has the scientific community questioning their impacts on human health.
Unlike synthetic xenoestrogens aka endocrine disrupting chemicals (EDCs), phytoestrogens have been documented to have health-promoting effects; however, in some cases, the opposite has been shown, which is why so many are left extremely confused as to the safety of these naturally “estrogenic” foods. Indeed, soy is almost universally acknowledged as a phytoestrogen food and one of the most widely grown and consumed crops globally, but there are also a large variety of common food staples that are classed as phytoestrogen foods that are consumed daily throughout the world. In short, we humans consume a lot of these “estrogenic foods,” so it is important to gain a clear understanding of exactly what they are and how they impact human health by critically examining data and not just following someone’s opinions on phytoestrogens per se.
Unfortunately, like most things hormonally related, phytoestrogens and their impacts are not so black and white. Their understanding is accompanied by a high degree of complexity, so let’s dig deeper into the research and biochemistry of phytoestrogen foods.
Different Kinds of Phytoestrogens
The major groups of phytoestrogens present in the human diet are lignans, coumestans, prenylflavonoids, and flavonoids. Isoflavones are a type of flavonoid wherein genistein and daidzein are most concentrated in soy and red clover. Together, these make up some of the most researched phytoestrogen compounds.
Phytoestrogen Food List
Lignans: flax, sesame, sunflower, pumpkin and poppy seeds, whole grains, fruits and vegetables, and legumes (cashews and peanuts)
Coumestans: alfalfa and clover sprouts, split peas, pinto beans, and lima beans
Prenylflavonoids: hops and beer
Flavonoids: berries, citrus fruits, grapes, grains, nuts, and legumes
Isoflavones: soy and red clover
The Varying Effects Of Phytoestrogens
As you can see, many different phytoestrogens are not only consumed regularly, but daily throughout the world, so why are their health-promoting benefits a source of ongoing debate? By and large, this has to do with exactly how they interact with ERs. As stated, humans have both ERα and ERβ present throughout the body. These ER subtypes have different roles in gene regulation, cancer biology and therapy.1
Their concentrations can also vary depending on which organs and tissues they are located in and they often have different, even opposite functions. Again, this is very complex, but the data to date confirms that in most cases, activation of ERβ is very common with soy and other phytoestrogen foods. This is a very important distinction, seeing as in many cases, ERβ is associated with “anti-estrogen” effects, meaning that protection from estrogen dependent cancers has been demonstrated. So how exactly does this happen?
Read Part 1 now. Click here.
As discussed in Part 1 of this series, estrogen is responsible for tissue growth and cell division and is kept in check by progesterone. That said, if it goes unchecked, cells and tissues would just keep growing, which is why it is so important to ensure all of your hormones are in balance. What is much less understood though is that activation of ERα is what is commonly associated with the proliferation of cells and tissues, creating another layer of complexity to estrogen’s role in cancer formation. ERα activation in breast and uterus has been shown to enhance cell proliferation, necessary for growth and tissue maintenance, but may also play a role in the unlimited growth of, in particular, ERα‐dependent breast tumours. ERβ has been shown to counteract the ERα‐mediated stimulation of cell proliferation.1
Interestingly, even though soy’s genistein and daidzein are some of the most studied phytoestrogens, the prenylflavonoid, 8‐prenylnaringenin is the most potent phytoestrogen known.1 It is present in hops and beer; thus, widely consumed throughout the world, yet the focus and respective controversy seem to largely fall to soy and its compounds. So why exactly is soy such a controversial phytoestrogen food?
Soy—Friend or Foe?
It appears we have finally reached the juncture where a pertinent query arises within nutritional sciences: “to soy or not to soy,” that is the question. Well, again, the answer is not so black and white and requires some historical context. Although soy isoflavones have been demonstrated to have five times the affinity for ERβ and thus often promoted for their cancer-protective effects, additionally, they have been shown to have no protective effect against cancer. For every positive effect that soy demonstrates in varying types of research, the opposite has been shown.
The use of soy‐based preparations has been proposed for the prevention and treatment of certain types of cancer, such as for the prevention and treatment of breast cancer in women and prostate cancer in men. In contrast, clinical studies have reported data that suggest that isoflavones may via their oestrogenic and proliferative effects possibly raise breast cancer incidence in sensitive individuals.1
Although the adverse effects of soy with respect to infertility are commonly cited, these adverse effects have been mainly suggested based on data from in vitro, animal or epidemiological studies. Clinical studies often report the absence of adverse effects.1 It has been implicated in complications with thyroid function due to its goitrogenic effects. In order to understand these seemingly contradictory results clearly, we have to go back to the beginning.
Soy has been cultivated and consumed for nearly 3000 years by East Asian populations. It only became popular in European and Western populations within the last century, where it began to increase in popularity in the 1960s; therefore, a newer food crop to most parts of the world by comparison.
The so called ‘Japanese Phenomenon’ is connected to a lower incidence of specific chronic diseases in the Japanese compared with the Western population due to a higher intake of soy foods from early life onwards. The fact that the prevalence of breast cancer in daughters of migrated Japanese Americans became similar to that of Caucasian Americans after changing their food habits is in line with this observation.1
This correlation has largely been the basis for the frenzy around soy as a “superfood” as touted by the “to soy” camp. Unfortunately, there is so much to this seeming correlation and the impacts of isoflavones that most that sing the soy gospel fail to mention. Firstly, because phytoestrogens have the ability to bind and interact with ERs throughout the body, albeit weaker than that of E2, they have the ability to impact transcription aka gene expression as seen with steroid hormones.
As a result, there is a logical argument that due to the ancient history of soy in East Asian populations, there has been somewhat of adaptation with respect to which genes have been “turned on or off” via consumption of soy which is then passed on to the next generation and so on. Indeed, there has not been a longitudinal study to prove this, but it certainly helps to explain why particular benefits of soy are seen mostly in East Asian segments of studies and not in other racial segments within the same studies.
Secondly, gut health plays way more of a factor with respect to the benefits of soy than most are aware of. Interestingly, it has been confirmed that even acquiring the benefits of phytoestrogens is based on what bacterias exist in the gut of the populations that consume them! Yep, you read that right—reaping the full benefits of soy is linked to the health of your gut and the types of bacteria that populate it. Just another confirmation that everything comes down to gut health.
Let’s not forget that the microbiome plays a significant role in estrogen metabolism and detoxification. Like steroid hormones, phytoestrogens also form metabolites in the gut. In fact, daidzein has two metabolites, S-equol and O-DMA, the former having much higher activity than its precursor, while the latter is less active. Some authors have actually divided the global population into 3 categories:
- Producers of O-DMA
- Producers of Equol
Thirdly, it appears that non-producers are the most common, where O-DMA producers are the second most common, while equol producers are the least common. If this categorization is accurate, then it suggests that the majority of people are non-producers, meaning that they will not fully reap the benefits of soy. Is it possible that along with an “adaptive” capacity, that the majority of East Asians are producers of equol, which is why the benefits of soy—especially with respect to specific cancers are observed so consistently in this population segment?
With respect to the observed “Japanese Phenomenon,” it is also critical to ask the following: Is soy really the prime differentiating factor or just a part of a series of factors that drive what is commonly seen in Japanese and other East Asian populations? Is it possible that high consumption of fruits and vegetables, fiber, seafood (fish and sea veggies), starchy rice (resistant starch), medical mushrooms and the powerhouse known as green tea may also be significant factors as to how these populations stave off certain diseases? It is common knowledge that the characteristics of an Asian diet differ from a Western one in numerous ways, with soy intake only representing a small proportion of this difference.2
Although soy may be ditched when these populations emigrate to the West, how much of the other components to their diet change en route to assimilation to the dominant culture? The Standard North American Diet (SAD) is pretty much devoid of the aforementioned whole food staples, so it is no wonder that cancer and other degenerative disease rates increase. Remember, green tea alone is such a potent source of highly unique antioxidants known as catechins that have been cited repeatedly for their anti-carcinogenic effects; thus, it is not unreasonable to conclude that abandoning it in lieu of sugar-laden beverages would have negative health impacts.
Lastly, it is important to bear in mind that even human studies can have shortfalls, especially in population studies. Unfortunately, in these cases, there are few controlled variables coupled with an array of variables that are not controlled or taken into account that impact the results of the study. For example, it is unlikely that lifestyle factors like xenoestrogen load and how much alcohol, beer, in particular, were considered in all of the studies that showed negative impacts of soy. Indeed, they may have in some cases; however, because the carcinogenicity of xenoestrogens has been documented, is it possible that they were actually driving the cases of cancer seen in the soy consumption studies? Remember, the most potent phytoestrogen out there is 8‐prenylnaringenin aka hopein which is found in hops and here’s the kicker—this phytoestrogen has an extremely high affinity for ERα which certainly helps to further explain why alcohol is classed as a carcinogen, but also clarifies why beer is carcinogenic to the breast tissue in particular. What’s more, its concentrations increase exponentially once the constituents in beer are metabolized by gut bacteria! Alcohol is also an aggressive biome disruptor, so could these variables along with a heavy xenoestrogen load be significantly impacting the results of these studies? It is hard to say with any certainty, but should be considered as a factor in phytoestrogen studies in the future.
I’m Soy Confused!—The Actual Issues With Soy
Firstly, the majority of soy is actually grown to feed livestock, not humans; therefore, there is a significant impact on the planet as a result. Only about 6% of soybeans grown worldwide are turned directly into food products for human consumption. 70-75% of the world’s soy ends up as feed for chickens, pigs, cows, and farmed fish.3
Secondly, much of it is genetically modified. According to the FDA, 94% of soy is GMO. It is often found in highly processed forms as opposed to the forms based on traditional preparation methods as well. With respect to the former, there is growing concern over the safety of genetically modified foods and their long-term effects on human health. As for the latter, you cannot make a scientific claim about the benefits of soy and not differentiate between whole food forms vs. highly processed, industrialized forms of soy. When researchers cite the benefits of soy they are not referring to soy meat analogues, but whole food forms.
Thirdly, it is often argued that the soy consumed in East Asia is predominantly fermented and less processed, so if you stay away from processed, industrialized, faux stuff, you’re good to go! However, a fairly recent study found that traditional preparation methods focused on whole food, unprocessed forms like tofu, miso, natto and tempeh, wherein their preparation methods (fermented and unfermented) used longer soaking and cooking times with rinses in between. Remarkably, these extra steps significantly decreased the concentration of isoflavones in these soy foods.
This is very significant, seeing modern East Asians consume approximately 15-50 mg of isoflavones daily, while the study confirms that the isoflavone content in the ancient diet was below 15 mg a day. Notably, the researchers confirmed that commercially made soy milk has the highest concentration of isoflavones in any soy food, often ranging between 90-100%. It appears that soy truly isn’t what it used to be.
Fourthly, it is considered a goitrogenic food because it can interfere with thyroid hormones; thus, can suppress thyroid function. Indeed, the current data suggest that soy is only problematic when there is existing hypothyroidism. That said, because we are bombarded with EDCs, xenoestrogens and other chemicals that have been shown to interfere with thyroid function, it is likely possible that the majority of people are living with subclinical hyperthyroidism which is being exacerbated by soy consumption, coupled with a lack of iodine. Remember, that sufficient iodine is critical for thyroid hormone function and synthesis, which is why soy is often consumed with seaweed or seafood in East Asian populations.
Lastly, it is becoming a more common food allergy. Although some in the “to soy” camp cite this as being rare in the population, it is included in the top eight food allergens list for a reason.
So now that you are armed with more information, what do you do with all of it? Well, the answer is quite simple. On the one hand, you can consume it consciously—especially if you follow a plant-based diet—by embracing true moderation! Because isoflavone content is so much higher today, this is critical. Ironically, we humans love extremes, irrespective of the fact that our life processes are founded on balance, i.e., equilibrium. As a result, we commonly have intense knee-jerk reactions and go buckwild on a lot of things we think are healthy for us. Over-consumption of soy in women is linked to pituitary, endometrial and menstrual cycle impairments in women.2
With all the advances in research and thoughtful food production, there is absolutely no reason that a plant-based diet should be founded primarily on soy when so many awesome options exist out there. So if you are going to do soy, do it right. Stick to organic, non-GMO, fermented whole food forms like mentioned above and stay away from the junky stuff. The fermentation process not only makes it easier to digest, but introduces good bacteria to the gut and reduces its goitrogenic effects. So, be truly moderate and eat it occasionally or 1-2 times per week if you enjoy it. Don’t make it the mainstay plant protein either, because chickpeas, black, lupini, lima, and fava beans are all wonderful options for dense plant-based proteins—especially now that the complete protein is a misnomer.
Smart Soy Foods List
Good for the gut and adds amazing flavour to dishes!
This bold, deep, salty version of soya sauce is a game-changer
Best marinated, then baked or lightly pan-fried. Anyone say tempeh “bacon”?
Cheesy odour and sticky, so an acquired taste, but packed with nutrients and good bugs!
Try and eat it in fermented form if you can!
These young soybeans are pretty fun to eat out of the pod!
There are more and more soy-free choices out there too, so opt for those when you are treating yourself. Remember, the evidence for the benefits of a plant-based diet are based on whole food, not processed, industrialized foodstuff. Aim for homemade burgers made from beet & black bean, walnut & lentil or straight up mushrooms as opposed to a simulated one even if it is soy-free.
Although many don’t consider soy milk as processed, it should be avoided because it is packed to the brim with isoflavones. Don’t forget to eat lots of sea veggies and green, blue-green or brown algae to ensure you are getting sufficient iodine as well! Algae is also packed with omega 3 fatty acids and other critical vitamins, minerals and protein. Algae is definitely in the running for one of the “foods of the future.”
Conversely, you have the option to go soy-free, but now have the facts to also do it right by actually knowing why you are avoiding it. Because it is impossible to know how we metabolize soy without a test, it is best you avoid it if you have trouble digesting it, or if you are concerned about its impacts on your hormones, etc. We are all so unique and diverse, which is why one thing cannot work for everyone. Always do you, but do it with due diligence—always! Don’t forget that if you are trying to avoid soy and follow an animal-rich diet, be sure to switch to organic, grass-fed, wild game/caught options, seeing industrialized livestock are fed soy; thus, an indirect source of isoflavones many do not think about. There is also a growing trend towards soy-free, plant-based diets and it is so easy to do that these days, so go for it!
Lastly, phytoestrogens are highly beneficial overall and may help alleviate the load of xenoestrogens, so consider flax seeds as an alternative to soy. They are phenomenal and the human data collected on lignans to date is very consistent and free of contradictory results commonly seen with soy. The lignans enterodiol and enterolactone have been suggested to exert protective effects on breast cancer, possibly not only by oestrogen receptor‐dependent, but also oestrogen receptor‐independent mechanisms.1
Now, remember, it’s still a phytoestrogen, so don’t overdo it. 1-2 tbsp of ground flax daily is a good range.
1-2 servings a day of these phytoestrogens got you covered!
Rotate them to ensure variety
Where Do We Go From Here?
Now that we have a much clearer picture as to the impact of xenoestrogens and phytoestrogens on our endocrine system, it is time to take the next steps in supporting the body in efficient estrogen detoxification. If you recall from Article 1, the first step is to clean up the diet and ensure you have regulated bowel function to avoid the recycling of estrogens. This is an excellent place to start, but in most cases, extra steps must be taken to balance out hormones.
Did you know that cruciferous aka brassica vegetables like kale, cabbage, brussel sprouts, cauliflower and broccoli assist the body with efficiently detoxifying estrogens? Yep, they are packed with special sulphur containing compounds that break down into indole-3-carbinol and sulforaphane. These highly bio-active compounds assist in flushing excess estrogen out of the body by activating phase II liver detoxification pathways. A general rule of thumb is to lightly steam the majority of your cruciferous veggies. Aim for about 2-3 minutes max on high heat where the veggies become bright green and can be pierced with a fork. Broccoli sprouts have about 100 times more sulforaphane than adult broccoli, so eat this one to two times per week. Be sure to eat iodine-rich foods as well and you should be good to go!
Another supportive measure to consider is calcium D-glucarate. This NHP is pretty remarkable, seeing it has been shown to increase glucuronidation, but also inhibit beta-glucuronidase activity! This is a little miracle in the context of estrogen detoxification for sure. Coincidentally, it is rich in cruciferous veggies, apples and citrus which all impact liver and gut health. That said, be sure to speak to a qualified health practitioner before starting this product.
The above recommendations are excellent starting points to improve overall digestion and hormone health, but if you need some guidance consider working with our registered holistic nutritionist to get your diet cleaned up and gut reset. However, if you are ready to take your health to the next level, consider booking in with one of our team of experts for microbiome mapping and hormone balancing.
*This article is not intended to represent medical advice. Please contact a qualified health practitioner if you want to use any natural health products for specific health conditions. Furthermore, please note that the terms “female” and “male” are strictly used to represent biology and in no way reflect one’s gender identity or expression.
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