When it comes to health trends, we’ve seen a few things come and go. Soy has always been one of those foods that finds reinvention in health food industry, repeatedly bringing up the same controversy that surrounds it. Is soy healthy? What are the side-effects of consuming soy, if any? Does consuming soy increase estrogen levels?
There has been a long-standing and widely accepted belief that soy increases estrogen in humans. To find out of this is fact or fiction, it’s important to dive deep and understand more about estrogen, soy, and the science behind it all. But first: just how is estrogen produced? That is the first piece of the puzzle in helping us understand the implications of soy’s alleged effect on estrogen production.
Let’s start with production. Where is estrogen produced? In women, estrogen is mainly produced in the ovaries, however it is also produced in adrenal glands and fat tissues (1). In men, estrogen is produced through an enzymatic process that converts testosterone into estrogen (2).
It is important to have healthy levels of estrogen in both males and females (1,2). In women, estrogen is especially important to menstrual cycling, pregnancy, bone health, cholesterol levels, and more. In men, estrogen regulates reproductive function by aiding in libido and spermatogenesis (4).
It is important to maintain a balance of estrogen, as either too much or too little estrogen can affect both men and women. High estrogen in men can cause enlarged breasts, infertility, and lead to difficulties getting and maintaining erections. High estrogen in women can lead to weight gain, fibroids (tumors which are non-cancerous), mood issues, fatigue, and both menstrual and premenstrual issues (1).
When it comes to the endocrine system, maintaining balance is key. So you can see why the potential of soy increasing estrogen levels could lead to major issues and why consumers need to be aware of the risks – if there are any.
What is soy? Soy products are made from the soybean, which is a legume native to East Asia. Soy is used to make a variety of food products. Some are whole food forms like edamame, miso and tempeh. Soy is also used to make tofu, milk, vegan cheese, infant formula, meat alternatives, protein powder, flours, sauces, and soy lecithin (a popular emulsifier).
Soy also contains all essential amino acids, making it a common staple for individuals who are vegetarian or vegan (3). And in general, some forms of soy are more popular than others. Soy milk itself has long been a popular dairy milk alternative. Soy milk has long been questioned about its relationship with human estrogen levels. Does soy milk have estrogen? Although soy milk does not actually contain estrogen, it does contain phytoestrogens.
In fact, this is true for all soy products. All soy products contain phytoestrogens, specifically a kind called isoflavones. Phytoestrogens are weak estrogen agonists, however some are also antagonists (4). This means that phytoestrogens in general aren’t thought to specifically increase or decrease estrogen, but overall have a balancing effect towards estrogen.
The Relationship Between Soy and Estrogen
What is the relationship between soy milk and estrogen? A 1998 study aimed to answer just that. The study was conducted with premenopausal women in Japan and aimed to decipher if soy milk consumption effected estrogen levels (5). The experimental group was asked to consume 400 ml per day over the period of three menstrual cycles. The authors of the study concluded that between the experimental and control groups, no statistical differences were found regarding their estrogen serum levels.
Other studies done examining the relationship between soy and estrogen have focused on a wide array of possible outcomes. Some scientists have focused on the positive benefits of soy consumption, whereas others focus on the possible negative effects of eating soy (6). This is where the controversy arises. There have been individual studies that question the possibility of phytoestrogen isoflavones in soy to increase estrogen to dangerously high levels in women. More specifically, the authors aim to highlight a relationship between soy, high estrogen, and breast cancer risk.
When it comes to the relationship between soy and estrogen, there is no shortage of information on either side. To get the whole picture, one has to account for the over 2000 soy-related academic articles published every year. While on one side some studies aim to show how phytoestrogens are breast cancer protective, another is published on how breast cancer potentially poses a breast cancer risk (7).
The truth is that aside from one or two controversial academic articles, most research has concluded that phytoestrogens in soy have little to no effect on estrogen either way. That is, it neither provides a positive or negative effect when eaten regularly (8). This is good news to consumers who have already been incorporating soy products in their diet for years. Additionally, you as an individual needs to be considered. How you metabolize estrogen, your genetics and your current hormone levels are important factors. The whole picture of YOU needs to be factored in.
When it comes to foods high in estrogen, soy isn’t inherently a concern. However if anything that could disrupt your endocrine system is of concern to you, it’s important that you have all the information. Although soy is naturally high in phytoestrogens, it can contain xenoestrogens. This is exactly why inside the 131 Method, organic and non-gmo soy is prioritized.
What are xenoestrogens? Xenoestrogens are endocrine disruptors in that they can completely mimic estrogen. Whereas phytoestrogens can sometimes, in specific situations, weakly mimic estrogen, xenoestrogens are different. Think of xenoestrogens as their much stronger, much angrier big sister. In fact, the word “xeno” means “foreign”, meaning xenoestrogens are actually foreign-estrogens (9). These xenoestrogens do a much better job of mimicking estrogen in the body than phytoestrogens do.
Xenoestrogens are found in industry pollutants, plastic additives, and are also commonly found in pesticides (9). As soy is a crop which is commonly sprayed with pesticides, it is important to be aware of this. If you plan on consuming soy and are also concerned about maintaining the health and balance of your endocrine system, pesticides are something to keep an eye out for. If your focus is keeping your hormones in balance, your best option is to buy organic.
Of course, soy isn’t alone here. Other foods that have been sprayed with pesticides, especially fruits and vegetables, should be cleaned effectively before being eaten. So much energy, effort, and emphasis has been put on naturally occurring phytoestrogens and their implications towards estrogen. In actuality, we now understand that the importance lies in looking at the pesticide use in our food industry and how that itself could be effecting us as consumers.
What You Need to Know About Soy
Just like milk, eggs, and wheat, soy is one of the most common dietary allergies to have in both children and adults. The most common symptoms would be itchy skin or hives after consumption. Although unlikely, it is possible to also have a more severe allergic reaction to soy (10). If you are allergic or sensitive to soy, it is important to read your food labels on any of your processed food to ensure that you avoid it.
The best thing you can do if you have a health concern regarding your consumption of any food is to do some peer-reviewed, academically supported research or to ask your health care professional. We’ve provided a breakdown in this article but to summarize, if you choose to eat soy and you tolerate it, choose whole, unprocessed, organic soy including tempeh, miso or edamame. Avoid processed soy products like soy milks, yogurts, cheese, soybean oil, soy protein powders, etc. If you’re super concerned about your estrogen levels with soy intake, consider getting a DUTCH hormone test done to verify how you’re metabolizing estrogen and what your levels are. If you’ve been put off from soy for what you thought it could do, we hope this article cleared things up for you. Bon appetit!