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 the health food industry, repeatedly bringing up the same controversy. Is soy healthy? What are the side-effects of consuming soy, if any? Does consuming soy increase estrogen levels?
Widely accepted beliefs abound that soy increases estrogen in humans. To find out if this is fact or fiction, let’s take a deep dive and understand more about estrogen, soy, and the science behind it all. But first: just how is estrogen produced? That’s 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. In women, estrogen is mainly produced in the ovaries, however it’s 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’s 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).
Estrogen balance affects 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 ( non-cancerous tumors), mood issues, fatigue, and both menstrual and premenstrual issues (1).
The endocrine system is a delicate flower. So you can see why increasing estrogen levels could lead to major imbalances and why consumers must know the risks.
Soy products come from the soybean, a legume native to East Asia. It’s used to make a variety of food products, including whole-food forms like edamame, miso and tempeh. Processed soy products include: tofu, milk, vegan cheese, infant formula, meat alternatives, protein powder, flours, sauces, and soy lecithin (a popular emulsifier).
Soy contains all essential amino acids, making it a common staple for vegetarians and vegans (3). In general, some forms of soy are more popular than others; soy milk has long been a popular dairy milk alternative. Many questions surround soy milk and its relationship with human estrogen levels. So does soy milk have estrogen? Although soy milk does not 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 involved pre-menopausal women in Japan and aimed to decipher if soy milk consumption affected 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 estrogen serum levels.
Other studies done examining the relationship between soy and estrogen have focused on a wide array of possible outcomes. Some scientists focused on the positive benefits of soy consumption, whereas others focus on the negative effects of eating soy (6). This is where the controversies arise. Individual studies question the possibility of whether phytoestrogen isoflavones in soy 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. Some studies aim to show how phytoestrogens are breast cancer protective, while others conclude phytoestrogens pose a breast cancer risk (7).
Study of One
Aside from one or two controversial academic articles, most research concludes 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. However, everyone metabolizes things differently. How YOU metabolize estrogen, plus your genetics and current hormone levels all play roles in this debate (as it relates to your specific body).
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? Endocrine disruptors that mimic estrogen. Phytoestrogens can sometimes, in specific situations, weakly mimic estrogen, but xenoestrogens behave differently (some might say badly). 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.
Xenoestrogens are found in industry pollutants, plastic additives, and in pesticides (9). Soy is a crop, commonly sprayed with pesticides. If you consume soy and are also concerned about maintaining the health and balance of your endocrine system, organic is the only way to go.
The issue of pesticides affects most foods. Some get a worse rap than others. Clean all foods sprayed with pesticides, especially fruits and vegetables, thoroughly before consumption. So don’t overlook the serious role the environment plays in this debate.
What You Need to Know About Soy
Just like milk, eggs, and wheat, soy is one of the most common dietary allergies in children and adults. The most common symptoms include itchy skin or hives after consumption. Although unlikely, more severe allergic reactions to soy do exist (10). Read your food labels on all processed foods to ensure that you avoid it if you suffer from allergies.
Do some research, or ask your health care professional if you’re truly concerned about this subject.
If you choose to eat soy, and tolerate it, choose whole, unprocessed, organic soy including tempeh, miso or edamame. Avoid processed soy like milks, yogurts, cheese, soybean oil, soy protein powders, etc. Consider getting a DUTCH hormone test to verify how you’re metabolizing estrogen and to establish baseline levels. If you’ve steered clear from soy until now, we hope this article brought a little clarity.