All You Need to Know About Endometriosis and Soy
Symptom management strategies for endometriosis vary from person to person but the use of diet and lifestyle strategies for symptom relief are gaining popularity, as certain nutrients and dietary patterns may reduce endometriosis risk and help alleviate symptoms. One of these strategies you may be aware of and many might try is either including or excluding soy foods. But what does science say about endometriosis and soy?
Soy and endometriosis has to be one of the most debated nutrition topics when it comes to the so-called “endo diet”. If you have looked into it yourself then you will have seen that there's so much conflicting information online – it can be tough to figure out what's true! In this blog post we’ll help you navigate fact from fiction and uncover the role of soy and soy products like soy milk and endometriosis and how you can practically incorporate it into your diet in the right amounts to support you in your endometriosis journey.
What Are Soy Foods?
To put it simply, they are foods made from soybeans, a type of legume widely consumed in Chinese and Japanese diets. This includes foods like edamame, soy-based drinks, tofu, tempeh, miso, and soy sauce.
Soy has been a dietary staple in Asia for centuries and is now widely consumed globally, yet opinions on its health benefits remain divided. This is partly due to the sheer volume of research, making it challenging for health experts to provide clear guidance (1).
In the UK, soy foods, also sometimes called "soya," have gained popularity, particularly as plant-based alternatives to dairy, and can be used to make plain or flavoured desserts, yoghurts, burgers, or mince substitutes (what you would find in many plant-based burgers) (2).
Soy And General Health
Over the past 20-30 years, around 2,000 studies per year have explored soy's health impacts. Some of the health benefits associated with eating soy foods include (3):
Cancer prevention
Alleviation of menopause symptoms
Memory enhancement
Many of these benefits have been linked to the phytoestrogens in soy, especially isoflavones.
Soy And Phytoestrogens
Phytoestrogens are plant compounds (also commonly called polyphenols), found abundantly in soybeans and soy products like tofu. As they resemble the human hormone oestrogen, it is thought that they might act like oestrogen in the body, which is why soy is often called an endocrine (hormone) disruptor and gets a bad rep when it comes to hormonal conditions, like endometriosis. The most studied phytoestrogens are isoflavones and coumestans with soy containing the largest concentration of isoflavones.
Some studies suggest phytoestrogens may bring health benefits such as improving heart health and helping to alleviate hot flashes in menopause. However overall the evidence remains mixed (4) with some praising soy's benefits and others expressing concerns (4). So the potential side effects and long-term hormonal impacts of phytoestrogens, especially their links to hormone-related cancers and menopausal symptoms, are still debated (5).
Promisingly though, a recent comprehensive review of all the evidence carried out so far, suggests that soy and isoflavones are likely safe and should not be classified as endocrine disruptors (6).
Soy Protein and Health
Soy's health effects are complex and multifaceted. Soy protein is often touted as a health food, with research suggesting benefits for heart health, cholesterol levels, and muscle mass (1). A recent systematic review found that including soy isoflavones in the diet positively affected arterial stiffness which is a risk factor for cardiovascular disease thus supporting soy protein's role in heart-healthy diets (6). Despite debates over its processing and health claims, soy protein may remain a significant component of heart-healthy diets.
Beyond tofu, various fermented soy products contribute to its intricate role in overall health, which remains another area of ongoing research.
Is Soy Bad For Endometriosis?
Soy and its phytoestrogens were once feared to worsen endometriosis due to their oestrogen-like effects, potentially stimulating growth of endometriosis lesions (7).
However, recent research has shown that phytoestrogens have variable effects on hormone regulation. They can mimic oestrogen activity when levels are low and as anti-oestrogens when levels are high, effectively changing hormone activity and potentially reducing overall oestrogen availability depending on oestrogen levels. This may alleviate endometriosis symptoms in some individuals (8).
Studies in high soy-consuming countries like Japan suggest a correlation between increased soy intake and reduced risk of endometriosis progression (9). Although further research is needed, these findings suggest that soy and its phytoestrogens might help manage endometriosis symptoms, offering potential relief for those affected by this condition.
How Much Soy Can I Include In My Diet?
Health organisations provide limited guidance on soy intake with recommendations varying depending on the specific population and clinical condition, from 25g soy protein per day in the USA to 40g soy daily in China (10).
Research suggests that beneficial health effects may be seen with 50-160 mg of isoflavones per day (11). However, these benefits are often observed in studies using multiple isoflavone types, and the direct relationship between isoflavone intake and benefits is unclear.
A reasonable recommendation is to consume 15-25 grams of soy protein and 50-100 mg of isoflavones daily (10). The soy protein and isoflavone content of commonly eaten soy products can be seen below to help you:
100g tofu: 17g protein, 58g isoflavones
100g tempeh: 21g protein, 75g isoflavones
200g soy yoghurt: 6.5g protein, 23g isoflavones
200mls soy milk: 6g protein, 22g isoflavones
100g edamame beans: 14g protein, 49g isoflavones
50g dried soya beans: 20g protein, 70g isoflavones
While consuming more soy is unlikely to be harmful, there is little evidence that higher amounts offer additional benefits.
Soy can be a valuable part of your diet, particularly for its potential health benefits in specific conditions. However it might not suit everyone, and that's okay. Eating protein foods from a variety of sources in your diet is also advisable, so aim to include a mixture of soy, beans and pulses, oily fish, lean meats and nuts and seeds, depending on your dietary preferences..
Meal Ideas for Incorporating Soy Into Your Diet
Incorporating soy into your diet is easy and versatile. Soybeans are rich in protein, healthy fats, fibre, and essential nutrients. They can be a great addition to meals, especially if you're trying to reduce your red meat or refined carbohydrate intake. However, if your diet is already balanced, adding soy might not significantly change your overall health or improve endometriosis symptoms.
Here are some popular soy foods and ways to enjoy them:
Get creative with soy! There are countless recipes online, so don't hesitate to try new dishes and find what you enjoy the most.
Edamame: These young, green soy pods can be boiled, steamed, or microwaved and enjoyed with a sprinkle of salt as a snack or side dish.
Mature Soybeans: Available dried or canned, they can be used in main dishes like chilli or added to salads for extra protein and fibre.
Soy Milk: Made from water and ground soybeans, soy milk is a popular alternative to cow's milk and can be used in cereals, smoothies, and baked goods.
Tempeh: This fermented and cooked soybean product is great for marinating and grilling. It can also be sliced or crumbled into stir-fries, salads, sandwiches, and stews.
Tofu: Made from curdled soy milk, tofu is versatile and comes in various textures like silken, firm, and extra firm. It can be diced into stir-fries, salads, or entrees, baked, or scrambled with veggies and spices for a protein-rich breakfast.
Take Away Message
While the debate around soy and its effects on health, particularly in conditions like endometriosis, continue to swirl, recent insights shed light on its potential benefits. Contrary to previous concerns, soy and its phytoestrogens may not worsen endometriosis but rather offer relief by modulating hormone activity. However, the optimal amount of soy to consume still remains a bit of a puzzle. While soy may not be a one-size-fits-all solution, it's worth exploring for its potential health benefits, especially in managing conditions like endometriosis.
Whether it's enjoying edamame as a snack, adding tofu to stir-fries, or experimenting with soy milk in smoothies, the options are endless. Remember to embrace your inner chef, listen to your body, and find what works best for you!
If you're vegetarian, vegan, or want to simply add plant protein sources such as soy into your diet, consult a dietitian to find ways to meet your nutritional needs. You can book a free discovery call with Claire, a specialist women’s health dietitian to discuss this further.
References
Isoflavonoids — an overview of their biological activities and potential health benefits
The health effects of soy: A reference guide for health professionals
Phytoestrogens for the Management of Endometriosis: Findings and Issues
Effect of soy isoflavones on endometriosis: interaction with estrogen receptor 2 gene polymorphism