If you suffer from PCOS (Polycystic Ovarian Syndrome) you may be familiar with the conflicting information about the effects of soy on this condition. Does soy really make PCOS worse or are there any benefits to it? Should you avoid it completely or are any forms of soy better than others?
Since there are so many opinions and controversy surrounding this topic I’ve decided to break it down for you in this evidence-based article. Hopefully, you’ll be able to find all your answers about soy in relation to PCOS and make an informed decision on whether to include it in your diet.
If you’d like to learn more about the role of nutrition in the management of PCOS, make sure to check out my easy-to-follow diet guide here: ‘The Best PCOS Diet For PCOS (Ultimate Guide)’.
What is soy?
Soy is a popular type of legume that comes from a soybean plant. Soybeans can be eaten in many different forms and it is a staple ingredient in many traditional cuisines (especially Asian). Depending on the processing method, you’ll be able to find:
- unprocessed soy (whole soybeans, edamame beans, soybean nuts),
- fermented soy (tempeh, miso, soy sauce, natto, soy yogurt),
- minimally processed soy (soy milk, tofu)
- ultra-processed soy (fake meat, soybean oil, soy isolate)
While the effects of soy on your health can largely differ based on the type of soy you decide to eat (the less processed the better), there appear to be some benefits associated with this nutrient-rich legume for women with PCOS.
Benefits of soy for PCOS:
- Nutrient content
- Improved insulin resistance
- Reduced androgens
- Improved fertility
- Cardiovascular health support
- Reduced inflammation
✓ Nutrient content
First of all, whole soybeans are a great source of multiple essential nutrients and beneficial phytonutrients. Like most legumes, soybeans are high in protein and fiber but in contrast to other beans, soy is actually one of the rare plant sources of complete protein (containing all 9 essential amino acids).
That’s why soy is particularly popular among vegetarians, vegans and plant-based eaters as a good source of protein. Soy is also rich in vitamins, minerals, omega-3 fatty acids and antioxidants while being low in sugars and saturated fat.
1 cup of cooked edamame beans contains:
| 1 cup (155g) | amount (% of daily value) |
|---|---|
| Calories | 189kcal |
| Protein | 18g |
| Carbohydrates | 15g |
| Fiber | 8g |
| Fat | 8g |
| Omega-3 | 560mg |
| Sodium | 9.3mg |
| Potassium | 676mg (19%) |
| Folate | 482mcg (121%) |
| Magnesium | 99.2g (25%) |
| Iron | 3.5mg (20%) |
| Vitamin C | 9.5mg (16%) |
| Vitamin B6 | 0.2mg (8%) |
| Calcium | 97.6mg (10%) |
| Vitamin E | 1.1mg (5%) |
| Vitamin K | 41.4mg (52%) |
| Thiamin | 0.3mg (21%) |
| Riboflavin | 0.2mg (14%) |
| Niacin | 1.4mg (7%) |
| Pantothenic acid | 0.6mg (6%) |
| Phosphorus | 262mg (26%) |
| Zinc | 2.1mg (14%) |
| Manganese | 1.6mg (79%) |
| Copper | 0.5mg (27%) |
Including high-quality soy products in your diet could therefore be an effective way to help meet your nutrient requirements which is particularly important for women with PCOS. It’s been shown that certain nutrients (such as magnesium, zinc, B vitamins) play a major role in the management of PCOS and that their sufficient intake may help improve this condition.
✓ Improved insulin resistance
Insulin resistance is a hallmark feature of PCOS that appears to be responsible for hyperandrogenism (high levels of androgens) in most women with this condition. You can find more details about this pathway in my previous article ‘PCOS Insulin Resistance Explained & How To Reverse It’.
Since high levels of insulin in the blood (due to insulin resistance) can trigger your ovaries to produce excessive levels of androgens (the ‘male’ hormones) it is particularly important for women with PCOS to focus on stabilizing their blood sugar levels and prevent hyperinsulinemia.
Dietary and lifestyle changes are one of the best ways to do so and you can learn more about it here: ‘How To Treat PCOS Naturally (Science-Based Guidelines)‘.
Interestingly, several studies have also shown soy isoflavones to be effective in improving multiple biological markers of insulin resistance in women with PCOS. Soy appears to not only lower the levels of circulating insulin in the blood but also improve insulin sensitivity (how your cells respond to insulin).
While the research is still in its infancy, some suggest that soy could have some serious therapeutic effects for women with PCOS.
✓ Reduced androgens
It is clear that high levels of androgens in the blood drive most of the common ‘male-like’ symptoms of PCOS such as acne, hair loss, hirsutism or irregular periods. Reducing androgen levels is therefore one of the most effective ways to alleviate those symptoms and restore hormone balance in women with PCOS.
The good news is that soy has been shown to significantly lower testosterone levels in multiple studies involving women suffering from PCOS. The anti-androgenic effects of soy are believed to be the result of improved insulin metabolism and increased levels of SHBG (sex hormone-binding globulin) in the blood.
SHBG (which is typically decreased in women with PCOS) is a type of protein responsible for binding to sex hormones (such as testosterone) and eliminating excessive levels of androgens from the body. For this reason, increasing the levels of SHBG in the body also helps drastically lower androgens. And soy may be an effective way to do that.
✓ Improved fertility
PCOS is considered to be the leading cause of female infertility due to hormone imbalances and lack of ovulation typical for this condition. However, it doesn’t mean that women with PCOS cannot successfully conceive and experience a healthy pregnancy.
In fact, most of them can get pregnant naturally once their hormonal balance and ovulation cycle are restored. Fortunately, there are many ways in which you can support your fertility such as improving your metabolic health, reducing insulin resistance and lowering androgens.
As I’ve already discussed above, soy appears to be effective in all of those areas and therefore could lead to improved ovulation and overall fertility. Additionally, the intake of soy has been associated with increased rates of pregnancy, live births and fertilization rates in several other studies.
One large study also suggests that increased intake of soy-based proteins (edamame, tofu) may help lower the risk of infertility in ovulatory disorders (such as PCOS). However, there is a lack of research investigating the effects of soy on fertility in women with PCOS specifically.
✓ Cardiovascular health support
Another great benefit of soy for women with PCOS is its ability to improve heart health and support the cardiovascular system. The data shows that women with PCOS are at increased risk of heart disease due to their metabolic and hormonal abnormalities, but soy intake has been associated with beneficial effects on cardiometabolic markers.
A few studies involving women with PCOS have shown significant reduction in total and LDL (the ‘bad’) cholesterol, blood triglycerides and blood pressure after the consumption of soy isoflavones. It is therefore suggested that soy may be particularly beneficial as a heart health support for those individuals.
✓ Reduced inflammation
Soy is a rich source of multiple phytonutrients such as isoflavones, antioxidants and other anti-inflammatory compounds. As a result, the consumption of soy may help reduce inflammation and oxidative stress in the body as it’s been demonstrated in multiple studies.
This is crucial for women with PCOS as chronic inflammation and high levels of oxidative stress are some of the main contributors to the development and progression of the syndrome. The good news is that several studies (involving women with PCOS) have shown a significant reduction in inflammatory markers and oxidative stress levels as well as an increase in antioxidant levels (such as glutathione).
In addition, soy also appears to be effective in protecting against the endocrine disruptor BPA which is typically high in women with PCOS. One study has demonstrated that women with increased intake of soy had a significantly lower concentration of BPA in the blood (and increased pregnancy rates) in comparison to those who did not eat soy. However, more research is required.
Things to consider:
- Quality
- Allergies
- Phytoestrogens
• Quality
Despite the many benefits associated with the consumption of soy for PCOS, there are a few things you should always keep in mind if you want to gain the most benefits. First of all, not all soy is created equal and the quality really matters.
One of the issues of soy is that due to its mass production (mostly for animal feed) a large proportion of it is genetically modified and grown using harmful chemicals. For this reason, I highly recommend always choosing non-GMO and organic soy products as they tend to be still very affordable.
I also suggest you opt for more unprocessed, fermented or minimally processed soy products (such as soybeans, edamame, tempeh, tofu, natto, miso, soy milk) and limit your consumption of ultra-processed soy (such as textured soy protein, soybean oil, meat alternative, soy isolate).
Here are some high-quality soy products:
- YUHO Organic Shiro White Miso Paste (best for soups/sauces)
- Morinaga Organic Silken Tofu (best for baking/desserts)
- House Foods Organic Firm Tofu (best for cooking)
- Lightlife Organic Tempeh (best taste)
- NYrture Organic Natto (best as a delicacy)
- Eden Organic Soymilk (best milk alternative)
- Explore Cuisine Organic Edamame Spaghetti (best pasta alternative)
- Be Still Farms Organic Soybeans (best natural form)
• Allergies
Another thing to keep in mind is that soy is a very common allergen that a large proportion of people can’t tolerate. Always consider your own allergies, food sensitivities and body responses to soy (a food diary may be a good start) and eliminate it from your diet if it triggers you.
Soy may also cause some digestive issues in certain people due to its high content of fermentable carbohydrates (FODMAPs). Therefore, if you suffer from IBS you may want to minimize your consumption of soy or try different forms of it (eg. fermented soy).
• Phytoestrogens
The reason why soy is believed to be problematic for some individuals is because it contains high amounts of isoflavones (phytoestrogens). Those naturally occurring plant compounds are oftentimes compared to human estrogen although there are differences in their chemical structures.
Nonetheless, it is suggested that phytoestrogens (plant estrogens) may mimic the action of human estrogen once in the body and therefore cause hormone imbalances. While this claim is not sufficiently supported by science as phytoestrogens are much weaker and won’t have the same effect as estrogen, it could still affect estrogen receptors.
For this reason, consuming high amounts of soy (or other phytoestrogen-rich sources such as flaxseeds) is generally not recommended for individuals suffering from estrogen dominance, thyroid problems and pregnant/breastfeeding women.
However, a moderate intake of high-quality soy products is not likely to cause any harm and according to research may actually improve hormonal function in women with PCOS.
Best types of soy for PCOS:
- soybeans
- edamame beans
- soy nuts
- tempeh
- tofu
- miso
- soy sauce
- natto
- soy milk
- soy yogurt
Worst types of soy for PCOS:
- soybean oil
- textured soy protein (TSP)
- soy protein isolate
- fake meat/ meat alternative
- energy bars & cereals
Is soy good for PCOS?
According to research, soy appears to be good for PCOS as it may help reduce insulin resistance, lower androgens, improve fertility and decrease inflammation. However, the effects of soy on PCOS may differ between individuals based on their unique hormonal profile and the type of soy consumed.
Can soy make PCOS worse?
There is no sufficient evidence showing that the consumption of soy makes PCOS worse. In fact, the research suggests that soy might have beneficial effects on hormonal and metabolic health in women with PCOS. However, soy is a common allergen that may be poorly tolerated by many individuals.
Is tofu good for PCOS?
In general, tofu can be considered good for women with PCOS as it’s only a minimally processed type of soy high in protein, essential nutrients and antioxidant compounds. However, it is best to opt for plain unflavored tofu that is GMO-free and organically grown to gain the most benefits.
Is soy sauce good for PCOS?
Soy sauce can be generally considered good for PCOS as it’s a type of fermented soy that is associated with many health benefits. However, since soy sauces are typically high in sodium and other food additives (wheat, colors, flavors) it is important to choose high-quality soy sauce products.
Pro tips:
- Buy organic – when buying any type of soy product try to look for those certified as organic and GMO-free to minimize your exposure to harmful pesticides and industrial chemicals that may cause disturbances in hormones
- Track your progress – get tested and keep a track of your progress, with enough data you’re more likely to see what dietary strategies work for you best and it also helps you stay motivated, you can find some useful tools here ‘TOP 5 Smart Devices To Monitor & Manage PCOS‘
- Stir fry – try adding some cubed tofu, tempeh or soybeans into your stir fry, it’s an easy and delicious way to increase your meal protein content, especially if you’re in a rush or out of other protein sources (it also works in soups, salads and other meals)
- Dairy alternative – soy can be used as a great dairy alternative (to make milk, yogurt, cheese) as it’s high in complete protein and it has a relatively neutral taste, you can find more information here: ‘What Type Of Milk Is Best For PCOS? (The Ultimate Guide)‘
- Snack – edamame beans or soy nuts are a perfect high-protein snack that will keep you satiated and prevent further sugar cravings, try baking (or air-frying) edamame beans and adding some salt on top (it tastes like popcorn to me)
Read more: ‘PCOS Cravings: How To Reduce Appetite & Excessive Hunger‘ - Desserts – you can also use soy (especially tofu, soy milk or soy yogurt) for baking and making sweet desserts, silken tofu is a particularly great dairy-free alternative to make vegan cheesecakes, creams, and puddings
Resources:
- Chavarro, J. E., Rich-Edwards, J. W., Rosner, B. A., & Willett, W. C. (2007). Diet and lifestyle in the prevention of ovulatory disorder infertility. Obstetrics and gynecology, 110(5), 1050–1058. https://doi.org/10.1097/01.AOG.0000287293.25465.e1
- Chavarro, J. E., Mínguez-Alarcón, L., Chiu, Y. H., Gaskins, A. J., Souter, I., Williams, P. L., … & EARTH Study Team. (2016). Soy intake modifies the relation between urinary bisphenol A concentrations and pregnancy outcomes among women undergoing assisted reproduction. The Journal of Clinical Endocrinology & Metabolism, 101(3), 1082-1090. https://doi.org/10.1210/jc.2015-3473
- Dennett, C. C., & Simon, J. (2015). The role of polycystic ovary syndrome in reproductive and metabolic health: overview and approaches for treatment. Diabetes spectrum : a publication of the American Diabetes Association, 28(2), 116–120. https://doi.org/10.2337/diaspect.28.2.116
- Jamilian, M., & Asemi, Z. (2016). The effects of soy isoflavones on metabolic status of patients with polycystic ovary syndrome. The Journal of Clinical Endocrinology & Metabolism, 101(9), 3386-3394. https://doi.org/10.1210/jc.2016-1762
- Khani, B., Mehrabian, F., Khalesi, E., & Eshraghi, A. (2011). Effect of soy phytoestrogen on metabolic and hormonal disturbance of women with polycystic ovary syndrome. Journal of research in medical sciences : the official journal of Isfahan University of Medical Sciences, 16(3), 297–302. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3214337/
- Ma, X., Li, X., Ma, L., Chen, Y., & He, S. (2021). Soy isoflavones alleviate polycystic ovary syndrome in rats by regulating NF- κB signaling pathway. Bioengineered, 12(1), 7215–7223. https://doi.org/10.1080/21655979.2021.1979864
- Messina, M. S. (2019). Health Update: Evaluation of the Clinical and Epidemiologic Literature. Nutrients 8. 8(12):754. doi:10.3390/nu8120754
- Moghetti, P., & Tosi, F. (2021). Insulin resistance and PCOS: chicken or egg?. Journal of endocrinological investigation, 44(2), 233–244. https://doi.org/10.1007/s40618-020-01351-0
- Osibogun, O., Ogunmoroti, O., & Michos, E. D. (2020). Polycystic ovary syndrome and cardiometabolic risk: Opportunities for cardiovascular disease prevention. Trends in cardiovascular medicine, 30(7), 399–404. https://doi.org/10.1016/j.tcm.2019.08.010
- Rajan, R. K., M, S. S., & Balaji, B. (2017). Soy isoflavones exert beneficial effects on letrozole-induced rat polycystic ovary syndrome (PCOS) model through anti-androgenic mechanism. Pharmaceutical biology, 55(1), 242–251. https://doi.org/10.1080/13880209.2016.1258425
- Romualdi, D., Costantini, B., Campagna, G., Lanzone, A., & Guido, M. (2008). Is there a role for soy isoflavones in the therapeutic approach to polycystic ovary syndrome? Results from a pilot study. Fertility and sterility, 90(5), 1826–1833. https://doi.org/10.1016/j.fertnstert.2007.09.020
- Shahin, A. Y., Ismail, A. M., Zahran, K. M., & Makhlouf, A. M. (2008). Adding phytoestrogens to clomiphene induction in unexplained infertility patients–a randomized trial. Reproductive biomedicine online, 16(4), 580-588. https://doi.org/10.1016/S1472-6483(10)60465-8
- Unfer, V., Casini, M. L., Gerli, S., Costabile, L., Mignosa, M., & Di Renzo, G. C. (2004). Phytoestrogens may improve the pregnancy rate in in vitro fertilization-embryo transfer cycles: a prospective, controlled, randomized trial. Fertility and sterility, 82(6), 1509–1513. https://doi.org/10.1016/j.fertnstert.2004.07.934