Is Soy Bad for You or a Smart Vegan Food Swap?

by Alena

One of the most common notions people have when thinking of a vegan diet is eating lettuce and large blogs of plain tofu. Doesn’t sound really enticing and luckily also doesn’t represent plant-based eating in the slightest. Along with this naive, yet funny, picture that might come to the uneducated mind is the health concern surrounding tofu & co. With this article, we want to answer questions like “Is soy bad for you” and “Do you have to eat tofu as a vegan”?

Since soy is such a common ingredient in plant-based diets, we need to address the many misconceptions around this food. As a traditional Asian staple food, most know it from dishes like vegetable stir-fries before the veggie burgers have taken over the supermarket shelves.

The health-concerned person might do everything to steer clear of any soy in their diet due to all the myths surrounding this plant-based protein.

In reality, though, these concerns are simply the result of outdated research or misinterpreted results. Unfortunately, many widely circulated beliefs deter people from eating soy and instead, stick to eating high-fat animal products – which isn’t the right way to go about this at all.

So, is soy actually bad for you? We aim to set the record straight here.

What is Soy?

Starting out as the soybean (or Glycine Max), soy is primarily a legume, native to East Asia. It is higher in fat than most beans or lentils, but lower in carbohydrates and an excellent source of plant protein.

In the Okinawan diet, soy is associated with longevity – particularly fermented soy like miso soup and tofu. Soy can be found in many forms, including tofu, tempeh, miso paste or soup, edamame beans, soy yogurt, milk, cheese or ice cream, and veggies burgers and fake meats.

It is this variance in soy and its many forms that have created so much confusion as to whether it is actually healthy or not. The truth is that not all soy is made equal – but we’ll get to that shortly.

The Controversies Around Soy

One of the main concerns around soy involves isoflavones, which much of today’s soy naturally contains. These isoflavones a type of phytoestrogens, which have been described as ‘estrogen mimickers’ in the body and blamed for all kinds of potential consequences.

Especially for men, it is falsely believed that the consumption of phytoestrogens could lead to more feminine characteristics developing in the body – namely gynecomastia (otherwise known as ‘man boobs’)! Potential infertility has also been a worry.

However, there is currently very little (practically none) evidence to support these beliefs. The assumption that plant estrogens (phytoestrogens) perform the same way as mammalian estrogens is just that – an assumption.

Though plant estrogens are structurally similar to mammalian estrogen, they cannot be created by the human endocrine system, and functionally, they are only weakly estrogenic. By occupying our estrogen receptors, phytoestrogens actually lower the estrogen levels in our blood instead of raising it!

In just one case found where a 60-year-old man had developed gynecomastia, he was drinking a whopping ¾ gallon of soy milk a day. After being advised to cut this down, his ‘condition’ was very easily reversed.

Another popular belief is the negative impact on infants who may be fed soy formula from a young age if they’re unable to tolerate cow’s milk formula. But this too was put to rest in a 2004 Italian study, which found no gynecomastia, no altered onset of puberty, no bone structure changes and no hormone fluctuations in infants raised on a soy formula.

For women, it is worried that an increased intake of estrogen could increase their risk of breast cancer, cervical cancer, PCOS and other hormone imbalance-related disorders.

However, this assumption once again ignores the fact that phytoestrogens are different to mammalian estrogens. In fact, it has actually been shown that phytoestrogens can bring benefits to the body by ‘blocking’ actual estrogen and reducing the risk of breast cancer.

It’s also worth noting that soy isn’t the only food that contains phytoestrogens. These types of plant estrogens are also prevalent in coffee, apples, oats, beans, beer, mint, rice, carrots and flax seeds, to name a few. So if avoiding phytoestrogens was the aim…you’d have to cut out a whole lot of foods!

Woman lost in thought

Animal Estrogen vs. Plant Estrogen

Something that many people forget when being wary of phytoestrogens is that animal products contain actual mammalian estrogen, which can have an effect on the body.

As it happens, humans are exposed to natural estrogen from all kinds of ways – such as through drinking water via excretion through women’s urine. But animal product consumption remains by far the highest way. According to, a child’s exposure to estrogens in drinking water is about 150 times lower than exposure from cow’s milk.

Compare this with plant estrogens, which, as we talked about earlier, are naturally occurring plant compounds shown to have a very weak effect on the body.

Soy and the Thyroid

Regular intake of soy has also been linked with thyroid problems in women. Larrian Gillespie, author of The Menopause Diet, warns of ‘estrogen-like’ substances in soy having a dampening effect on the function of the thyroid. It is believed that menopausal women, who are already prone to hypothyroidism, are particularly at risk.

But several studies have since disproved the causal relationship between soy and lowered thyroid function, due to the protective nature of isoflavones. Studies involving rats, pigs and humans demonstrated decreased thyroid peroxidase (an enzyme that helps formulate thyroid hormone) when fed two different isoflavones from soy. However, no overall negative impact on thyroid function was found.

It’s also interesting to note that humans and rats with demonstrated hypothyroidism also happened to iodine depleted – another known causal factor. So adequate iodine intake also plays a part.

Is soy bad for you? Comparison with animal products

Soy Intake and Animal Products

For camps that advise against the consumption of soy (like advocates of the paleo diet), it is likely their preferred source of protein will be meat, fish, and dairy.

However, the irony is that these people are likely consuming soy without even knowing it. According to WWF, only a small portion of soy is consumed directly by humans, with the majority (almost 85%) being crushed and used as feed for poultry, pork, cattle and even farmed fish.

Furthermore, this type of soy is nearly always genetically modified – the type that some health experts warn against eating.

Due to the increase of the Western world’s demand for meat, soy harvesting has increased massively and is now contributing to deforestation and loss of valuable ecosystems in Latin America.

So the answer to avoiding soy or limiting deforestation isn’t to eat less soy…but rather, to eat fewer animal products.

The Deal with Soy Protein Isolate

A large number of studies that have found negative effects of soy have nearly always been done with soy protein isolate – a processed form of soy.

Soy protein isolate (SPI) is made from extracting the fat from soybeans to leave only the protein component. It is commonly used to make veggie burgers and faux meat products, but can also be found in cereals, soups, energy bars, candy and more.

Soy protein isolate isn’t necessarily bad for you, but the way it is made has been a cause of concern for some.

Most SPI is made with a process called hexane extraction. Hexane is a petroleum byproduct of gasoline refining, also used in cleaning agents and as a solvent for glues, inks, and varnishes.

The beans are first soaked in a hexane bath to remove the fat. Then, the ‘defatted’ soy is soaked in ethanol/acidic waters to remove carbohydrates and flavor compounds. The result is a food that is 90% protein.

Hexane, of course, isn’t the only way to make SPI. But it is the cheapest and fastest. Though hexane extraction has been used in food production for over 70 years, there have been a few health risks associated with it in the past.

The CDC classifies hexane as a neurotoxin, with risks ranging from skin irritation and drowsiness to organ damage, lowered fertility and fatality if swallowed (UN GHS system). The FDA currently has no limit on how much hexane residue is allowed in foods (the EU, meanwhile, allows 30 ppm). This all makes it a bit scary to eat soy protein isolate, as we don’t yet fully know the effects of hexane on the body.

Many brands, such as Amy’s Kitchen, have committed to using only hexane-free soy protein isolate in their foods, providing plenty of choice for consumers. And if you want to avoid soy protein isolate entirely, there are plenty of whole, unprocessed versions of soy to enjoy such as miso, tempeh, tofu, edamame, and organic soy milk and yogurt.

Old and fit asian man

The Health Benefits of Soy

Moving onto the more uplifting stuff, there are of course plenty of reasons to eat soy.

Soy contains all the essential amino acids, as well as being a fantastic source of lean protein with fiber and omegas 3 and 6. It is also full of minerals such as calcium, iron, magnesium, manganese, phosphorus, potassium, and vitamins B1, B2, B3, B5, B6, B9, C, and zinc.

Instead of causing cancer, soy has actually long been shown to protect against cancer, due to the highly protective nature of isoflavones. This is especially relevant to the prevention of premenopausal breast cancer, due to the isoflavones’ ability to block estrogen in breast tissue.

And though there continues to be conflicting studies on the topic, one study of breast cancer survivors from China and the US showed a significant association between soy and reduced breast cancer recurrence.

Phytonutrients, found in abundance in soy, are also commended for helping to prevent disease and keep the body working properly. There are more than 25,000 phytonutrients found in plant foods – one of which is phytoestrogens!

Soy is high in isoflavones, a type of phytoestrogen that has been linked with lower risks of endometrial cancer and bone loss in women.

Any ‘anti-nutrients’ in soy are deactivated during cooking and fermentation, and its content of phytic acid has been shown to have anti-cancer effects in animal models for both colon and breast cancer.

People living in countries with more soy in their diets, like Japan, tend to have a lower risk of heart attacks. Experimental research also consistently shows a decrease in total and ‘bad’ LDL cholesterol, with an increase of ‘good’ HDL cholesterol for those who eat more soy.

It’s worth noting that Alzheimer’s disease and other forms of dementia are also less common in Asian populations, where soy is regularly consumed.

Overall, soy is always going to be a healthier substitution for meat, dairy, and eggs. It is always going to be lower in fat, cholesterol, and synthetic or mammalian hormones. Not to mention it’s also a better choice for the animals, and for the environment.

See how it stacks up against animal protein here:

Food face off: soy vs animal protein

How Much Soy Should You Eat?

Different experts have different opinions on how much soy we should be eating, but it all averages out more or less the same message.

Dr. McDougall argues for small amounts of traditional soy foods over large quantities of processed or synthetic soy. For example: ‘soy milk to moisten cereal instead of glassfuls as a beverage; tofu pieces in a stir fry over a soy burger; occasional tofu-based dessert over a daily soy ‘candy’ snack’.

Nutritionist Mark Messina PhD, meanwhile, recommends a daily serving of soy, such as one cup of soy milk or 3 to 4 ounces of tofu.

“If in 20 years researchers have found no benefits to soy, then you’ve lost nothing. If they do find some benefits, then you’ve got a great trade-off”, he says.

Many experts advise to continue eating soy as part of a well-balanced diet but don’t eat it for breakfast, lunch, and dinner.

And many recommend sticking to non-GMO, whole versions of soy, such as miso, edamame, tempeh, organic tofu, organic soy milk and organic soy yogurt. Ginny Messina, RD,  says she still enjoys soy regularly, alongside a variety of other healthful foods.

Is Soy Bad for You?

Let’s sum up the most important findings…

  • Soy can readily be enjoyed as a great source of protein, vitamins, and minerals, as part of a varied diet with plenty of fruits and vegetables.
  • Soy doesn’t need to be eaten in large amounts to get the benefits but getting a little overboard won’t hurt you, either.
  • Whole, unprocessed or fermented forms of soy are best, whilst soy burgers, meats, and cheeses should be enjoyed occasionally as a treat.
  • If you’re worried about soy protein isolate and hexane content, go for organic products that commit to not using hexane extraction.
  • If a vegan woman is worried about thyroid health, she should ensure an adequate amount of iodine in her diet.

Do you enjoy soy regularly or have you been trying to avoid it? Has your feeling towards this legume recently after reading our article? And which soy products do you like the most? Let us know in the comments below.

Alena sitting in a cafe with a bowl of fresh plant-based food and a glass of coffee in front of her

About Alena Handwritten FontAlena Schowalter is a Certified Vegan Nutritionist who has been a vegetarian since childhood and vegan since 2012. Together with her husband, she founded nutriciously in 2015 and has been guiding thousands of people through different transition stages towards a healthy plant-based diet. She’s received training in the fields of nutrition, music therapy and social work. Alena enjoys discussions around vegan ethics, walks through nature and creating new recipes.

27 thoughts on “Is Soy Bad for You or a Smart Vegan Food Swap?”

  1. Just transitioned to vegan a little over 2 weeks ago & I was concerned about soy. This article has really helped me understand what I can have, what I should have & what I should avoid. Thank you – very informative!

    • Hi Kathy,
      so glad we could help! It’s one of the more controversial topics within the vegan community and it was about time to talk about this here.
      Hope you’re doing fantastic!
      Best wishes,

  2. Sometimes it’s hard to discern the truth behind all the information floating around and this article really sums up all the good and eventual bad of the soy consumption. Ultimately, it’s all about the balance and achieving optimal nutritional intake. Any diet can be (un)healthy but there are numerous health benefits of well-balanced vegan diet even though it might take some experimentation to learn what foods your body best responds to.

    • Much easier to be healthy on a plant-based diet than on any other that includes animal products because any added trans fats, cholesterol etc. are worse for your health ;)
      Poor soy has been getting the bad rep for no good reason but financial interest. Let’s bring it back to the table!

  3. I’m so glad I came across this article! With so much sensational information and conflicting myths out there, this piece summarized all the facts from both side in a clear, concise way. I had no idea about the SPI, for example. Very good to know. Thanks for writing this! I started a plant-based Diet about a month ago and I’m relieved I can include organic soy in my meals without worry.

  4. Hey, this is my second year on being vegan now, yay! I would like to ask: Is it true that if women have too much soy it could affect their menstrual cycle? I love having Light Vanilla Soy Milk with my cereal because it gives it a pop of flavor!

    • Hi Isabella,
      soy is a very healthy and great addition to your diet (except if you’re allergic to it). As explained in the article, soy (and other foods containing phytoestrogens) have a positive effect on your hormones… here’s a quote from Dr. Greger: “Soy seems to lower breast cancer risk, an antiestrogenic effect, but can also help reduce menopausal hot-flash symptoms, a proestrogenic effect. So, by eating soy, you may be able to enjoy the best of both worlds.” source:
      Bottom line: probably no need to change :) Enjoy the Silk!

  5. This is factually inaccurate for a number of reasons which is very typical for the vegan community. Constantly spreading false truths based on their feelings towards the earth. Your body hates soy but lets leave that alone for a moment. What really makes me laugh is at the end of the article where it says soy is good for you AND the environment. The earth HATES soy. This genetically modified earth killer is terrible for the ecosystem. Bad for soil health, horrible use of agricultural land, needs tons of pesticides and artificial fertilizers to survive, not to mention how much of it we would need to grow if we all went vegan. Say bye bye to natural habitat in favour of USELESS SOY FIELDS!!! Im an ecologist, a farmer, and have been involved with human health my whole life. To understand soy and veganism as a whole, you need to understand ecology, agriculture, and health. Vegans never know about those things. There are far more pieces to the puzzle that vegans dont consider. Uneducated article.

    • I think I cited enough credible sources in the article which you can follow instead of just having to listen to me :)
      No need for vegans to eat soy. Most soy is being fed to livestock. Soy for human consumption is most always organic, non-GMO. Eating animals is far worse in every aspect.

    • Hmm, John, not that I’m a vegan myself, but could you list some research that supports your claims as the author has? Like you make these claims which may have some merit but don’t do anything to back it up, thus it offers little validity in its current state.

  6. I find this very confusing and will research further but wonder if the old women in China are so much healthier than ours because they do Qi Gong or Tai Chi every morning instead of being given free television licences!

  7. Hi,
    I came here because of SOY Milk but didn’t see if that is advised as safe or not.
    If it is, what is the best SOY Milk to purchase (Brand etc)

    Thanks a lot. Great site by the way!

    • Hey Marcos,
      thanks for stopping by. I’d say the best soy milk is made from whole soybeans instead of concentrate and is free from added sugar or tons of preservatives. The soy milk we purchase in Germany only has 2 ingredients: soybeans and water :)
      Hope this helps!

  8. This truly helped. The first transition was to a vegetarian when my gallbladder was removed I found that it was less trips to the bathroom, less cramps, and overall felt more energetic. However I did have a few cheats. I love turkey and cheese and haven’t found good alternatives. When I found that I am infertile due to my weight I decided all the way vegan it was with a great $10 membership to planet fitness. So I’m super confused on what to eat and what not to eat I tried Silk dairy-free yogurt but got a little worried when I seen Soy. So this article was great to find.

    • Hi Quinn,
      thanks for sharing! Happy that we could shed some light on this topic. Feel free to join our free course (in the menu) or read more free articles on transitioning to and eating a healthy, cheap vegan diet :)
      All my best,

  9. I was just watching a video by gersons and she said that everyone should avoid soy completely. Reason being that there isn’t anything to absorb. Basically, she’s saying it causes malabsorption. The thing is, I’m vegan and I eat soy every now and then as curry or I might make black bean tofu. (forgot to add that I consume Soy in the form of Tofu only). I’m glad you posted this article, I’ve been watching videos on but I’m still not 100% satisfied with everything I’ve read so far. Thanks for this informative article!

    • Hey Christina,
      thanks for sharing. I truly get it, nobody seems to agree on nutrition topics. If I were you, I’d wonder which proper studies have caused Gerson to say these things about soy or whether it’s just a theory. Nice that you’ve been watching Dr. Greger, keep educating yourself so you can come to a conclusion :)
      Best wishes,

    • good question! Pretty sure that this just means soy milk but maybe you can ask the producer in that case. Sometimes, it’s also labeled as vegan or dairy-free :)

  10. Thank you for this article!
    Although I am still unsure in regards to tofu and meet replacements that tend to be made with Rehydrated Soya Protein, are these supposed to be eaten as a treat as mentioned on the articule or are they safe to have on several meals a week?

    • Hey Rita, thanks for your comment! Not sure what you mean by rehydrated soya protein but I imagine it being something like textured veggie protein which you can use to replicate bolognese sauce, for example.
      The question I would ask is this: what does it replace and how much of the original food has been taken away? If you still have the fiber, minerals etc. from the soybean then it seems like a healthy choice. If you eat it instead of meat, it’s a really, really healthy choice :) if you eat it instead of broccoli, might be less healthy but definitely still has a place in a healthy diet. Sure, I’d eat it several times per week personally.
      Hope this helps!

  11. Hi, thank you for the article it helps me a lot!!!!!!!!!!!!!!!!!!!!!!!!!!
    I was vegetarian sinds I was 20 years old (23 years ago) in 2011 I went to vegan. I was always afraid of all the things I heared about soy. But it is so difficult for me to get all the protiens from other vegtebles because I have intestinal problems.
    I’m now 43 and trying to concieve (I know that its old…) so I’m so afraid of doing somthing wrong. My clock is tikking by the hour. I know I will become pregnant. I really belive that. But I have so many worries about a lot of soy during pregnancy. I know use a organic soy protein powder every day so I get extra protiens. Is it ok to use it every day? And also during pregancy? I drink it whith soy milk because I like the taste of soy milk. I dont eat a lot of meat replacments or tofu. Only a few times a week.
    I hope you can give me an answer.
    I’m from Holland and here all the nutriests speak so bad about soy. But what can I eat? For me it is hard with my intestinal problems.
    Sorry for this long writing.
    The question: can I take a organic soy protein powder every day, and also during pregancy? And can I give it to a baby when its 1 year old.

    Sorry again for the long writing.

    Thank you for all your help!!!

  12. Thank you for this article and the clarification on soy. I truly enjoyed reading it. For a long time I had been afraid to eat to many soy based products. I was diagnosed with breast cancer in 2004 at the age of 31. I went through all the necessary treatments and surgeries for almost a year before I went into remission.
    In 2007 I started working for an Indian doctor who drank a lot of soy milk and she had me hooked on it! I was drinking a lot of it for years. Then in 2013 I hadn’t been feeling well and was sent for testing only to find out that my cancer had returned and metastasized to my thoracic area and I was devastated! I had heard negative things about soy increasing the risk of breast cancer and had blamed myself for years. However, my middle daughter, who has been vegan now for 6 years, had told me that she read differently and said that it was safe. My cancer continues to spread and then improve and spread again so I decided as of January 19th of this year to jump right in and become vegan, with my daughters persistence lol. My tumor markers have come down every month and has me looking forward to a longer future.
    However, my recent PET Scan shows more Mets so now I’m looking to go completely oil free, whole food Plant based and I am excited for this journey.
    So again thank you for this article because I was ready to go back to my old eating habits.


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