Is Soy Safe?

Alexis Joseph, MS, RD, LD
by Alexis Joseph, MS, RD, LD
Share it:
Is Soy Safe?

A great source of complete plant protein, soy has been a staple in Asian diets for thousands of years. There’s no debating it — soy can be found in pretty much anything these days. And we’re not talking about tofu and soy sauce here. From protein bars and veggie burgers to chicken noodle soup, soy has become ubiquitous in the food system in one form or another. It’s inexpensive, packed with protein and relatively tasteless. Additionally, some soy foods are made with calcium sulfate, which makes them good sources of calcium, too.

However, some fear that these foods may not be safe because soy contains certain estrogenlike compounds — and high levels of estrogen have been linked to increased breast cancer risk. Let’s dig a little deeper to find out whether or not this is true.

Understanding the Soy-Cancer Connection
The question around the safety of soy stems from isoflavones, a group of estrogenlike compounds made by certain plants that can mimic the actions of estrogen. While high levels of estrogen have been associated with an increased breast cancer risk, interestingly enough soy actually seems to protect against breast cancer, prostate cancer and even heart disease in human studies. This cancer-fighting effect likely comes in part from other phytochemicals in soy that reduce inflammation and prevent activation of proteins that promote cell growth commonly seen with certain cancers. As an added bonus for women, soy may also provide relief from menopausal symptoms, though the jury is still out on whether or not soy protects against osteoporosis.

Since Americans don’t eat large quantities of soy, it’s not easy to conduct observational studies comparing how various intakes link to cancer risk. In Asia, where soy is a staple and women consume 1–2 servings per day, population studies link regular consumption with lower breast cancer risk. (One serving being equivalent to 1/3 cup tofu, 1 cup soy milk, 1/2 cup edamame or 1 ounce soy nuts.)

What about cancer survivors? According to the American Institute for Cancer Research, consuming moderate amounts of soy does not increase a woman’s risk for poorer outcomes. In fact, consuming moderate amounts of soy appears to reduce recurrence and increase survival rates. The same goes for prostate cancer survivors — trials show that consuming soy food may be beneficial while none demonstrated harm.

Is there more to this debate? Yes. Opponents of soy consumption question its impact on male fertility, its anti-nutrients (Think: phytic acid, lignans and phytoestrogens — compounds that can interfere with absorption of certain minerals), and the long-term health effects of consuming modern forms of highly processed soy. Regarding fertility, some studies show no impact of soy consumption on male fertility and reproductive hormones while some show a negative effect. If you eat a varied diet of nutrient-rich whole foods, anti-nutrients shouldn’t be a concern; however, soaking, fermenting and heating soy may help mitigate the impact anti-nutrients may have on absorption.

The Takeaway
Our take? The impressive anti-cancer benefits of soy outweigh the possible concerns. To maximize the benefits, consume moderate amounts of soy in whole-food (minimally processed) forms. More research is needed to know the long-term health effects of consuming the highly processed versions of soy foods lining the shelves today. Lastly, be wary of anti-soy studies that rely heavily on animal rather than human research studies.

To enjoy your tofu without worry, here are a few tips to get the most nutritional benefit from soy foods in your diet.

  • Stick to whole soy foods. Getting 1–2 servings of tofu, tempeh, edamame, miso and soymilk daily can be wonderful additions to a healthy diet. When possible, avoid soybean oil and soy protein isolate, a highly processed form of soy found in protein bars, frozen veggie burgers, canned soup and other processed foods. Those isolated, super-processed forms of soy don’t boast the health benefits of the whole soybean.
  • Opt for organic when possible. It’s estimated that a whopping 93% of soy crops in the U.S. come from genetically modified seeds also treated with pesticides. If available and the budget allows, choose organic soy products.
  • Look for fermented forms of soy. Fermented soy products like tempeh, miso and soy sauce are the cream of the crop thanks to the health-promoting benefits of gut-friendly bacteria. Fermenting soy may also help reduce its allergenic properties and increase the availability of amino acids.

About the Author

Alexis Joseph, MS, RD, LD
Alexis Joseph, MS, RD, LD

Alexis is a nationally recognized nutritionist and media personality specializing in nutrition communications and intuitive eating. She founded Hummusapien, a multi-faceted food, wellness, and lifestyle website in 2011 and co-founded Alchemy Juice Bar + Cafe in Columbus, OH in 2014. Alexis also works as a writer, speaker, and nutrition consultant for food brands and commodity boards.


4 responses to “Is Soy Safe?”

  1. Avatar Redins Mot says:

    If you are a male growing past his late 30’s it would still be advised to stay away from soy because of the estrogen – like qualities. It is not beneficial to the testosterone/estrogen balance in the male body.

  2. Avatar Rachel says:

    What is wrong with GE soy (incorrectly referred to as GM’s in your article) do you have a study that shows they are bad for you? And all soy (organic or conventional) are sprayed with pesticides. The difference is that synthetic pesticides go through rigorous testing and approval, where as “organic” pesticides do not. I’ll take the tested and researched route, thanks.

  3. Avatar Randy says:

    I’m sorry if this has already been asked or is a silly question. Is it possible for soy to cause breast enlargement in men? If so, how much soy? Thanks

  4. Avatar Rich Kaelin says:

    To be clear, I am no expert. However, I have found the general rule of thumb for everything in life to be moderation. I don’t believe men need to avoid soy completely. I would not advise making it your sole source of protein. Small to moderate amounts in your diet will not affect anything, and it’s a well-balanced protein source. I eat dry roasted wasabi edame as a snack. Far lower in fat than peanuts, higher in protein, a 100 calorie serving has 10 grams of protein and 5 grams of dietary fiber. You don’t get a much better snack than that. As far as the anti-gmo craziness going on, I get the fear, but there is absolutely no evidence that these are bad for you. There is not even really good anecdotal evidence, let alone scientific evidence. That conversation seems mostly fueled by what would appear to be logical rather than what is proven. I doubt it’s very good to eat huge amounts of pesticides, but I agree with the comment below that I would rather consume tested pesticides over untested pesticides. We need to remember everything is a chemical, your body is essentially made up of chains of chemicals. Organic arsenic is indeed organic and occurring in nature. Yes, it is poison and will kill you. Natural and organic does not mean safe and nutritious, as many would believe. It’s probably a good idea if you have the money to avoid high doses of pesticide, but you can also pick and choose and spend your money wisely. Check out The Dirty Dozen, buying organic celery might make sense. It would be the first choice over say organic oranges, when money becomes a consideration. We all need to live with reality-based considerations. If the entire planetary food system went organic, more than half of the population would be forced to starve to death. That’s just a simple fact, as crop yields per acre from organic farming are far lower then those for modern agriculture. We should also consider that our life spans are far greater than they were when all farming was organic, and the General State of our nutritional well-being is far better. This is in no small reason due to the increased availability of fruits and vegetables in our diet. Everything in moderation people. I wouldn’t go on an all soy diet, but I also wouldn’t go on the grapefruit diet, an all milk diet, or the all meat low-carb diets so many seem to be attracted to these days. I have lost a lot of weight, ovet 120lbs, and I’m in Better Health than I have been in 15 years. I eat whatever I want, but I track it all. You can eat potato chips as a snack if you make them part of the balanced diet. I do so about twice a week, with a portion equal to 2 servings. I eat the lower sodium variety, and remember that it’s not all bad. Potato chips actually have a lot of potassium, which is great for regulating fluid balance and blood pressure. There is an upside to almost everything, and when you think about it potato chips get a bad rap, since they are a minimally processed simple food. Generally potatoes oil and salt. compare that to some other processed snacks. Everything in moderation, don’t panic and don’t go to extremes.

Leave a Reply

Your email address will not be published. Required fields are marked *

Never Miss a Post!

Turn on MyFitnessPal desktop notifications and stay up to date on the latest health and fitness advice.


Click the 'Allow' Button Above


You're all set.