Breaking Down the Myths About Soy

People have been enjoying soy and reaping its health benefits for thousands of years, but there are still myths circulating about soy and soy products.

The Weston Price Foundation (WAPF), the Atkins Diet and the Paleo Diet, along with the meat lobby industry have all come out strong against soy. But what’s their angle? As the Guardian points out, the shady origins of the anti-soy propaganda can be traced back to a group that tries to scare people away from soy by citing results of scientifically flawed animal experiments.

WAPF is a multi-million dollar organization that claims to be dedicated to “restoring nutrient-dense foods to the American diet through education, research, and activism,” by lobbying for raw milk and “grass-fed” beef. The majority of the fear-mongering around soy is a direct result of misinformation disseminated by the WAPF’s relentless anti-soy campaigns.

The organization cites scientifically flawed studies that claim saturated animal fat is essential for good health and that animal fat intake and high cholesterol levels have no link with heart disease or cancer. The organization also goes as far as to say that vegetarians have lower life expectancy than meat-eaters, and that historically humans have always eaten large amounts of animal fat.

All this contradicts all the leading health advisory bodies in the world, including the World Health Organisation, American Dietetic Association and the British Medical Association. So what’s the unbiased truth?

The Truth About Soy

In reality, there are myriad of health benefits of soy foods, including protection against diabetes and breast cancer, as well as improved bone health and brain function. Dr. Michelle McMacken, an NYC-based internal medicine physician who aims to empower people to lead a healthy and kind plant-based diet, recently tackled the myths about soy in an Instagram post.


  • Soy contains isoflavones, a type of phytoestrogen that is 1000 times weaker than human estrogen & does not behave exactly like human estrogens in our bodies. Isoflavones block some of the estrogen’s effects & mimic others, generally resulting in health benefits; they also have antioxidant & anti-inflammatory properties.
  • Soy has the highest protein & fat content of any legume & is high in iron & fiber.
  • While soy does not contain estrogen, animal foods do, including “grass-fed” and “organic” meat.
  • Soy has been a staple in Asian cultures for centuries, and their incidence of coronary artery disease, hypertension, ischemic stroke, hormone-dependent cancers, osteoporosis, postmenopausal hip fracture, diabetes, and obesity are all markedly lower than in the United States.


  • Soy has been shown to prevent breast cancer in the amounts consumed in Asia. A 2008 review showed that women averaging 1cup of soymilk/ 1/2cup of tofu per day had a 30% lower risk of developing breast cancer vs women who avoid soy.
  • Soy has also been shown in many studies to reduce the risk of recurrence in breast cancer survivors. A recent study showed that breast cancer survivors who consumed the most soy had a 21% lower risk of dying of any cause over the 9-yr study, compared with low-soy consumers.
  • Soy reduces the risk of endometrial cancer & can reduce menopausal hot flashes.
  • Soy is the #1 source of isoflavones and may provide protection against ovarian cancer, multiple myeloma, and breast cancer.


  • A large 2010 systematic review showed that soy does not affect testosterone levels, sperm concentration, or sperm quality. Soy may lower the risk of prostate cancer by up to 50%.
  • 2003 Department of Health’s committee on toxicity report noted that there was no evidence that people who regularly eat high quantities of soy, such as the Chinese and Japanese (populations that have been consuming soy for thousands of years), have altered sexual development or impaired fertility.
  • “Moobs” (man boobs)  is another of the heavily circulated soy myths with no actual basis in scientific fact. Clinical studies in men show that isoflavones do not affect testosterone levels or circulating estrogen levels. Even at levels of isoflavone exposure significantly higher than those of a typical Asian male consuming a soy-rich diet, isoflavones have not been found to have feminizing effects.


  • Soy does not affect the thyroid in people with normal thyroid function and iodine levels. Whether or not you eat soy, you should meet your daily iodine needs (150mcg/day). If you take thyroid hormone, you may need the dose adjusted if you change your soy intake.


  • Soy lowers blood pressure & LDL cholesterol.

And as Michelle McMacken notes, even though some worry about estrogen and GMOs/pesticides from soy, most dietary estrogen comes from dairy and meat products. McMacken says, “Unlike soy phytoestrogens, animal estrogens DO mimic human estrogen in our bodies. Similarly, most GMO soy is used to feed chicken, pigs, & cattle, which are then consumed by people. Much of the soy grown for human consumption is non-GMO.”

Many try to make a connection between soy and cancer, but as John Robbins, author of the international bestseller Diet For a New America points out, “Despite the allegations of those wishing to build a case against soy, the evidence strongly suggests not only that soy does not promote cancer, but that it reduces cancer risk.” The protease inhibitors found in soybeans have been shown to reduce the incidence of colon, prostate, and breast cancer in humans. Robbins also notes, “The anti-soy crusade has needlessly frightened many away from a food source that has long been a boon to humankind, a food source that can if we are respectful of our bodies and of nature, nourish and bless us in countless ways.”

The Truth About Soy

Soy is safe, smart, and infinitely kinder than a meat-laden diet. But of course, soy foods are just one option in a nutritious, animal-friendly diet, and it’s easy to be a healthy vegan without touching tofu or sipping soy milk if you’d prefer to limit your soy consumption. Other excellent protein sources include lentils, nuts, beans, peanuts, seeds, chickpeas, green veggies, and whole grains. Soy milk provides the same amount of calcium, and twice the antioxidant content, as cow’s milk.

Consuming too much soy may negate some of the benefits of avoiding animal protein. Dr. Michael Greger, a physician, author, and internationally recognized professional speaker, recommends no more than three to five servings daily. As with all foods, moderation is key!

Nutrition Resources

To learn about the many benefits of soy, check out one of the following resources:

  •, the latest in nutrition-related research delivered in easy to understand video segments brought to you by Dr. Michael Greger
  • The Skinny on Soy, a comprehensive and well-researched book by Marie Oser, a best-selling author, healthy lifestyle expert, and environmental advocate with a focus on nutrition and its role in disease prevention.
  • Food as Medicine, a program that explores the power of a plant-based diet for optimizing health, led by Dr. Michelle McMacken, an NYC-based internal medicine physician
  • PCRM, for general information on the health benefits of a plant-based diet


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