Soy Much Confusion

whole soy foodsjpg

Chances are you have read some controversial headlines about soy: “Soy increases the risk of breast cancer,” or “Men should avoid soy.” Most of the research from these claims are studying highly processed soy products consumed by animals - not humans. These headlines create a lot of confusion about whether soy should be included as part of a healthy lifestyle.

The truth is, science tells us that soy in its whole or minimally processed forms has many health benefits when consumed regularly. Soy has the highest amount of protein of any legume, is high in iron and fiber, and has antioxidant and anti-inflammatory properties. To contrast with cow’s milk, a glass of soy milk has just as much calcium and twice the antioxidant content, but with limited saturated fat and none of the cholesterol.

For centuries, soy has been a staple in Asian cultures, where the prevalence of heart disease, stroke, diabetes, obesity, high blood pressure and osteoporosis are all historically much lower than in the United States.

Still want more information about the safety of soy? Let’s do some myth busting.

Myth: Soy contains estrogen

Reality: Soy is the #1 food source of healthy isoflavones (a type of phytoestrogen)

Phytoestrogens are estrogen-like compounds found in a variety of plant foods such as beans, seeds, and grains, though they are concentrated in soy foods and flax. Isoflavones, the type of phytoestrogens found in soy, are significantly weaker than human estrogen and do not behave exactly like human estrogens in our bodies. This compound blocks some of estrogen’s effects and mimics others. Isoflavones are an active research topic, with current data indicating a wide variety of health benefits such as prevention of some forms of cancer and reduction in the risk of diabetes, heart disease and elevated cholesterol. There is also an association with greater longevity.

Myth: Consuming soy increases a woman’s risk of developing breast cancer and increases the risk of breast cancer recurrence

Reality: Studies comparing Asian cultures to those consuming a Western diet actually show us that the opposite is true

Not only is soy safe, but it has actually been shown to reduce breast cancer risk in the amounts consumed in Asia. Additionally, soy has been shown in some studies to reduce the risk of recurrence in breast cancer survivors.

  • One review showed that women averaging 1 cup of soymilk or ½ cup of tofu daily had a 30% lower risk of developing breast cancer versus women who avoid soy.  

  • The Shanghai Women’s Health Study showed that women who ate the most soy had a 59% lower risk of premenopausal breast cancer compared with those who ate the least amount of soy. 

  • A 2017 publication showed that American and Canadian breast cancer survivors who consumed the most soy had a 21% lower risk of dying of any cause over the 9-year study compared with people who had a low intake of soy. 

  • A 2012 review looked at the three studies on the link between soy and breast cancer survival. It showed that women who ate the most soy had a 29% lower risk of dying from breast cancer and a 36% lower risk of cancer recurrence. 

  • Another study showed an average intake of soy phytonutrients above 17 mg/day—the amount found in a cup of soymilk—may reduce breast cancer related death by as much as 38%.

  • As an added bonus, soy reduces the risk of endometrial cancer and ovarian cancer, and may reduce menopausal hot flashes. Somebody pass the soy!

Myth: Men should not eat soy

Reality: Soy has potential beneficial health effects for men, especially when it replaces meat, dairy and highly processed foods

Soy has been linked with a lower risk of prostate cancer. In a recent review of over 30 studies, higher soy consumption was associated with lower risk of the disease. This is especially true when soy is eaten in place of foods like meat and dairy.

Men are often concerned about eating soy because of phytoestrogen, but remember phytoestrogen is not the same as estrogen and clinical studies do not show soy foods negatively impact sex hormone levels in men. Don’t worry, soy will not cause man boobs!

Myth: Soy interferes with thyroid function

Reality: Soy does not affect thyroid function in people that have normal iodine levels

Your thyroid is a gland that controls metabolism in the body. There are many nutrients required for the thyroid to produce normal levels of thyroid hormone, iodine being the most important.  Though there have been some studies showing an underactive thyroid in people consuming soy, this was only true if their soy diets were very low in iodine. Adequate iodine intake is important regardless of whether or not you consume soy.

If you have an underactive thyroid and already take thyroid hormone replacement medication, know there are some things that may decrease the absorption of your medication, including soy, walnuts, iron, calcium and fiber. That is why you are supposed to take your thyroid hormone on an empty stomach and wait 30 minutes before eating.

Myth: Soy is always genetically modified

Reality: Much of the soy grown for human consumption is actually non-GMO

The truth is, not all soy is good for you.  It can be heavily processed and genetically modified, however most of the genetically modified (GMO) soy is produced to make soybean oil and cheap animal feed. While there is debate about the safety of GMO products, most non-GMO soy is produced for human consumption. To prevent indirectly consuming GMO soy, avoiding meat, dairy and processed foods is a good step. If you want to be certain about the soy products directly, opt for unprocessed or minimally processed organic soy (see below).

Bottom Line: Whole and minimally processed soy is a healthful food when eaten as part of a balanced diet, particularly when it’s used in place of meat and dairy.

Quality is key

Not all soy is created equal. It’s important to check ingredient lists to know what you are eating. Soy protein isolate, for example, is made from soybeans chemically engineered to ‘isolate’ the protein, and is added to many processed foods such as protein powders, veggie burgers and cereals. Choose whole, unprocessed or minimally processed forms to gain the health benefits. Like protein, eating too much soy may negate some of its health benefits. The general recommendation is to eat fewer than 3 - 5 servings daily.


Minimally Processed

  • Edamame (soy beans)

  • Tempeh

  • Miso

  • Tofu

  • Unsweetened soy milk

Highly Processed

  • Deep fried tofu

  • Soy-based desserts, meats & cheese

  • Soybean oil

  • Soy protein energy bars

  • Soy/isoflavones supplements

  • Soy protein isolate

Foods like tofu and tempeh take on a lot of flavor from herbs, spices and condiments, so they are very versatile and can be used interchangeably. If you don’t like the texture of tofu, try freezing and thawing it before cooking. This makes the tofu firmer, drier and a little less crumbly. Here are a few ideas to get you started:

  • Order miso soup in a Japanese restaurant

  • Snack on edamame

  • Make overnight oats or chia pudding with unsweetened soy milk

  • Use soy milk in a smoothie or in your coffee for a creamy dairy-free alternative 

  • Make a sandwich with tempeh, lettuce, tomato and avocado, otherwise known as a TLT

  • Add tofu or tempeh to a curry dish instead of meat

  • Marinate and bake tofu or tempeh and use it to top a salad or grain-based bowl

  • Try a tofu breakfast scramble

Your Challenge:

  1. This week, choose one meal to swap out meat for a minimally or unprocessed form of soy. Research different recipes in the Better app or on our Pinterest page.

  2. Familiarize yourself with where to find healthy soy based products in the grocery store.  You may not have heard of tempeh or edamame before, but your grocery store very likely has them. Don’t hesitate to ask a store employee for help if you can’t find the tofu. 

  3. Give soy a try!

EATNicole Landberg