The nutrition world is filled with controversial topics, and soy is definitely one of them. I think you’ll be surprised to see that the science isn’t quite as controversial as it may seem. For most women, soy foods are a healthy choice. In this article we’ll cover the myths and facts surrounding soy, how to choose the healthiest soyfoods (and how to avoid the not-so-healthy ones), and clarify the most burning question – what the heck tofu and tempeh are made from. 

Soy Basics

Soyfoods contain something called isoflavones. In fact, they are the highest source of isoflavones. Isoflavones are plant estrogens and are also called phytoestrogens. This relationship to estrogen is at the root of most of the controversy surrounding soy. But these phytoestrogens do not behave the same as the hormone estrogen and actually have a lot of health benefits. Soy is a cornerstone of many traditional diets across Asia where it is common to eat 1-2 servings of traditional soy foods everyday. And it is linked to heart health, bone health, reduced hot flashes, and more.

Soy and Breast Cancer

Research increasingly shows that soy’s high isoflavone and antioxidant content are actually protective against cancers, including breast cancer and ovarian cancer, as well as other chronic diseases. In Asia, women who eat the most soy have lower rates of breast cancer compared to women who eat very little soy. However, it appears that women need to have begun eating soy in childhood for this benefit to hold true. For women with breast cancer, eating soyfoods may support greater survival and decreased chance of recurrence. Many prominent cancer organizations, including the American Cancer Society, agree that it is safe for women with breast cancer to eat soy. 

Soy and Thyroid Health

You may have heard that soy can negatively interfere with thyroid health, specifically increasing the risk of hypothyroidism, but for people with healthy thyroids soy is safe. If you have low thyroid function and are taking thyroid medication, then it’s advised that you do not over-consume soy and do not consume soy within a few hours of taking thyroid medication. 

Soy and Menopause

Many studies have shown that about 2 servings of soyfoods per day can help reduce the frequency and severity of hot flashes by 50%. 

Soy and Reproductive Health

The isoflavones in soy do not have any effect on hormone levels in men or women, including estrogen and testosterone. Isoflavones also don’t affect sperm or semen. 

Soy and Pregnancy & Children

You might also be curious whether soy is safe to eat during pregnancy as well as whether it’s safe for your little ones. The short answer to both of those questions is yes! Soy foods can be especially helpful in pregnancy to meet higher nutrition needs without relying heavily on more animal foods. Soy-based infant formula has also been the source of controversy, but the American Academy of Pediatrics agrees that soy formula is safe for full term infants (it is not recommended for preterm infants). Soy formula has been shown to cause less of an immune response compared to cow’s milk-based formula. 

Studies show that children who consume soy do not experience any abnormal changes in hormone levels or in the age at which they reach puberty. And don’t forget those added benefits later in life from consuming soy in childhood. 

Which Soy Foods To Choose + How Much

It’s important to know that the health benefits you just learned about apply to minimally processed soyfoods and aren’t necessarily true for the abundance of heavily-processed soyfoods available today (think nuggets, protein powders, and fillers). The processing of these soyfoods removes much of the isoflavones as well as other key nutrients responsible for the health benefits of soy. To reap the rewards and steer clear of any unhealthy effects, stick to minimally processed soyfoods. like tofu, tempeh, edamame, and soy milk. It’s also best to stick with about 2-3 servings per day. One serving is equal to about ½ cup of tofu, tempeh, or edamame; or 1 cup of soymilk.

Minimally-processed Soyfoods:

• Miso paste

• Edamame

• Tempeh

• Tofu

• Soymilk

Common Questions About Soy

Should you avoid genetically modified (GMO) soy?

When it comes to genetically modified foods, my recommendation is to err on the side of caution and avoid GMO foods whenever possible. An herbicide called glyphosate (known in the market as Roundup) has been labeled a probable human carcinogen by the World Health Organization in 2015, and the heaviest use of Roundup is on GMO crops. Because it is not out of the realm of possibility that this chemical could end up in the final foods, I think it is best to opt for organic soyfoods when possible. 

What is tofu?

Tofu is essentially curdled soymilk, similar to how cheese is made from curdled milk. Tofu originated in China where it has been made and eaten for over 2,000 years. Over that time, it spread to many other regions of Asia, becoming a staple food in many Asian cultures. It’s a wonderfully flexible ingredient with many types and endless uses. 

Types of Tofu

• Silken: undrained, unpressed, custard-like texture. Use in creamy or blended foods (smoothies, sauces, desserts). Great as an egg substitute!
• Firm/Extra-firm: pressed, packed in water (simply drain and pat dry before cooking). Absorbs flavors well. Great for stir fry, baked, crumbled, and grilled.
• Super Firm: very dense, high protein, not packed in water. Good choice when you’re in a hurry. Doesn’t absorb flavor as well and dries out easily.

Tofu Cooking Tips:

• Press it. Most tofu comes packed in water, so you must drain and press it. If you skip this step, your tofu won’t absorb marinades or get crispy when cooked. First, drain the water. Then, slice the block and gently press slices between paper towels or a dish cloth to soak up excess water. After you absorb as much water as possible, marinate or start cooking.
• Marinate it. After you’ve pressed tofu, it’s ready to absorb any flavor you introduce to it. Since even pressed tofu contains some water, exclude oils from your marinade (oil and water don’t mix!). Use vinegars or citrus juices as a base instead.
• Blend it. Tofu blends well into smoothies, sauces, and dressings to add creaminess, protein, and calcium (calcium-set tofu contains more calcium than Greek yogurt). It also makes great eggless quiches. 
• Crumble it. Crumbled, seasoned tofu takes on the texture of scrambled eggs or ricotta cheese. You can also crumble tofu into soups or chili for a “meaty” texture. It’ll soak up all the flavors of the broth.

What is tempeh?

Tempeh is made from fermented soybeans and has an appealing crumbled texture similar to ground meat. It originated in Indonesia. Because of its firm, dry texture, it can be easily sliced, cubed, and crumbled for a wide array of culinary uses including ground beef, bacon slices, and kabobs. In the United States, tempeh is less well-known than tofu, yet many find the texture of tempeh to be more palatable and easier to cook with compared to tofu’s spongy nature. Like tofu, tempeh is the ultimate chameleon, with the ability to take on almost any flavor. 

Tempeh Cooking Tips:

• Steam it. If you find tempeh to be too bitter straight out of the package, steaming or simmering it can help to remove bitterness and prepare it to better absorb marinades. (roasting in the oven works too!)
  • To steam: set up a steamer basket over a pot of boiling water and place the tempeh in the basket. Cover it and let it steam for 10-15 minutes.
  • To simmer: fill a saucepan with an inch or two of water, broth or marinade and bring it to a boil. Place the tempeh in the saucepan, cover the pot, reduce the heat and let the tempeh simmer for 10-15 minutes. Remove the tempeh from the liquid and pat it dry. 
• Marinate it. Submerge tempeh slices, cubes or crumbles in marinade of choice for at least 30 minutes or overnight if possible.
• Slice it thin. Tempeh can be sliced into any shape. Slicing it into about ¼ inch thick pieces helps it to become crispy on the edges while retaining a nice, chewy interior when sautéing or baking.
• Crumble it. Tempeh takes on the flavor of whatever it’s cooked in, making it a versatile way to add heartiness and protein to a meal. Add crumbled, grated, or cubed tempeh to spaghetti sauce, stew, chili, or curry.