IS EATING SOY HEALTHY?: THE DOC AND CHEF SHOW EP. 2 SCIENCE AND RECIPE
IS EATING SOY HEALTHY?
Soy is one of the most controversial topics in nutrition. Many people are concerned that soy consumption will lead to “man boobs” (the medical term is “gynecomastia”) in men or breast cancer in women.
It has been shown that over-exposure to estrogen can increase a woman’s risk for breast cancer.[1] And because soy products contain plant-derived estrogen-like substances, called “phytoestrogens” many people believe that women should avoid soy. But in fact, soy has many health benefits.
With regards to breast cancer, regular soy consumption, especially when started earlier in life, decreases the risk of breast cancer by 30%.[2] In fact, if you look at population data, the parts of the world where soy consumption is highest, such as Japan and some areas in China, have the lowest rates of breast cancer.[3] Unfortunately, when women from these areas immigrate to the United States, which has one of the highest rates of breast cancer in the world, their risk for breast cancer markedly increases.[4] This increased risk is felt to be related to Westernization of their diet. In women who have had breast cancer, regular soy consumption has been shown to lower the risk of recurrence.[5]
How do phytoestrogens lower the risk of breast cancer?
Phytoestrogens weakly bind to the estrogen receptor in breast tissue, preventing regular estrogen from binding and overstimulating breast tissue growth.[6]
However, it may make a difference in what type of soy is consumed. There is some evidence that highly processed forms of soy, like soy protein isolate or textured vegetable protein, may increase the risk of breast cancer.[7] So the idea is to eat soy foods as “close to the ground” as they were grown. These include whole bean foods, such as edamame and tempeh, as well as minimally processed foods like soy milk, tofu, soy sauce and miso.
Soy also has many other health benefits; it can help lower blood pressure, lower cholesterol, decrease the risk for heart disease, help control blood sugars and promote bone health.[8] It has even been shown to reduce the risk of prostate cancer in men![9]
Does eating soy give you man boobs?
So back to man boobs…what really causes them? There are a lot of things that can cause men to develop enlarged breast, including certain medications and endocrine diseases.[10] But one of the most common causes today is obesity. The adipose tissue that stores fat also contains an enzyme called aromatase. Aromatase can covert testosterone in men to estrogen, and because estrogen promotes breast tissue growth, increase estrogen levels can lead to enlarged breasts (the lower testosterone levels also can contribute to erectile dysfunction).[11] This is also one reason obesity is a risk factor for breast cancer in women.[12] Women also make some testosterone (just not as much as men). This can be converted to estrogen by aromatase, and higher levels of estrogen increase the risk for breast cancer.
So, is eating soy healthy? The bottom line is that soy is good for you. Ideally you should have 2-4 servings a day to maximize the health benefits, so enjoy some tofu today!
Looking for more soy info? Check us out on the local news talking about soy!
Resources
[1] Breast Cancer Res. 2003;5(5):239-47
[2] Br J Cancer 98, 9–14 (2008)
[3] Breast Care (Basel). 2015 Dec;10(6):372-8
[4] British Journal of Nutrition, 115(10), 1769-1779
[5] CMAJ. 2010 Nov 23;182(17):1857-62
[6] World J Clin Oncol. 2014 Oct 10;5(4):705-12
[7] https://foodforbreastcancer.com/foods/soy-protein-isolate
[8] Nutrients. 2016 Nov 24;8(12):754
[9] The American Journal of Clinical Nutrition, Volume 89, Issue 4, April 2009, Pages 1155–1163
[10] https://www.ncbi.nlm.nih.gov/books/NBK279105/
[11] Endocr Relat Cancer. 1999 Jun;6(2):315-24
[12] CA Cancer J Clin. 2017 Sep;67(5):378-397
RECIPE
Air Fried Tofu
1 block of extra-firm tofu, frozen overnight and then gradually defrosted in the fridge for 24 hours *
Marinade
1/4 cup coconut aminos (tamari, Braggs, or low sodium soy sauce, are good subs)
1 tablespoon maple syrup
3 clove garlic, minced
2-3 teaspoons sriracha (optional)
3 tablespoons of natural, creamy peanut butter (tahini or sunflower seed butter for nut-free)
Juice of 1/2 lime
Zest of about 1/3 of a lime
2 garlic cloves, minced
1/2 " fresh ginger root, minced
1 tablespoon coconut aminos (tamari, Braggs, or low sodium soy sauce, are good subs)
1 tablespoon maple syrup
1/4-1/3 cup water
Directions for Sauce
Add all the ingredients, except the water, to a small bowl and begin to whisk well. Slowly drizzle in water as needed. Taste and adjust for flavor.
Can be used immediately or chilled for later.
Can be stored in the fridge in a sealed container for 5-7 days.
Makes nearly 1 cup
Directions
Freezing and then defrosting tofu (regular, not silken) helps the tofu soak up more marinade.
"We’ve often wondered why some tofu in Chinese restaurants has a distinctive spongy texture that allows it to soak up more of the sauce in a dish. This texture is produced by freezing the tofu solid before thawing and cooking it—a method that was originally used in China (and Japan) to preserve tofu during the winter months. Tofu is about 86 percent water; as it freezes, the ice crystals expand, pushing apart the protein network. When thawed, the water drains away, leaving the tofu with a spongy consistency that is highly absorbent."
-CooksIllustrated.com
When your tofu has thawed, you'll want to squeeze as much water out as you can - I use a tofu press and gradually increase pressure for about 30 minutes. Stand the tofu press up in the sink and allow the water to pour out gradually.
Next, add the marinade ingredients to a sealable reusable bag (Ziploc) and mix. Cut the tofu into cubes and add to the bag. Pull out as much air as you can and seal. Gently massage with your hands, making sure all cubes are covered. Place in fridge for several hours.
Add tofu to a preheated air fryer at 425. Fry for 10 minutes, flip and 10 minutes more.
Drizzle with peanut sauce. Add brown rice, steamed veggies for a meal that really rocks.
*We didn’t talk about freezing the tofu in the video. This recipe illustrates how to do that, although it is not necessary.
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