The Truth About Soy
I've been eating a plant-based diet for a while now, and almost every time I talk to someone about it, they assume the following:
You shouldn't eat soy.
Naturally, I've never really believed it in the strictest sense. As I often do when there is a debate about foods that people have eaten for thousands of years, I chose to accept a softer version:
It's bad for you to eat too much soy….or any one food really.
This is why, for the past twenty years, I have eaten soy nearly every day without worrying that it's bad for our health.
My laid-back approach to soy has worked well so far but I decided it was time to examine soy more scientifically.
Does soy really hurt you?
First, the simple truth: hyper-processed foods are bad for you. This means that the soybean oil in many foods is bad for you.
Because it is not a whole food, not because it’s soy.
There are more rules to follow when it comes to tofu, tempeh, and even whole soybeans, which are minimally processed kinds of soy.
Many studies come out on both sides, but when we really look at it, it's easier to see that soy is good for you. No, it doesn't cause breast or prostate cancer (in fact, it might help stop them!). It also doesn't give men man-boobs (we don't know yet if it helps stop them!).
Let's look at why.
Soy products can make it easy to forget that soy is a bean, as they are an ingredient in many foods that don't look like beans. Should you order edamame as a starter before your veggie sushi? That's whole soybeans steamed in their pods.
People in the East have eaten a lot of soy for thousands of years. Even though many people assume soy is bad for you, it may be one reason why the health of people in the East is better than people in the West.
It's not really a surprise. Soybeans are beans, full of healthy things like fiber, which is known to fight cancer.
But there's a good reason for the debate over soy: it contains isoflavones, a type of phytoestrogen. A food with something like a hormone in it? That sounds scary..
However, phytoestrogens are not the same as estrogen, and not all of the bad effects of estrogen or substances that act like estrogen are present.
Dr. Michael Greger says the following:
Some organs respond well to estrogen, while others may not respond well at all. For instance, having a lot of estrogen in your body can be good for your bones but can also make you more likely to get breast cancer. In an ideal world, your body would have what's known as a "selective estrogen receptor modulato," which would make some tissues more estrogenic and others less estrogenic. That looks like what soy phytoestrogens are.
Soy's phytoestrogen is exponentially weaker than real estrogen. Also, the isoflavones can bind to the body's estrogen receptors, which means they can have weak estrogenic or even anti-estrogenic effects.
Because of this, soy seems to lower the risk of breast cancer. It also has many other health benefits for most people, such as making bones stronger, lowering the risk of prostate cancer, and lowering the risk of heart disease.
This message is not at all like the ones most of us have gotten from our friend, the internet.
Why there are so many different stories about soy
Many people say soy isn't good for us, but it seems like it is.
For several reasons.
Because a lot of the early work on soy was done on mice—first.
The American Institute for Cancer Research (AICR) says that the early studies that showed soy to cause breast cancer were mistaken because rodents do not metabolize isoflavones the same way people do.
Since then, many studies on people have either shown that soy protects against breast cancer or has no effect at all. Because of this, it's still not clear if soy is good or just neutral when it comes to the risk of breast cancer. Also, because it's a bean, soy that hasn't been cooked has fiber, which is known to help fight many types of cancer.
Second, soy has different effects on different people based on their race and hormone levels. The Harvard School of Public Health says that soy may work more like estrogen in women before menopause and more like an anti-estrogen in women after menopause. This means that tests on different groups of women will produce different results.
For instance, people who had been diagnosed with breast or prostate cancer used to think that soy might be bad for them. Not only that, but newer studies have shown that it doesn't stop the growth of these cancers.
Once more, Harvard Health says that the results may be different depending on the type of soy that was studied (whole, processed, fermented, unfermented, etc.). Many people think processed soy has more isoflavones than raw soy, but this isn't always the case because processing takes away many of them. To say it again, it's not bad because it's processed soy; it's bad because it's processed.
Can you have too much soy?
In a way, but not the way most people think.
It's not bad since it's made of soy... Really, too much of any food is bad for you!
When you eat too much of the same thing, you can't get as many nutrients from other foods. Dr. Joel Fuhrman says that two to four meals of soy a week is a healthy amount. "1 to 2 standard servings daily of whole soy foods, such as tofu, soy milk, edamame, and soy nuts," according to the AICR, is a healthy amount of soy. In fact, this amount may even be protective for breast cancer survivors a year after their diagnosis.
Does soy make guys fat? Does soy make men grow breasts?
No, as long as you’re not having insane amounts of it. This myth all started with one. To add to that, the problem went away when the man stopped drinking so much soy milk.
Fuhrman also points to a number of studies that show eating soy has no significant effect on testosterone or estrogen levels, sperm count, or male fertility in general.
Soy protein powder and IGF-1.
People say that soy protein is the most complete plant protein because it has the same amounts of all nine necessary amino acids as animal proteins. But for a while, some people were worried that the "completeness" of soy protein (and the high concentration of this protein in soy protein isolate) caused higher levels of a hormone called IGF-1 in the blood, just like animal protein does. IGF-1 has been linked to the growth of cancerous tumors.
But since then, it has been proven that soy and other plant proteins don't really raise the amount of free IGF-1 in the blood because they also tend to raise the amount of IGF-binding proteins.
Still, remember that soy protein powder is not a health food like raw soy, even though it doesn't raise serum IGF-1. Protein powder might be the best way to get extra protein for some people, but it's never quite as healthy as getting protein from whole foods.
Now we come to the question that almost all vegans have thought about at some point...
Is tofu good for you?
Yes! Dr. Michael Greger says that tofu and tempeh, which are made with gentle processing, are only half as healthy as whole beans... But he says that tofu and tempeh are good foods because they are made from whole beans.
Also, we already know that the isoflavones in soy are safe, so we can eat our favorite tofu several times a week (maybe even more often than that) without thinking.
But no, this still doesn't mean that we should order our favorite Thai coconut soup with deep-fried tofu. Not every day, but every once in a while.
It looks like the old plan to moderate, not avoid, foods that cause trouble has worked again.
And when it came to soy, I probably didn't need to feel bad about the busy weeks when we ate tofu stir-fry three or four times for dinner and had leftovers for lunch a few times.
Soy shouldn't be the main thing you eat. It shouldn't be just one food. When you eat a variety of whole foods as part of a plant-based diet, we have our answer: soy is good for you.