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Soy has gotten a bad rap throughout the years, but many of the concerns have been proven to be untrue
Ah, the humble soybean. Did you know that the United States is the world’s No. 1 soybean producer? Just four Midwestern states — Illinois, Indiana, Iowa and Minnesota — are responsible for growing nearly half of the country’s soybeans.
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But that’s not the kind of information you came here for. No, you’re here because you’re trying to figure out: What’s the deal with soy, anyway? Is it good for me? Bad for me? Somewhere in between?!
“I can understand why people are sometimes concerned about soy,” says registered dietitian Beth Czerwony, RD, LD, “because there’s a lot of conflicting information out there and not a lot of definitive research. It can all be very confusing for consumers to try to figure out.”
Czerwony is here to help us through the many questions about soy, from whether it’s healthy to how to include it in your diet.
Throughout the years, soy has gotten a bit of a bad rap that seems to persist, even though science has shown soy to be safe and healthy.
So, why all the worries? In North America at least, soy has a complicated health history. For decades, research studies reported conflicting information about soy, and various health organizations issued recommendations around whether or not soy was healthy — or even safe.
Czerwony shares the pros and cons of eating soy and answers some of your biggest questions about it, including how certain beliefs have evolved or been completely debunked throughout the years.
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The phytonutrients in soy are called isoflavones, and isoflavones are phytoestrogens, which means they act like the hormone estrogen in the body. For a long time, people worried that eating soy would increase their estrogen levels, which they thought could impact hormones, affect fertility and cause breast cancer.
In time, though, research has shown that soy isoflavones act as a weak form of estrogen in the body. They just don’t have the power to wreak that kind of havoc — and on the other hand, soy is sometimes recommended as part of a menopause diet.
“The other interesting thing is that phytoestrogens may enhance the effectiveness of chemotherapy drugs and radiation,” Czerwony clarifies, “so if you’re going through cancer treatment, it’s worth asking your doctor about whether you should add soy to your diet.”
Many people worry that soy contributes to breast cancer, but research has consistently shown that soy-based foods do not increase your risk of cancer. Why do people think this? It goes back to the phytoestrogens we mentioned — the concern that eating soy would increase estrogen in the body, which would cause breast cancer.
But again, it’s proven not to be true.
“There has been a lot of research and a lot of concerns through the years about how soy may affect hormones, fertility and cancer,” Czerwony says. “But there has been no correlation that soy products cause breast cancer.” Given all of the available research on soy, the American Cancer Society, too, confirms that the benefits of eating soy seem to outweigh any possible risks.
Actually, some studies suggest a lower risk of breast cancer in women whose diets have included soy since childhood, particularly in Asian diets. Researchers suspect that fermentation plays a part, too.
“In Western countries, we’re having edamame and soy milk and a little bit of tofu, whereas Eastern diets typically include more fermented soy, like miso and soy sauce,” she shares. “But ultimately, if you’re worried about breast cancer, soy isn’t going to help one way or another.”
You might’ve heard that soy lowers bad cholesterol. You also might’ve heard that it has no effect. This is all the result of back-and-forth-and-back recommendations about whether soy is good for cardiovascular health.
In 2000, the U.S. Food and Drug Administration (FDA) allowed claims that soy protein lowered the risk of coronary heart disease. Based on that, the American Heart Association (AHA) encouraged adding soy protein to a diet low in saturated fat and cholesterol. But a few years later, the AHA changed its position, saying that cardiovascular benefits from soy isoflavones were “minimal at best.”
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It’s a topic that’s still being researched. In 2020, a large study found that people who ate at least one serving of tofu per week were 18% less likely to have heart disease than people who rarely ate it.
In other words, whether or not soy is good for your cholesterol is still up for debate. But at the very least, take heart in this: Absolutely no one is saying that soy is bad for your cholesterol.
In the hubbub around possible concerns about soy, it’s important not to forget that soy has a lot of known health benefits.
Most of the fat in soybeans is unsaturated fat, aka the “good” kind of fat, which has a variety of health benefits.
And what about the “bad” kind of fats? That’s called saturated fat, and soybeans have very little of it — unlike animal-based forms of protein (especially red meat), which are often high in saturated fat.
And get this: One serving of beef has 90% more saturated fat than one serving of tofu!
Soy doesn’t have as much protein as animal products, but it’s a great choice for a plant-based protein source:
“If you don’t want a lot of red meat in your diet, or generally want to get away from animal products, soy is a great addition as part of a well-balanced diet,” Czerwony suggests.
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Soy is even used as a basis for some types of protein powder, which can be a great alternative to whey protein for people who are sensitive to lactose or following vegetarian or vegan diets.
Eating soy-based foods is a great way to boost your fiber intake. One serving of cooked soybeans has 6 grams of fiber, including both soluble and insoluble fiber.
“Fiber helps keep your digestive system healthy and keeps you feeling fuller for longer,” Czerwony explains. An important note, though: Tofu is pretty low in fiber, and soy milk sometimes is, too. For the full fiber effect, you’ll need to turn to whole soy foods like soybeans and edamame.
Soy foods are a great source of vitamins, minerals and antioxidants, including:
Plus, many soy-based foods are enriched with vitamin B12, calcium, and vitamin D to help vegetarians get these much-needed nutrients.
If you have lactose intolerance, follow a vegan diet or just want to cut back on dairy, soy is a worthy replacement.
“It’s not as high in protein as cow’s milk,” Czerwony says, “but it’s a good alternative.”
Soy-based dairy replacement products include, well, just about every typically-made-with-dairy product you can think of, including milk, cheese, yogurt and ice cream.
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Czerwony flags a few characteristics of soy and soy-based products that you should bear in mind as you incorporate it into your diet.
Ready to add soy to your diet? Here’s where to find it:
If you’re not sure where to start, we can help with that, too. Czerwony shares a few recipes that feature soy products, including a tasty, tofu-based dessert!
Learn more about our editorial process.
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