Few foods are as interesting as soy. On one hand, soy is highly nutritious and is an excellent source of plant-based protein. Yet, many people suggest that you should avoid soy entirely. So, what’s going on. Is soy good for you or not?
As it turns out, soy is complicated. More so than most other foods.
While soy offers many important nutrients, it also contains antinutrients and phytoestrogens, along with other features that could damage your health. Thankfully, soy has been heavily researched, giving a strong sense of where soy might be a problem and where it’s powerful.
In this post, we’re digging into the controversy around carbs, just like we did for carbs and saturated fat. We’ll talk about the benefits of soy, along with the risks, and where current research is limited.
Is Soy Good For You?
- What Is Soy?
- The Health Risks Of Soy
- The Benefits Of Soy
- Why Is Soy So Complicated?
- Is Soy Healthy Or Not?
- Which Soy Products Are Best?
- Final Thoughts
What Is Soy?
Soybeans are a type of legume. They’re native to East Asia, although they are now grown throughout the world.
The legume is popular for many reasons, including the high protein content, the range of nutrients, and the low price. Because soybeans are inexpensive to produce, soy has become a critical protein for animals and humans.
You might see soybeans used on their own, but they’re more common as an ingredient in a wide range of vegan and vegetarian products.
Soybeans Versus Soy
Discussions of soy sometimes use the word soybean or soya bean instead of soy. While the words can be used in much the same way, soy generally refers to the protein that comes from soybeans. In contrast, the words soybean or soya bean are often used to refer to the legume itself.
We’re using the word soy in this post, as we’re talking about soybeans and all the products that are made from soy protein.
Of course, the effects will vary depending on the soy products that you choose. These differ in many ways, including their nutritional profile, level of processing, whether they’ve been fermented, and the amount of soy isoflavones.
The Health Risks Of Soy
Because soy is so controversial, we’re going to start by talking about the risks of soy, then move onto the benefits. However, while these risks and controversies are often discussed, they’re not strongly supported by research.
Isoflavones are a class of molecules found in foods, particularly legumes and soy has one of the highest concentrations of isoflavones. These molecules are often called phytoestrogens too, as their structure is similar to estrogen.
This similarity can mean that isoflavones act a little like estrogen in some situations.
As we’ll discuss later, the estrogen-like effect of isoflavones could be beneficial. Still, there are concerns about them too.
One issue is that if soy isoflavones act like estrogen, they could have feminizing effects on men, reducing testosterone levels. Such problems could be stronger if men are consuming large amounts of soy.
However, there is little evidence of such an outcome. When studies do find a link between soy and negative effects on men, the relationship appears to be weak and may be explainable in other ways.
Plus, as some authors have pointed out, soy consumption is common in Asian countries, which often have large populations. If there was a link between soy and negative effects on men, it would have shown up in those populations.
Like beans, soy contains antinutrients. These are compounds that can decrease the nutrients you absorb from soybeans.
Thankfully, soaking, fermenting, or cooking soybeans helps to decrease the antinutrient levels. Antinutrients mightn’t even be an issue with many soy products because they’ve already been cooked or fermented before you use them.
Besides, even if some antinutrients remain, you’re still absorbing and using more nutrients from soy than if you didn’t eat it.
The Omega 6 Fatty Acids
While soy mostly contains healthy fats, much of this is in the form of omega 6 and there is little omega 3 present.
Like omega 3, omega 6 is a type of polyunsaturated acid. Omega 6 is still important for our health, but many of us consume too much omega 6 and not enough omega 3.
This can be a problem, as a poor ratio of omega 3 to omega 6 may lead to increased inflammation and a variety of other health issues. If you’re going to include soy in your diet, it’s important to also focus on omega 3 rich foods to help keep your omega levels in balance.
Soy Can Affect Fertility
Research into soy and fertility is interesting. Some studies suggest that soy may help to increase fertility in women, while others have shown the opposite effect. This difference could be influenced by how the estrogenic effect of soy varies depending on the person’s estrogen levels.
Thankfully, most studies suggest that having between 10 mg and 25 mg of soy isoflavones each day does not cause any harm. That’s somewhere between 1 to 4 servings of soy-based foods each day (depending on the product you choose).
Keeping within those limits seems reasonable regardless, as varied diets are always the most powerful for health.
Soy is often genetically modified, which may make it less nutritious. Genetically modified soy might have more herbicide residues too and there are concerns that the genetic modification itself could impact health.
While there is little evidence that GMO soy is harmful, long-term research into GMOs is still ongoing. There could easily be effects that we don’t currently know about.
Thankfully, non-GMO soy can be found on the market too. Look for labels that say GMO-free or something similar. Choosing such products can help you avoid the entire problem.
Animal research suggests that soy can influence thyroid function. The effect appears to be much smaller and almost non-existent for humans, even when high doses of soy are consumed.
The main exception is that soy may interact with hypothyroid medication. If this is the case, then people taking medication for their thyroid may need to decrease their soy take. However, we’re talking about a special situation here, one that doesn’t apply to most of the population.
The Benefits Of Soy
While the potential risks might make soy sound like a poor choice, the legume offers plenty of benefits too. In fact, many healthy people and populations eat soy daily, suggesting that soy isn’t as concerning as we sometimes think.
A Fantastic Source Of Nutrients
Soy is an easy way to boost your nutrient intake, as soybeans contain decent amounts of folate, thiamine, phosphorous, copper, and vitamin K1. For a 3.5 ounce serving of soybeans, you get more than 16 grams of protein, 6 grams of fiber, and 9 grams of fat (most of which is unsaturated).
There are other important compounds present too, including antioxidants and plant-based chemicals. Even the soy isoflavones that we mentioned earlier are relevant, as they have been linked to some health benefits.
The various soy products are made in different ways, so each type has its own balance of nutrients.
For example, while tofu and tempeh are similar, one is made from soy milk and the other from soybeans. Tempeh is often higher in fiber and protein, while tofu can be lower in calories and contains more calcium.
There may be variation between brands too. You’ll need to check the ingredients for each product to find out what it has to offer.
Low In Carbs
Soybeans are surprisingly low in carbs – to the extent that they even feature on low carb and keto diets. They can be a helpful way to balance your macros, as they’re high in carbs and are a moderate source of fat. Black soybeans are even lower in carbs again.
Many soy products are low in carbs too. Some will even be designed for low carb diets.
Even if you’re not following keto, the low carb content of soy is important. High consumption of carbs, particularly simple carbs, may contribute to a variety of health problems. While that topic is under much debate, decreasing your carb intake and increasing healthy fats and protein instead is often a wise move.
May Decrease Heart Disease Risk
You might see soy promoted as a cholesterol lowering food. This is true, to an extent, as soy can decrease LDL cholesterol levels. However, the amount of decrease is slight and mightn’t influence heart disease risk on its own.
Still, a weak direct relationship between soy and cholesterol doesn’t stop soy from being heart-healthy. Soy remains a plant-based source of protein, one that won’t increase your cholesterol and doesn’t contain saturated fat.
So, if you replace some of your saturated fat intake with soy instead, you might decrease heart disease risk that way.
May Protect Against Cancer
Soy is a traditional ingredient in many Asian countries, with many people eating soy every day. Prostate cancer levels in these countries are lower than in Western countries, suggesting a link between high soy intake and decreased risk of prostate cancer.
A protective effect of soy has been found in experimental studies too.
Soy may also have a positive effect on breast cancer, partly because the phytoestrogens in soy can also block estrogen in some contexts. However, the effects here can be different depending on the person’s age, their menopausal status, and the type of breast cancer.
Here too, soy consumption could help protect against breast cancer. While the outcomes of research have been mixed, soy appears to either be protective or have no effect (so, it hasn’t been observed to increase breast cancer risk).
There are other potential cancer protective effects too.
Yet, interestingly, many people avoid soy because they’re concerned that it could increase cancer risk. That concern might be linked to the isoflavones, but there is no evidence for any cancer increasing effects in humans.
Soy has been linked to health improvements in other areas too, such as improvements in blood sugar and insulin levels. Such effects could be relevant for decreasing the risk of diabetes and improving blood sugar control.
Some theories also suggest that soy can help with menopause symptoms, including decreasing hot flashes, joint pain, and fatigue. Soy might even help with low estrogen levels following menopause and reduce related calcium leaching.
Many of these benefits have been suggested in some studies and populations but have yet to be widely proven. More detailed studies are needed to find out exactly how soy influences health and which types are best. Still, current research strongly suggests benefits and shows little evidence for harm from soy.
Soy Is Convenient
Soy has practical benefits too. It’s one of the easiest ways to increase plant-based protein intake, as so many different products use soy. Tofu and tempeh are two classic options. These can both be used as a meat alternative in vegan meals.
You can even find soy protein powder, which you can use in protein shakes and even in some baking.
We can’t forget about all the soy meat substitutes either. These can make a vegan diet much easier to follow.
Why Is Soy So Complicated?
Nutrition science is never as straightforward as it seems. Foods all contain a variety of compounds, which all influence the body in different ways. Plus, the impact of each component is influenced by what you’re eating at the same time, your body chemistry, your diet, your genetics, and countless other things.
The phytoestrogens make soy more complex than other types of food.
Not only can the effects of phytoestrogens be difficult to determine, but these can change depending on the level of estrogen in the person’s body. For example, in women that haven’t hit menopause, soy may have an anti-estrogen effect, while in post-menopausal women, the effect is estrogen positive instead.
Likewise, phytoestrogens may be beneficial, detrimental, or have no impact depending on the person and the situation.
Is Soy Healthy Or Not?
Soy is unusual, as it has a myriad of positive effects and the potential for just as many concerning ones. There’s much more evidence for the benefits of soy than any of the risks, which implies that soy is safe.
Soy may even be powerful for health if you replace some of your red meat and processed meat with soy instead.
Even so, soy is an ingredient to be careful with.
For one thing, there are some major gaps in our knowledge. While the studies haven’t proven many negative effects from soy, they have followed a variety of designs and have their limitations.
For example, research studies often look at a broad population and consider the statistical probability of negative effects. However, soy appears to affect different people in different ways, so studies could miss some negative effects if they only apply to a small population.
The sheer number of soy products is another area of concern, including soybeans themselves, soy milk, tempeh, tofu, miso, soy sauce, and soy-based meat alternatives. Other products may use soy as one of many ingredients.
This focus on soy makes it easy to overdo it and consume much more of the legume than you mean to. Doing so risks amplifying any negative effects.
In fact, the strongest evidence for problems with soy comes from very high levels of soy consumption. These factors suggest that soy is best when consumed in moderation. This way you get the good features without putting yourself at risk.
Remember too that most of the benefits we’ve discussed aren’t exclusive to soy anyway.
For example, replacing red meat and processed meat with any type of plant-based protein is likely to improve your heart health. In fact, many of the benefits from soy apply to other types of legumes, including beans, lentils, and chickpeas. Why not include a variety of these in your diet?
Which Soy Products Are Best?
Here’s another complicated thing about soy – soy products are all very different. They don’t just vary in nutrition either. There are also differences in the level of processing and in the amount of isoflavones.
You can see some of these differences in the lists below.
Unfermented Soy Products
- Tofu. Made from coagulated soy milk, tofu is often used instead of meat and takes on the flavor of other ingredients. The isoflavone content is relatively low (roughly 20 mg in a 3 oz serving).
- Soy milk. A popular plant-based milk that’s often made by boiling ground soybeans and filtering the mixture. The nutrient composition can vary dramatically, as some companies fortify the milk to make it more similar to dairy milk.
- Soy cheese. Various companies use soy to create a vegan cheese-like product. Soy cheese tends to be low in isoflavones but is often highly processed as well.
- Soybeans. Soybeans are sometimes served on their own too, either boiled or dry roasted. Such products are much less processed than tofu and soy milk, but the isoflavone content tends to be higher too.
- Soy meat. Vegan meat alternatives often use soy as an ingredient. Some, like Tofurky, use soy as the primary source of protein. Others include a variety of ingredients. Such products are useful, as they can often be cooked just like meat. However, they’re also highly processed and the nutritional content can vary wildly.
Fermented Soy Products
- Tempeh. This product is similar to tofu, except that tempeh is fermented and uses soybeans rather than soy milk. It is a little chewy and nutty, but will still work in many of the same recipes as tofu. The isoflavone content is higher than tofu, although lower than in whole soybeans.
- Natto. Another product that’s made by fermenting soybeans. Natto is an acquired taste, as it has a slimy texture and strong flavor. It is also notably higher in isoflavones than tempeh and tofu. Still, natto is sometimes called a superfood and can be a useful source of probiotics.
- Soy sauce. This Chinese sauce provides a strong umami flavor and is normally used in small quantities. It is traditionally made by fermenting wheat and soybeans, along with some salt. Non-fermented versions are sometimes produced too. These use chemical methods to create the flavor, tend to taste less appealing, and may be less healthy.
- Miso. This fermented soup is delicious and has been linked to various health benefits. It’s relatively low in isoflavones too. Plus, the soup can be simple or complex, giving you plenty of variety.
The healthiest soy products tend to be minimally processed, like tempeh and soybeans themselves. These retain all of their nutrients and are least likely to contain additives.
Options like tofu and soy milk may be appealing too, especially as their isoflavone content tends to be low. However, it’s important to pay attention to the ingredients label. Look for products that have few additives and no concerning ingredients.
Despite all the controversy, soy should be healthy for most people. This is especially true if you avoid heavily processed soy products, including some of the soy meat alternatives.
Be careful with the amount of soy that you eat too. It’s easy to overdo it with soy, as it is used in so many different foods. But, having too much increases the risk of any health problems.
Try using soy as just one of your plant-based sources of protein. Other legumes can help to fill in the gap, as offer a decent amount of fiber and protein. Don’t forget about other options either, such as nuts or even pseudograins like quinoa.
Varying your diet like this provides you with the widest range of nutrients, along with plenty of benefits. Plus, you’re not having large amounts of any one type of food, so the risks are minimal.