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For decades, soy has been a controversial food. A quick Google search will yield just as many articles espousing its benefits as articles revealing its negative side effects. Everything from stronger bones (on the “pros” side) to digestive issues (on the “cons” side) is attributed to eating soy.
It’s hard to know which is the best, healthiest choice when presented with such widely divergent opinions.
So what’s the truth? Is soy a miracle food, chock-full of health benefits? Or is it a poor dietary choice, adding unnecessary hormones to your diet?
And the big question: how does soy affect your gut health?
Let’s explore the nutritional side of soy to find out whether this common food should be included in your diet.
What Is Soy?
Soy foods are those made from soybean, a legume. In the early 1900s, soybeans were used in the U.S. mostly as a commercial crop. Then, during World War II, when fat and oil imports were temporarily blocked, Americans began consuming soybeans.
Soy is present in many common foods but often flies “under the radar.” In fact, you may be consuming more soy than you realize!
Soy is consumed in many forms, including:
- Soy milk
- Soy sauce
- Teriyaki sauce
- “Veggie burgers”
In addition, Asian cuisine (Chinese, Japanese, Korean, Laotian, and Thai) uses soy products for many of its most popular dishes.
Soy also has a couple of forms, soy lecithin and soy protein isolate, that have become common ingredients in everything from energy bars to vegan products. Many of the meat substitutes that you find in grocery stores also use soybeans for their protein.
Is Soy Healthy?
This used to be a straightforward “yes” answer. And many people still consider soy to be a healthy food. After all, it’s a legume, and it’s not high in sugar or fat. So yes, soy can be healthy… when it’s grown in traditional ways.
Unfortunately, most of the soy crops grown today are not grown like they used to be. Instead, they are genetically modified and overly processed before they ever even see the inside of a grocery store.
Like any food, there are pros and cons to including soy in your diet. Let’s check out a few of both.
The Benefits of Soy
Soy is part of the legume family, one of the healthiest and most nutritious parts of any diet. There are a number of reasons why soy, in the correct form, should form a part of your diet.
Soy is an amazing source of antioxidants! It contains isoflavones, such as genistein and daidzein, which mimic estrogen but also help your body defend itself against the damage caused by free radicals.
The antioxidant power of isoflavones can reduce inflammation and lower the risk of cardiovascular disease.
Soy may also contribute to stronger, healthier bones, according to recent research. During the trial, soy isoflavones were shown to increase bone mineral density by a whopping 53%.
Soy isoflavones also reduce bone resorption, which is a natural process that breaks down older bones to assimilate them as part of creating new bones. While some bone resorption is a good thing, if it occurs at too high of a rate, it can decrease bone mass, leaving you at risk of a fracture or broken bone.
The same study above showed that soy isoflavones decreased the bone resorption marker by 23%, with the greatest results seen in menopausal women.
Lowers the Risk of Type 2 Diabetes
A recent study showed that women who eat more soy have a lower risk of developing type 2 diabetes. The study included soy, soy proteins, and soy isoflavones.
Researchers also studied the relationship between soy and type 2 diabetes in men but were unable to make any correlation.
Supplies a Complete Protein
For anyone following a vegetarian or vegan diet, soy is a powerful source of non-animal protein. In fact, soy is a “complete” protein, meaning that it contains all nine of the essential amino acids that your body can’t produce on its own.
Since soy is often used to make vegetarian products, including meat, cheese, and milk, it’s an easy substitution that tastes good while still providing some much-needed protein.
Increases Cardiovascular Health
Eating a diet high in soy can also lower your risk of cardiovascular disease, including stroke or coronary heart disease.
A review of numerous studies shows that a diet including an average of 25g of soy daily can lower LDL (bad) cholesterol by 3-4% over a six-week period. It also moderately increases HDL (good) cholesterol.
The strongest results were seen in study participants who consumed whole soy products, such as soy milk, soybeans, and soy nuts. Soy protein without isoflavones only produced a minimal cholesterol-lowering effect.
The Drawbacks of Soy
Soy has gotten pretty strong support in some parts of the scientific community.
However, it’s important to realize that most of the negative findings regarding soy are not based on foods made from whole soy. Rather, they are based on products (such as energy bars) that are made from soy protein isolates—where the protein has been isolated from the soy.
During that process, many of the nutrients in soy, including vitamins and minerals, are stripped away. And depending on how the final product is made, unnecessary chemicals may be added.
Elevated Hormone Levels
Remember those isoflavones we discussed earlier? These are the compounds responsible for many of soy’s biggest benefits, including increased antioxidants.
Well, it turns out that isoflavones aren’t entirely beneficial. Isoflavones can be an endocrine disruptor, meaning they mimic estrogen in your body. And even though this plant-based estrogen is much weaker than that produced by your body, it can still result in hormone overload.
The resulting side effects of too much estrogen can include:
- Reduced fertility
- Decreased thyroid function
- Earlier puberty in females and later puberty in males
Increased Digestive Issues
One of the biggest questions revolving around soy is: does soy cause digestive problems? The short answer is yes, and we’ll explain why.
First, soybeans are high in phytic acid, which binds to specific nutrients and makes them difficult or even impossible to absorb. This can cause vitamin and mineral deficiencies when the phytic acid binds to zinc, iron, calcium, or other nutrients.
On top of that, those undigested particles can cause a number of digestive issues, including gut infections, gut irritation, or a leaky gut.
Soy can also cause digestive discomfort, such as constipation, bloating, and nausea.
Soy is one of the top eight allergenic foods, so soy allergies are incredibly common. Usually, it’s caused by an allergic reaction to soy protein, which results in an immune response.
Some signs of a soy allergy include:
- Breathing issues: wheezing and shortness of breath
- Flushed skin
- Tingling, especially around the mouth and lip
If you have or think you have a soy allergy, read all food labels carefully. Soy products have become increasingly widespread and it can be found as an ingredient where you least expect it… even in some chocolates!
Tips for Adding Soy to Your Diet
If you want to eat products with soy to get its benefits, read labels carefully and choose organically grown soy.
Fermented soy is also a great option, and foods such as miso, natto, or tempeh fall into this category. You’ll still get the benefits of consuming soy without the negative side effects. And as a bonus, all three of those fermented foods are probiotic-friendly, giving an extra boost to that beneficial gut bacteria.
Here are some other tips for including soy in your daily diet:
- Choose whole soy foods such as soy milk, soy bread, tofu, and tempeh.
- Stick to foods are made from whole soybeans, not soy isolates.
- Make sure soy-containing products, such as cereal bars, are made with soy protein, not added isoflavones.
- Read labels carefully, particularly the salt content. Many soy foods, such as soy sauce, tend to have a high amount of salt, which can cause health issues such as bloating, headaches, high blood pressure, and kidney disease.
You can also measure by isoflavones. Each gram of soy protein (in whole soy products) contains approximately 3.5 milligrams (mg) of isoflavones; for maximum soy benefits, you’ll want anywhere from 30 to 50mg of isoflavones daily.
Here’s an idea of how much you’d need to eat or drink to reach the recommended amount:
- Half a cup of soybeans: 40 to 75mg
- 250 ml of soy milk: 15 to 60mg
- 115g (one block) of tofu: 13 to 43 mg
- One container of soy yogurt: 26mg
- One teaspoon of soy sauce: 0.4 to 2.2 mg
Protecting Your Gut
Since soy can cause digestive issues, you’ll want to take steps to keep your gut healthy if you add or increase soy in your diet.
One of the surest ways to boost your gut health is by adding probiotics to your diet. Probiotics help shore up the strength and numbers of “good” bacteria, crowding out the “bad” gut bacteria colonies and restoring a healthy bacterial balance.
Certain foods and drinks are known to be probiotic-friendly. There are even some soy foods on the list, but they aren’t the processed, prepackaged options; they’re products made with whole soy or fermented soy.
Try adding these probiotic-friendly foods to your diet.
- Apple cider vinegar
- Probiotic yogurt
- Soft cheeses (some of them)
Most of these foods gain their probiotic qualities through fermentation. Unfortunately, that also leaves a very specific taste and smell, which not everyone will like.
If you can’t or don’t want to consume these, you can also add probiotics into your diet through supplementation.
Probiotics can also be consumed as a supplement. But with so many on the market to choose from, it’s essential that you pick one that will give you the maximum “bang for your buck” in terms of effectiveness.
Look for a probiotic supplement that contains the spore Bacillus. This rich strain occurs organically in soil, and it has powerful, efficient results.
Our favorite is this one from Just Thrive, which includes an exclusive Bacillus super strain, HU36. Not only does it give you the probiotic support you need to restore your gut microbiome, but it also gives a boost to your body’s antioxidant-producing system.
Survivability is also hugely important with probiotic supplements. They travel through a pretty harsh digestive environment before they get to your gut: bile, enzymes, stomach acids, and more.
This one from Just Thrive has a strong endospore shell that protects it on its journey to your gut so that it “arrives alive” every time.
So, is eating soy bad for you?
The answer depends largely on what form of soy you’re consuming. If you stick to non-GMO, whole soy products such as soybeans and soy milk, your body will thank you. This is also true of fermented soy products such as natto or tempeh, which are rich in probiotics and thus great for your gut health and overall wellbeing.
In general, though, the benefits of soy far outweigh its drawbacks—especially if you pair them with a gut-boosting probiotic.
As long as you choose the right soy products, they can certainly play a strong role in your healthy diet!
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