Soybeans: History, Nutrition, Benefits And Uses

What’s the deal with Soybeans?

Find out…

Everything you ever wanted to know about soy, all in one place.

What Is Soy?

The soybean, also known as the soya bean, is a type of legume that has been used by humans for thousands of years. Soy has its roots in ancient East Asia and didn’t appear in North America until much later. Westerners used the legume to produce a wide array of products, from emulsifiers, to ice cream, to ink.

The soybean is the only plant-source of complete protein. This makes it a popular choice for people looking to eat less meat or abstain from it altogether.

Soy has a reputation for being controversial in the nutrition and science communities – no one can seem to agree on whether the soybean is a healthy or harmful. The fact is that many studies are available that seem to support both sides of the argument.

The History Of Soy

Soy can be traced all the way back to 1100 BC where it was first domesticated by farmers in China. A little over a thousand years later, the soybean found its way to Japan and began spreading quickly across the continent.

Fast-forward to the 1700’s as soybean seeds found their way to one of the first British colonies called Georgia. The seeds traveled across the country and were found throughout the corn belt states by the 19th century. During this time, soybeans were primarily used to feed livestock.

In the 1940’s, soybean supplies in the U.S. dropped dramatically as imports were cut off from China. American farmers started growing more soybeans to meet the growing demands caused by World War II. At this time soy was, being used to create industrial lubricants and plastics for military machinery and gear.

Scientists began looking at the soybean as an alternative to animal protein in the 1960’s. Fears were rising that soon, the earth’s population would outgrow its food supply. Soy, molds, and bacteria were studied for their viability as the “food of the future”.

Today, 31 states are involved in the soybean industry, with most of the supply coming from the midwestern states. Soy is used to make a wide variety of products and continues to shape American agriculture.

Foods And Ingredients That Contain Soy

Soy is pervasive in the American diet. Whole soy foods like tofu and natto are found in traditional Asian cuisine and in the U.S., while some products, like soy protein isolate and textured vegetable protein, are uniquely western products.

Western societies tend to rely more on highly processed foods for their soy intake, while Asian cultures incorporate more whole and fermented soy into their diets.

Edamame are young, firm soybeans that can come shelled or still inside their fuzzy green pods. Edamame are most widely consumed as a snack or appetizer, but can also be incorporated into salads, dips, and stir-fry.

Soy Nuts, despite their name, are not nuts. Soy nuts are simply soybeans that have been roasted in peanut or vegetable oil and salted. They are often enjoyed as a crunchy snack or used as a salad topping.

Tofu is a product made from soybean curds. It can be found in soft, firm and extra firm varieties. Tofu has a very mild flavor that makes it good for both sweet and savory dishes. Tofu can also be marinated and cooked in much the same way as meat, although the flavor and texture are very different from animal proteins.

Miso is a thick paste made from fermented soybeans. It is used as a condiment and has a salty, umami flavor that is characteristic of many Japanese dishes like miso soup.

Natto is made from whole soybeans that have been soaked, steamed, and fermented with the bacteria bacillus subtillis. The end result is a distinct dish that has a strong ammonia smell and a gooey, stringy texture.

Tempeh is an Indonesian staple that is made from fermented, cooked soybeans formed into a firm patty. Unlike tofu, tempeh is textured and has its own pleasant, nutty flavor.

Soy Sauce is a condiment made from fermented soybeans and wheat. It is one of the most widely used soy products throughout the world. Soy sauce has a deep umami flavor and is known for its high salt content.

Tamari is very similar to soy sauce but is made using little to no wheat. Tamari is a good choice for individuals with gluten sensitivity or Celiac Disease.

Soybean Oil is the main soy product produced in the United States. About 7% of the calories eaten in American come from soybean oil. This product is extracted from the soybean using a chemical solvent called hexane and can sometimes be found in hydrogenated form. Hydrogenated oils contain Trans Fats, which come with many health risks.

Soy Protein Isolate is a refined powder that has been separated from the other parts of the soybean. It is 90-95% protein and can be found in many protein bars, shakes, and supplements.

Soy Lecithin is a food additive that is used as an emulsifier. Emulsifiers allow fat and water to mix together without separating. Soy lecithin can be found in many foods like ice cream, margarine, candies, yogurts, and baby formula.

Textured Soy Protein, also known as Textured Vegetable Protein or TVP, is found in many meat-alternative products. Like soy protein isolate, TVP is separated from the other parts of the soybean and has a high protein content.

Soy Milk is made by soaking and grinding soybeans, boiling them, and filtering the boiled mixture. Soy milk is often found sweetened or flavored and is fortified with vitamins and minerals. It can be used to make many dairy-alternatives that mimic ice cream, yogurt, and cheese.

Industrial Uses Of Soy

Many people think of soy as solely a food product, but it has almost as many uses that don’t involve food at all.

Biodiesel is a fuel that can be made from soy and other natural materials. It is a cleaner-burning, more sustainable alternative to traditional fuels like petroleum.

Industrial Lubricants can be made from soybean oil and are used to make machinery and other types of equipment run more smoothly.

Adhesives can be made from soy flour mixed with a certain type of resin. These industrial glues are less harmful than their formaldehyde-based alternatives and are often used in carpeting.

Candles are more often being made with soy wax as an alternative to paraffin wax, which is a by-product of refined gasoline. Soy wax is cleaner burning, longer-lasting, and biodegradable.

Ink is traditionally made using petroleum, but some newer pens are being sold filled with soy ink. Petroleum-based inks can be harmful to the environment, but soy-inks are biodegradable and don’t contain any toxic ingredients.

Soy Nutrition Facts

Soybeans are mainly composed of water and protein. However, they do contain a good amount of carbohydrates and fat.

100 grams of cooked soybeans contains:

  • 140 calories
  • 12 grams of protein
  • 11 grams of carbohydrates
  • 4 grams of fiber
  • 6 grams of fat

Soy is the only plant source of complete protein. This means it contains all nine essential amino acids that the body cannot make on its own. Those essential amino acids are tryptophan, valine, threonine, isoleucine, leucine, lysine, methionine, histidine, and phenylalanine.

The fat in soy is mostly monounsaturated and polyunsaturated fat, which are considered to be the healthier types of dietary fat. Soybeans also contain a small amount of saturated fat.

Soybean oil contains about 50% linoleic acid. Linoleic acid is better known as Omega-6 fatty acid and is a prominent fat in the American diet.

Omega-6 fatty acids need to be balanced with Omega-3 fatty acids like those found in fish – otherwise, Omega-6’s can cause inflammation in the body.

Soybeans are high in a fiber called alpha-galactoside, which is considered a FODMAP. FODMAPS are foods that can cause symptoms in people with Irritable Bowel Syndrome. Symptoms seen in people sensitive to alpha-galactoside include gas, abdominal cramping, diarrhea, and bloating.

For people without IBS, alpha-galactoside can have beneficial effects. This fiber is fermented in the intestines by the microbiota, or gut bacteria. The gut bacteria then produce small chain fatty acids, or SCFAs.

These short chain fatty acids have many health benefits including reducing the risk of colon cancer and improving the ability of the immune system to fight disease.

Soy also contains many vitamins and minerals. 100 grams of cooked soybeans contains:

  • 17 mg Vitamin C
  • 111 mcg Folate
  • 3 mg Thiamine
  • 145 mg Calcium
  • 5 mg Iron
  • 60 mg Magnesium
  • 5 mg Manganese
  • 539 mg Potassium


Anti-nutrients are often brought up in discussions about soy. As the name would suggest, Anti-nutrients prevent your body from absorbing certain beneficial nutrients found in food.

Trypsin Inhibitors prevent protein digestion in the stomach and small intestine, which reduces the amount of protein you can absorb from soy and other foods eaten along with it.

Phytates, or Phytic Acid, prevents your body from absorbing vitamins and minerals from food.

The good news is that these anti-nutrients are deactivated almost entirely when soy is cooked or fermented. This is why soy must be cooked before being eaten – otherwise, it is considered poisonous.


Much of the controversy surrounding the health of soy involves phytochemicals. Phytochemicals are naturally found in plants and can serve as defense mechanisms, pigments, fungicides, or attractants for bees and other pollinators.

While phytochemicals have many benefits for the plant they come from, they can also interact with the human body and have varying effects.

Isoflavones are phytochemicals found in soybeans and are a type of phytoestrogen. Phytoestrogens have the ability to interact with estrogen receptors in your body. They can either stimulate or inhibit the effects of estrogen.

Estrogen is widely known as the female sex hormone but is present in smaller amounts in men as well.

Phytoestrogens can also act as antioxidants. Antioxidants combat the harmful effects of free radicals, or molecules that are produced by processes in your body that create energy for your cells.

Although free radicals are created by the body, they can cause inflammation in the body and speed up the aging process.

Genistein and Daidzein are two notable types of isoflavones found in soybeans.

After soy is eaten, daidzein in particular is converted to a compound called equol. Equol is thought to be responsible for many of the potentially-positive health effects of soy.

The catch is that not everyone can convert daidzein to equol. This ability is most commonly seen in Asian populations as well as in vegetarians and vegans.

Soy And GMO Concerns

Approximately 90% of soybeans grown in the U.S. are GMOs, or genetically modified organisms.

Genetic modification of foods began with the dawn of agriculture. Seeds from plants that were naturally hardier and more resistant to disease were saved and over time, this lead to better crops.

Today we use gene splicing and other microscopic technologies to create better crops, and this has many people concerned. Regardless of the hype around genetic modification, GMO foods themselves are probably not of much concern.

What can be harmful, however, are the pesticides used on GMO crops. Roundup, which contains the pesticide Glyphosate, is found in small amounts on produce found in grocery stores. It contaminates the air, water, and soil and can lead to antibiotic resistance.

Glyphosate is being widely studied to see if it is harmful to humans when ingested.

Soy Allergies

Soy is one of the top 8 most common allergens.

An allergy to soy is most often diagnosed in infancy when soy formula is used. Children usually outgrow their soy allergy by the time they reach adulthood, but some people deal with soy allergies for life. Adult onset of a soy allergy is extremely uncommon.

Glycinin and Conglycinin are the main proteins in soy and are responsible for allergic reactions in sensitive individuals. Mild symptoms of a reaction include a tingling mouth, hives, itching, and flushing.

Serious soy allergies are rarely seen but are more common in people who have asthma or multiple other food allergies. The main symptom of a severe allergy is anaphylaxis, which is characterized by swelling of the face, low blood pressure, and trouble breathing.

Soy And Fertility

Soybeans may reduce your ability to conceive if eaten in high amounts.

One study showed that women who ate large amounts of soy experience changes in their ovulatory cycle. The hormones that control a woman’s ovulation and menstrual cycle are tightly regulated, and the phytoestrogens in soybeans can possibly reduce ovarian function. This can make it harder to conceive.

Another study showed that men who had diets high in soy experienced a lower sperm count than men who ate little to no soy. Lower sperm counts are linked to lower rates of conception.

Is Soy Safe During Pregnancy?

The isoflavones in soy are able to cross through the placenta and be absorbed by the infant. Little research has been done on whether this is a good or bad thing for pregnant mothers and their babies.

Soy Infant Formula Effects And Dangers

Many years ago, formula was seen as the gold standard in infant nutrition. Today we know that breastmilk is the perfect food for newborn babies and is custom made by each mom’s body for her infant’s needs.

However, not every mother is able to or wants to breastfeed, so soy formula is often used as a replacement for breastmilk.

The use of soy in infant formula is controversial because of the potential problems phytoestrogens may cause in babies.

Some studies have shown that subtle changes occur in the reproductive organs of infants fed soy formula. More research is still needed to see if these effects continue to be seen as the babies grow older.

Does Soy Work As A Menopause Treatment

The phytoestrogens in soy have become a popular treatment option for women experiencing unpleasant menopausal symptoms. These symptoms can include hot flashes, mood swings, and insomnia.

Studies regarding soy for the treatment of menopause are mixed. Some show that it is effectivee while others say the opposite.

Soy supplements or tablets are not recommended as good treatment options for women going through menopause. Only whole, minimally-processed soy foods like edamame or tofu are recommended.

Does Soy Cause Breast Cancer

The link between soy and breast cancer is another hotly debated topic.

Soy can affect everyone differently – in some it seems to prevent breast cancer, but in others it appears to contribute to it.

Some studies show that a diet that has consistently contained soy from adolescence can have a preventative effect against the formation of breast cancer.

Studies have also shown that women in remission who eat soy may have a reduced risk of recurrence.

On the other hand, some studies show that frequent consumption of concentrated soy protein can stimulate the growth of breast tumors.

Soy And Osteoporosis

The consumption of soybeans seems to be correlated with higher bone density in women. Although it is not understood why, adding minimally-processed soy foods to your diet seems to have a protective effect on bone.

A correlation between two things does not necessarily mean one causes the other. Correlation simply means that two factors, such as soy and bone health, were seen appearing together.

Causation means that one factor has been proven to cause another, such as the consumption of calcium in childhood resulting in healthy bones.

Effects Of Soy On Heart Health

Soybeans have carried the “Heart Healthy” claim for quite some time. However, in late 2017, the FDA decided to revoke this claim.

Soy itself has not been shown to provide any heart health benefits.

The benefits come from the fact that many people replace a diet high in animal protein with a diet containing soy. This simply reduces the amount of saturated animal fat that is consumed, which reduces the risk of heart disease.

So while soy itself does little to benefit your heart, incorporating some soy as well as fruits and vegetables into your diet (while cutting back on animal protein) can have many benefits to your overall health.

Can Soy Cause Memory Loss?

Few studies have been done on soy’s effects on memory.

One team of researchers found that soy may be linked to improvements in memory and cognition, but no other studies have proven this to be true.

Other studies show that too much soy can lead to a decline in memory and cognition. While this sounds concerning, the researchers thought this was actually due to a B12 deficiency, not the soy.

People who eat high amounts of soy tend to eat diets containing little or no animal products. Vitamin B12 is found only in animal products, and low levels of this vitamin can cause memory problems.

Is Soy Harmful To The Thyroid?

Some sources say that soy acts as a goitrogen. Goitrogens are substances that interfere with the production of thyroid hormones. They do this by preventing the absorption of iodine.

Regardless of this, there is currently no solid evidence proving that people with hypothyroidism need to avoid soy completely. Unless you already have an iodine deficiency, soy is not likely to cause any problems.

One thing to note is that people taking thyroid medications should not eat soy within four hours of taking their medication. This is due to soy’s tendency to decrease the absorption of certain medications.

Why Can’t We Decide if Soy is Good or Bad?

Soy is a controversial topic in the fields of science and nutrition. Some people believe soy to be a superfood capable of preventing and curing a wide array of diseases. Others believe soy to be a hormone disrupter that can lead to unwanted side effects.

The fact is that the science goes both ways. This is because soy is an interesting food that does not have the same effect on everyone.

How soy acts in your body depends on many factors, such as your age, sex, ethnicity, genes, and health-status. For instance, equol-producers are more likely to experience health benefits from soy. As mentioned above, these individuals can turn the isoflavone daidzein into equol, which in turn can have many positive effects in the body.

The form of soy that you’re eating also plays a big role. Minimally-processed soy foods like tofu, tempeh, and edamame are thought to be much healthier than highly-processed foods like soybean oil and soy protein isolate.

This is because the entire soybean is used in these minimally-processed foods. You get all of the nutrients that are naturally packaged within the soybean, rather than a refined or isolated product stripped of its vitamins, minerals, and antioxidants.

Although we tend to want definitive answers, the bottom line is that soy is a complicated little bean. It is neither good nor bad – its effects simply vary from person to person and product to product.

Takeaway Notes

  • The soybean has been eaten for thousands of years and was first grown in ancient East Asia.
  • Soybeans are used to make a dizzying number of products, from food, to fuel, to candle wax.
  • The only plant source of complete protein, soy is also high in fiber, good fats, vitamins, and minerals
  • Much of the health effects from soy are a result of phytochemicals, specifically isoflavones,that act similarly to estrogen in the body.
  • Soy has been studied for its role in many diseases and conditions, but results are mixed.
  • How your body reacts to soy depends on many factors like your health, age, sex, and genes.
Kelli Yates
Kelli Yates
Kelli Yates is a health and nutrition writer, dietetics student, and co-host and creator of The Nutrition Nerds Podcast. In her spare time she teaches the free class Well-Fed Survival: Eating Healthy After A Disaster, which helps people build nutritious emergency food supplies and prepare for natural disasters.
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