Each type of soy sauce varies due to “fermentation times, temperatures, and ratios of ingredients,” according to the Journal of Agricultural and Food Chemistry study, and comes with different flavors. The same article noted that the method of choice for producing soy sauce also varies according to the country of origin. Still, it’s traditionally prepared with soybeans, wheat, salt, water, and fermenting agents (mold or yeast). The mixture is left to ferment for eight months or more; then, it is pasteurized before it’s bottled.
How Is Soy Sauce Made and Is It Bad for You?
Soy sauce is a very flavorful ingredient made from fermented soybeans and wheat.
It originated in China and has been used in cooking for over 1,000 years.
Today, it’s one of the best-known soy products worldwide. It is a staple ingredient in many Asian countries and used widely across the rest of the world.
The way it’s produced can vary significantly, causing significant changes in flavor and texture, as well as health risks.
This article investigates how soy sauce is produced and its potential health risks and benefits.
Soy sauce is a salty liquid condiment traditionally produced by fermenting soybeans and wheat.
It is thought to have originated from a Chinese product called “chiang” over 3,000 years ago. Similar products were developed in Japan, Korea, Indonesia and across Southeast Asia.
It first came to Europe in the 1600s through Dutch and Japanese trading (1, 2).
The word “soy” comes from the Japanese word for soy sauce, “shoyu.” In fact, the soybean itself was named from soy sauce (1).
The four basic ingredients in soy sauce are soybeans, wheat, salt and fermenting agents like mold or yeast.
Regional varieties of soy sauce may have varying amounts of these ingredients, resulting in different colors and flavors.
Summary Soy sauce is a salty
condiment produced through the fermentation of soybeans and wheat. It
originated in China and is now produced in many Asian countries.
Many different types of soy sauce are available. They can be grouped based on their production methods, regional variations, color and taste differences.
Traditional Production
Traditional soy sauce is made by soaking soybeans in water and roasting and crushing the wheat. Then the soybeans and wheat are mixed with a culturing mold, most commonly Aspergillus, and left for two to three days to develop.
Next, water and salt are added, and the entire mixture is left in a fermenting tank for five to eight months, though some types may age longer.
During fermentation, enzymes from the mold act on the soy and wheat proteins, gradually breaking them down into amino acids. The starches are converted to simple sugars, then fermented to lactic acid and alcohol.
After the aging process is complete, the mixture is laid out onto cloth and pressed to release the liquid. This liquid is then pasteurized to kill any bacteria. Finally, it’s bottled (3, 4).
High-quality soy sauce uses only natural fermentation. These varieties are often labeled “naturally brewed.” The ingredients list will usually only contain water, wheat, soy and salt.
Summary Traditional soy sauce
is made with a mixture of soybeans, roasted wheat, mold and salt water, which
is aged for five to eight months. The resulting mash is then pressed, and the
soy sauce liquid is pasteurized and bottled.
Chemical production
Chemical production is a much faster and cheaper method of making soy sauce. This method is known as acid hydrolysis, and it can produce soy sauce in a few days instead of many months .
In this process, soybeans are heated to 176°F (80°C) and mixed with hydrochloric acid. This process breaks down the proteins in the soybeans and wheat.
However, the resulting product is less attractive in terms of taste and aroma, since many substances produced during traditional fermentation are missing. Therefore, extra color, flavor and salt are added (4).
Additionally, this process produces some undesirable compounds that are not present in naturally fermented soy sauce, including some carcinogens (2).
In Japan, soy sauce that is brewed in a purely chemical process is not considered soy sauce and cannot be labeled as such. However, it may be mixed with traditional soy sauce to lower costs.
In other countries, chemically produced soy sauce may be sold as-is. This is often the type of soy sauce you’ll find in the small packets given with take-away meals.
The label will list “hydrolyzed soy protein” or “hydrolyzed vegetable protein” if it contains chemically produced soy sauce.
Summary Chemically
manufactured soy sauce is made by hydrolyzing soy proteins with acid and heat.
This method is quick and cheap, but the resulting soy sauce tastes inferior,
contains some toxic compounds and may require extra colors and flavors.
Regional Differences
In Japan there are many different types of soy sauce.
- Dark soy sauce: Also known as
“koikuchi shoyu,” this is the most common type sold in Japan and overseas.
It’s reddish brown and has a strong aroma (2, 3, 5 ). - Light soy sauce: Also called “usukuchi,” this is made from more soybeans and less
wheat, and it has a lighter appearance and milder aroma (2, 3, 5 ). - Tamari: Made from mostly soybeans with 10%
or less wheat, it lacks aroma and is darker in color (3, 5 ). - Shiro: Made almost only with wheat and very few soybeans, it’s very light in color (3).
- Saishikomi: Made by breaking down the soybeans and wheat with
enzymes in a solution of unheated soy sauce instead of salt water. It has
a heavier taste, and many enjoy it as a dipping sauce (2, 3, 5 ).
In China, the tamari-style soybean-only soy sauce is the most common type.
However, today a more modern production method is most common. Soybean meal and wheat bran are fermented for just three weeks instead of several months. This method results in a very different flavor compared to traditionally produced soy sauce (2, 3, 6).
Chinese soy sauces are often listed as “dark” or “light” in English. Dark soy sauce is thicker, older and sweeter and used in cooking. Light soy sauce is thinner, younger and saltier, and it’s more often used in dipping sauces.
In Korea, the most common type of soy sauce is similar to the dark koikuchi type in Japan.
However, there is also a traditional Korean soy sauce called hansik ganjang. It’s made only from soybeans and mainly used in soup and vegetable dishes (3).
In Southeast Asian countries like Indonesia, Malaysia, the Philippines, Singapore and Thailand, the tamari-style sauce is most commonly produced, but many local variations exist (2).
Other varieties include sauces thickened with sugar, such as kecap manis in Indonesia, or those with additional flavors added, such as shrimp soy sauce in China.
Summary There is a great
variety of soy sauces across Asia, each with different ingredients, flavors and
aromas. The most common type is Japanese dark soy, called koikuchi shoyu, which
is made from naturally fermented wheat and soybeans.
Below is the nutritional breakdown for 1 tablespoon (15 ml) of traditionally fermented soy sauce (7).
This makes it high in salt, providing 38% of the Recommended Daily Intake (RDI). While soy sauce has a relatively high amount of protein and carbohydrates by volume, it’s not a significant source of those nutrients.
In addition, the fermentation, aging and pasteurization processes result in a highly complex mix of more than 300 substances that contribute to the aroma, flavor and color of soy sauce.
These include alcohols, sugars, amino acids like glutamic acid, as well as organic acids like lactic acid.
The amounts of these substances change significantly depending on the base ingredients, the strain of mold and the method of production (3, 4).
It is these compounds in soy sauce that are often linked with its health risks and benefits.
Summary Soy sauce is high in
salt, providing 38% of the RDI in 1 tablespoon. It contains more than 300
compounds that contribute to flavor and aroma. These compounds may also be
associated with health risks and benefits.
Health concerns are often raised regarding soy sauce, including its salt content, presence of cancer-causing compounds and specific reactions to components like MSG and amines.
It Is High in Sodium
Soy sauce is high in sodium, commonly known as salt, which is an essential nutrient that your body requires to function properly.
However, high intakes of sodium are linked to increased blood pressure, especially in salt-sensitive people, and may contribute to the risk of heart disease and other diseases such as stomach cancer ( 8 , 9, 10, 11).
In fact, reducing your sodium intake results in a modest decrease in blood pressure and can be part of a treatment strategy for people with high blood pressure ( 12 , 13 , 14 , 15 ).
However, it is not clear if reduction directly lowers the incidence of heart disease in healthy people ( 13 , 16 , 17 , 18).
Most dietary organizations recommend an intake of 1,500–2,300 mg of sodium per day, with the aim of reducing the risk of high blood pressure ( 12 , 19 , 20, 21).
One tablespoon of soy sauce contributes 38% of the current RDI. However, the same amount of table salt would contribute 291% of the RDI for sodium (7, 22).
For those looking to reduce their sodium intake, salt-reduced varieties of soy sauce, which contain up to 50% less salt than the original products, have been developed (2).
Despite its high sodium content, soy sauce can still be enjoyed as part of a healthy diet, especially if you are limiting processed food and mostly consuming fresh, whole foods with plenty of fruits and vegetables.
If you are limiting your salt intake, try a salt-reduced variety or simply use less.
Summary Soy sauce is high in
sodium, which is associated with an increased risk of high blood pressure.
However, it is lower in sodium than table salt, and sodium-reduced varieties
are available. Soy sauce can be included as part of a healthy diet rich in
whole foods.
Can Be High in MSG
Monosodium glutamate (MSG) is a flavor enhancer. It’s found naturally in some foods and often used as a food additive (23).
It is a form of glutamic acid, an amino acid that contributes significantly to the umami flavor of foods. Umami is one of the five basic flavors in food, often found in what is called “savory” food ( 24 , 25 ).
Glutamic acid is produced naturally in soy sauce during fermentation and thought to be a significant contributor to its appealing flavor. Additionally, MSG is often added to chemically produced soy sauce to enhance its flavor (2, 5 , 26 , 27 ).
In 1968, MSG became associated with a phenomenon known as MSG symptom complex.
Symptoms included headaches, numbness, weakness and heart palpitations after eating Chinese food, which is often high in MSG (23, 24 ).
However, a 2015 review of all studies to date on MSG and headaches did not find significant evidence to suggest that MSG causes headaches (23, 24 , 28 ).
Therefore, the presence of glutamic acid or even added MSG in soy sauce is probably no cause for concern.
Summary MSG and its free form,
glutamic acid, are an important part of the appealing umami taste of soy sauce.
Although MSG was once thought to cause headaches, recent reviews suggest this isn’t the case.
May Contain Cancer-Causing Substances
A group of toxic substances called chloropropanols can be produced during food processing, including the production of soy sauce.
One type, known as 3-MCPD, is found in acid-hydrolyzed vegetable protein, which is the type of protein found in chemically produced soy sauce (29, 30 ).
Animal studies have found 3-MCPD to be a toxic substance. It was found to damage the kidneys, decrease fertility and cause tumors (29, 30 ).
Due to these problems, the European Union set a limit of 0.02 mg of 3-MCPD per kg (2.2 lbs) of soy sauce. In the US, the limit is higher at 1 mg per kg (2.2 lbs) ( 30 , 31, 32).
This equates to a legal limit of 0.032–1.6 mcg per tablespoon of soy sauce, depending on where you live.
However, in recent years, investigations of soy sauce imports across the world, including in the US, UK, Australia and Europe, have found products significantly over the limits, with up to 1.4 mg per tablespoon (876 mg per kg), resulting in product recalls ( 30 , 31, 33).
Overall, it is safer to choose naturally fermented soy sauce, which has much lower levels or no 3-MCPD at all.
Summary Chemically produced soy
sauce contains a toxic substance called 3-MCPD. Across the globe, there have
been multiple recalls of soy sauce products that exceed safe limits of the
substance. It’s best to stick to naturally fermented soy sauce.
Contains Amines
Amines are naturally occurring chemicals found in plants and animals.
They are often found in higher concentrations in aged foods, such as meats, fish, cheeses and some condiments (34).
Soy sauce contains significant amounts of amines, including histamine and tyramine (3, 35).
Too much histamine is known to cause toxic effects when eaten in high quantities. Symptoms include headaches, sweating, dizziness, itching, rashes, stomach problems and changes in blood pressure (34, 36 ).
In fact, it has been suggested that some reports of soy sauce allergy may be due to a histamine reaction ( 37 ).
In most people, the other amines in soy sauce don’t appear to cause problems. However, some people can be sensitive to them. This is usually diagnosed through a supervised elimination diet. Symptoms of intolerance include nausea, headaches and rashes (34).
If you are sensitive to amines and experience symptoms after eating soy sauce, it may be better to avoid it.
Additionally, people taking a class of medication known as monoamine oxidase inhibitors (MAOIs), need to restrict their tyramine intake and should avoid soy sauce ( 38 , 39 ).
Summary People who are sensitive
to amines, including histamine, may want to reduce their intake of soy sauce or
avoid it altogether. If you are taking an MAOI, you should avoid soy sauce due
to its tyramine content.
Contains Wheat and Gluten
Many people are unaware that soy sauce can contain both wheat and gluten. For people with wheat allergies or celiac disease, this could be problematic.
Studies have found that both soy and wheat allergens are completely degraded in the soy sauce fermentation process. That said, if you are not sure how your soy sauce has been produced, you cannot be sure it is free from allergens ( 40 ).
The Japanese soy sauce tamari is often regarded as a wheat- and gluten-free soy sauce alternative. While this can be true, some types of tamari may still be made with wheat, though with smaller amounts than are used in other types of soy sauce (3).
It is important to check the ingredients label for wheat and look for soy sauce products that are specifically labeled as gluten-free. Most major brands carry a gluten-free variety.
When you’re eating out, it’s best to double check what brand of soy sauce the restaurant is cooking with and ask if they have a gluten-free variety.
If you are unsure, it may be better to choose a dish not cooked with soy sauce.
Summary Soy sauce contains wheat
and gluten, and even the tamari type may still contain some wheat. If you are
allergic to wheat or have celiac disease, look for gluten-free soy sauce and
always check the ingredients list.
Soy Sauce: How It’s Made and How It Can Affect Your Health
Soy sauce is loaded with sodium, but the condiment could also have surprising benefits.
Cynthia Sass is a nutritionist and registered dietitian with master’s degrees in both nutrition science and public health. Frequently seen on national TV, she’s Health’s contributing nutrition editor and counsels clients one-on-one through her virtual private practice. Cynthia is board certified as a specialist in sports dietetics and has consulted for five professional sports teams, including five seasons with the New York Yankees. She is currently the nutrition consultant for UCLA’s Executive Health program. Sass is also a three-time New York Times best-selling author and Certified Plant Based Professional Cook. Connect with her on Instagram and Facebook, or visit www.CynthiaSass.com.
Updated on November 4, 2022
Medically reviewed by
Allison Herries, RDN, is a registered dietitian for a telehealth company. In her role, she provides nutrition education and counseling to help her clients set and reach their personal health goals.
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- Soy sauce is a fermented condiment often used in Asian cuisine.
- While soy sauce is high in sodium, it has some health benefits.
- You can try other options if you’re sensitive to histamine or want to reduce sodium in your diet.
Take a peek in most kitchen pantries or refrigerators and you’re likely to see an assortment of condiments—mustard, mayo, bar-b-que sauce, salad dressings, and soy sauce. Soy sauce is a popular condiment used in Asian cuisine. Though the sauce might not be healthy in all aspects of nutrition, it has been linked to some health benefits. Learn how soy sauce is made, how the condiment can affect your health, and some soy sauce alternatives you can use.
Per a September 2020 article published in the Journal of Agricultural and Food Chemistry, soy sauce usually has a salty, savory, umami taste; it is used when preparing cooked and uncooked foods.
Nutritional Values of Soy Sauce
The U.S. Department of Agriculture (USDA) says that a tablespoon of soy sauce (made from soy and wheat) contains:
How Soy Sauce Is Made
When you think of soy sauce, a dark-colored sauce usually comes to mind. However, several types of soy sauce exist, including:
- Light soy sauce
- Dark soy sauce
- Tamari soy sauce
- White soy sauce
- Sweet soy sauce
- Non-fermented soy sauce
Each type of soy sauce varies due to “fermentation times, temperatures, and ratios of ingredients,” according to the Journal of Agricultural and Food Chemistry study, and comes with different flavors. The same article noted that the method of choice for producing soy sauce also varies according to the country of origin. Still, it’s traditionally prepared with soybeans, wheat, salt, water, and fermenting agents (mold or yeast). The mixture is left to ferment for eight months or more; then, it is pasteurized before it’s bottled.
Quicker, cheaper methods of making soy sauce—which may be labeled as hydrolyzed soy protein—are generally more chemical-driven. Manufacturers may use additives to enhance color and flavor. Furthermore, some soy sauce products have been found to contain unwanted compounds, including known carcinogens.
According to a 2014 article published in Comprehensive Reviews in Food Science and Food Safety, some of these quicker methods can lead to the production of a chemical called 3-MCPD. This chemical has been tied to tumors, infertility, and kidney damage in animal studies, but there is little evidence about its effects on humans.
Salt vs. Sodium
Though having enough salt in your diet is important, eating too much of it can lead to health conditions like high blood pressure. While traditional soy sauce is low in calories and carbs—less than 10 calories and 1 gram of carbs per tablespoon—it has very high levels of sodium.
A single tablespoon contains over 900 milligrams of sodium. That is more than a third of the recommended daily limit for healthy adults which both the USDA and U.S. Department of Health and Human Services peg at 2300 milligrams.
If your body is sensitive to sodium, a sodium spike may trigger water retention, which can result in bloating or slight swelling around the hands and feet. You might notice indentations in your skin after you remove your socks or that your rings or watch fit a little snugger. And over time, having too much sodium can increase your risk for heart disease, according to the Centers for Disease Control and Prevention (CDC).
Health Benefits of Soy Sauce
Despite having a lot of salt and sodium, soy sauce could help protect your health. According to a 2019 Biotechnology Advances review, soy sauce can reduce immune responses, helping people who have pesky seasonal allergies.
Soy sauce may also be able to reduce the instance of IL-6—an inflammatory cytokine (a protein produced by cells related to or beyond the immune system), per an August 2022 study published in Microorganisms. Other studies also showed that dark soy sauce could be an antioxidant.
Besides soy sauce, other fermented soy products have also been linked to health benefits. For example, a 2019 Nutrients study found that tempeh could be linked to healthier gut microbiomes. Meanwhile, natto may be able to help prevent blood clots and high blood pressure. Overall, a 2019 article published in Food Chemistry found that fermented soy products showed promise in preventing inflammation, diabetes, and cancer. However, more research is needed.
Other Health Considerations
Soy sauce, like other fermented foods, also contains significant amounts of histamine. Your body releases histamines to aid in digestion. It’s also released in response to injury or allergies to increase inflammation, which can aggravate conditions like rosacea. Too much histamine can also trigger symptoms such as headaches, dizziness, itching, rashes, and digestive problems in those with histamine intolerance. Furthermore, if you’re sensitive or allergic to gluten, wheat, or soy, then you may want to avoid soy sauce.
Soy Sauce Alternatives
If you enjoy soy sauce and can tolerate it well, make sure to use naturally-brewed varieties, according to nutritionist Cynthia Sass, MPH. She recommended Kikoman’s Organic Soy Sauce. However, keep in mind that lite, reduced sodium, or less-sodium sauces can still be high in salt. Most still provide about 600 milligrams of sodium per tablespoon.
But if you are allergic to soy sauce or want a lower sodium alternative, you can also try coconut aminos. Sass recommended Bragg’s Coconut Liquid Amch is made with organic coconut blossom nectar, distilled organic apple cider vinegar, and sea salt. It’s both gluten- and soy-free. And, though the flavor is less intense than soy sauce, one tablespoon portion provides just 140 milligrams of sodium (6% of the recommended daily limit).
Coconut aminos can be used as a one-to-one substitute in any recipe or as a condiment, Sass said. One of the ways she recommended using coconut aminos is in a simple stir-fry sauce. To make the sauce, mix the aminos with some fresh-squeezed tangerine juice, freshly grated ginger root, minced garlic, and crushed red pepper. Then, sauté with a generous portion of veggies. Serve your stir-fry with a lean protein over a small scoop of brown or wild rice, and top with chopped nuts or pumpkin seeds.
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