Is Soy Sauce Vegan? Is it Healthy? A Dietitian Explains

Served as a flavorful condiment and often used in various sauces and marinades, soy sauce is a versatile ingredient used in cuisines around the world. 

It’s also a common ingredient in vegan recipes. Since soy sauce is so popular, it’s important for vegans to know whether soy sauce is vegan-friendly. 

Additionally, there are many misconceptions about whether soy sauce, or soy in general, is safe to consume.

Read on for my take on soy sauce and how best to incorporate it into your diet!

What is soy sauce?

Soy sauce is a salty, umami condiment made from fermented soybeans. It is a very popular ingredient in Japanese, Chinese, Korean, Vietnamese, Indonesian, and Filipino cuisines, to name a few.

Most soy sauce used in the United States is the familiar dark brown sauce served with sushi, but many different types of soy sauce exist which vary in color, flavor, and consistency.

How is soy sauce made?

Soy sauce is traditionally made¹ by boiling soybeans, adding wheat, salt, and water, and fermenting them over a period of months with the help of a mold that also adds to the color, flavor, and aroma of the finished product. The fermentation process and resulting lactic acid also contribute to the flavor.

The soy sauce is then heated² to kill any remaining bacteria and microorganisms.

Is soy sauce vegan?

Yes, soy sauce is vegan! As explained above, soy sauce ingredients are plant based and usually only include soybeans, wheat, salt, and water. There are no animal products used in the production of soy sauce.

As a caveat, some specialty soy sauces use the flavor enhancers disodium 5′-inosinate and disodium 5′-guanylate, which can be produced from either vegan or non-vegan sources. According to the Vegetarian Resource Group³, however, it’s likely that these ingredients are vegan-friendly. Of course, if you want to be sure, it’s best to check with the manufacturer.

Sweeter varieties of soy sauce, such as dark soy sauce, can include sugar, which may or may not be vegan. Unfortunately, cane sugar is often processed with animal bone char in the United States. Organic sugar isn’t processed with bone char, so organic sweet soy sauces should be vegan friendly.

Some brands, like Kikkoman, Lee Kum Kee, and ABC, specifically state that their sweet soy sauces are vegan.

I thought soy was unhealthy – is this true?

Soy may be one of the most misunderstood and feared foods in the Western world. Fears about soy are largely unfounded – in fact, soy foods have most commonly been associated with health benefits! 

A major reason for concerns regarding the healthfulness and safety of consuming soy is its phytoestrogen content. Phytoestrogens, also called isoflavones, are commonly confused with the estrogen produced by humans and animals. While similar in structure to mammalian estrogen, phytoestrogens do not always act the same way in the body. 

In fact, depending on the area of the body, phytoestrogens can either have estrogenic or anti-estrogenic effects. The ability of phytoestrogens to block estrogen in reproductive tissues like the breast and uterus may at least partially explain the association between soy foods and decreased risk of cancer⁴ in these areas.

What about processed soy, as in soy sauce?

The available research does not support the idea that processed soy products are harmful. While whole or minimally processed soy foods such as edamame, tempeh, tofu, and soy milk contain more vitamins, minerals, and isoflavones, this does not mean that foods containing soy which has been more processed are inherently unhealthy.

Health risks 

Sodium content

Soy sauce can be extremely high in sodium, making it a concern for individuals with high blood pressure or congestive heart failure. Kikkoman soy sauce contains 960 milligrams of sodium in 1 tablespoon (almost 50% of the daily value)! 

Even for people without these health issues, it’s recommended to consume less than 2300 milligrams of sodium every day.

Fortunately, “less sodium” versions are available. Keep in mind that while these versions have less sodium than their counterparts, they aren’t considered to be “low sodium”. 

What’s the difference? “Low sodium” is a nutrient content claim regulated by the FDA⁵, which requires any product labeled as such to have less than 140 milligrams of sodium per serving. The “less sodium” varieties have more than 140 milligrams of sodium, but less than regular soy sauce does.

Gluten

It may seem like soy sauce would be gluten-free, but this is not the case. As we saw previously, wheat is added during the production of soy sauce to aid in fermentation. Therefore, soy sauce should be avoided by people with Celiac disease or non-Celiac gluten sensitivity⁶.

Fortunately, there are a couple gluten-free alternatives to soy sauce. Tamari is a soy-based sauce similar to soy sauce, but does not contain gluten. This makes it a great gluten-free soy sauce alternative.

Coconut aminos is another gluten-free alternative to soy sauce. This condiment is made by fermenting coconut tree sap and is soy-free.

Migraines

Soy sauce may trigger migraines in some people. This is because fermented soy foods, such as soy sauce, tamari, tempeh, and natto, are higher in a natural compound called tyramine. When foods containing the amino acid tyrosine are fermented, tyrosine is broken down into tyramine.

Monosodium glutamate (MSG) is another compound that occurs naturally during the process of making soy sauce. MSG has often been regarded as a health hazard, despite the lack of scientific evidence for these claims. Some people believe that MSG also causes migraines.

However, the evidence⁷ on this is unclear. It’s possible that people who develop migraines after eating soy sauce and attribute it to MSG may actually be reacting to tyramine instead.

If you notice that MSG is a migraine trigger for you, coconut aminos may be a good alternative to soy sauce as it is MSG-free. However, coconut aminos likely contains tyramine since it is a fermented product.

Genetic engineering

Most soy grown in the US is genetically engineered to be resistant to the herbicide glyphosate, and many varieties of soy sauce on the market are made from genetically engineered soybeans. While genetically engineered foods are tested for safety before being approved for use in the food supply, studies on the long-term health effects of these foods are lacking. 

If you wish to avoid soy sauce made from genetically engineered soy, you can choose an organic variety.

Foods with the USDA Organic label are prohibited from being genetically engineered. There are also some non-organic soy sauce brands that specifically state on the label that they do not contain bioengineered ingredients, one of which being the Kikkoman⁸ brand.

Glyphosate

Glyphosate (Roundup) is a weed killer frequently sprayed on soybeans which have been genetically engineered to survive being exposed to this pesticide. 

Concerns about the health risks of glyphosate are common, but expert opinions on whether it poses a risk to human health are conflicting. For example, the Environmental Protection Agency states that glyphosate⁹ is not carcinogenic, while the World Health Organization International Agency for Research on Cancer¹⁰ believes it is probably carcinogenic. Overall, high quality research¹¹ on the potential impacts of glyphosate residues on human health is lacking.

Because of this, it is understandable that some people prefer to avoid eating crops sprayed with glyphosate. To avoid soy sauce made from soybeans sprayed with glyphosate, you can purchase organic or non-genetically engineered varieties.

Soy allergies

Lastly and unsurprisingly, soy sauce should be avoided by people who are allergic to soy. Coconut aminos are a good alternative for people with soy allergies.

How to choose the best soy sauce

1. Look for “less sodium” or “reduced sodium” varieties. These will drastically cut down on the sodium content, while still being flavorful enough to use in sauces and marinades. 
2. If choosing to avoid glyphosate or genetically engineered soy, buy organic. USDA-certified organic foods are not allowed to contain genetically engineered ingredients, which includes soybeans engineered to be resistant to glyphosate.
3. For a gluten-free alternative: try tamari or coconut aminos 
4. For a soy-free, gluten-free alternative: try coconut aminos

Using soy sauce in vegan dishes

Soy sauce is an amazing ingredient for adding flavor and a boost of umami to vegan dishes, which often require a lot of seasoning. Try using soy sauce in the following ways:

• Add to marinades for tempeh, tofu, seitan, and other plant-based proteins.
• Drizzle a small amount over sauteed vegetables
• Add to tomato-based pasta sauces 
• Use in stir-fry sauces
• Add to vegan chili
• Use as a condiment for vegan sushi
• In veggie fried rice
• Use in a savory peanut sauce for Buddha bowls, sweet potatoes, or spring rolls
• Add to brothy soups

Remember, add soy sauce to dishes BEFORE adding salt – it’s easy to underestimate how salty even lower-sodium soy sauce can be!

Summary

Soy sauce is a versatile, flavorful condiment used in a variety of cuisines around the world. Soy sauce is considered vegan-friendly since it is traditionally made by fermenting soybeans, wheat, water, and salt. There are no animal products used in the production of soy sauce.

Health concerns about soy are largely unsupported by current scientific evidence, although long-term safety information on glyphosate and genetically engineered crops is lacking. If you prefer to reduce your exposure to soybeans that have been sprayed with glyphosate or genetically engineered, choose organic or non-bioengineered soy sauce.

Choosing “less sodium” or “reduced sodium” varieties will dramatically reduce the sodium content while still being flavorful enough for cooking. Tamari is a gluten-free alternative to soy sauce, while coconut aminos is another alternative which is free from both gluten and soy.

References

1. Miyajima Shoyu Co. Soy Sauce Production Process. https://www.miyajima-soy.co.jp/english-site/en-fermented-foods/about-soy-sauce. Accessed September 1, 2022.
2. Kikkoman Corporation. Making Soy Sauce. https://www.kikkoman.com/en/shokuiku/soysaucemuseum/making/index_en.html. Accessed September 1, 2022.
3. Yacoubou, Jeanne. Disodium inosinate and disodium guanylate are all-vegetable flavor enhancers. The Vegetarian Resource Group Blog. https://www.vrg.org/blog/2011/03/21/disodium-inosinate-and-disodium-guanylate-are-all-vegetable-flavor-enhancers/. Accessed September 1, 2022.
4. Pabich M, Materska M. Biological Effect of Soy Isoflavones in the Prevention of Civilization Diseases. Nutrients. 2019 Jul 20;11(7):1660. doi: 10.3390/nu11071660. PMID: 31330799; PMCID: PMC6683102.
5. U.S. Food & Drug Administration. CFR – Code of Federal Regulations Title 21. https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=101.61. Accessed September 1, 2022.
6. Celiac Disease Foundation. Non-Celiac Gluten/Wheat Sensitivity. https://celiac.org/about-celiac-disease/related-conditions/non-celiac-wheat-gluten-sensitivity/. Accessed September 1, 2022.
7. Obayashi Y, Nagamura Y. Does monosodium glutamate really cause headache? : a systematic review of human studies. J Headache Pain. 2016;17:54. doi: 10.1186/s10194-016-0639-4. Epub 2016 May 17. PMID: 27189588; PMCID: PMC4870486.
8. Kikkoman Corporation. Kikkoman Soy Sauce: Guaranteed GMO-free! Accessed September 1, 2022.
9. United States Environmental Protection Agency. Glyphosate. https://www.epa.gov/ingredients-used-pesticide-products/glyphosate. Accessed September 1, 2022.
10. Guyton KZ, Loomis D, Grosse Y, El Ghissassi F, Benbrahim-Tallaa L, Guha N, Scoccianti C, Mattock H, Straif K; International Agency for Research on Cancer Monograph Working Group, IARC, Lyon, France. Carcinogenicity of tetrachlorvinphos, parathion, malathion, diazinon, and glyphosate. Lancet Oncol. 2015 May;16(5):490-1. doi: 10.1016/S1470-2045(15)70134-8. Epub 2015 Mar 20. PMID: 25801782.
11. Cuhra, Marek. (2015). Review of GMO safety assessment studies: glyphosate residues in Roundup Ready crops is an ignored issue. environmental sciences europe. 27. 1-14. 10.1186/s12302-015-0052-7.