How Bad Is Soy Sauce for You, Really?

You may have doused your sushi or Chinese food with soy sauce countless times. But have you given much thought to what's in that salty, dark liquid—and if soy sauce is any good for you? Here's a quick primer on the Asian condiment.

There are different ways to make soy sauce, but traditionally, it's prepared with soybeans, wheat, salt, and fermenting agents (mold or yeast). It’s then left to ferment for eight months or more; and 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. They may use additives to enhance color and flavor, and some soy sauce products have been found to contain unwanted compounds, including known carcinogens. One chemical detected in those products, called 3-MCPD, has been tied to tumors, infertility, and kidney damage in animal studies.

Soy sauce, like other fermented foods, also contains significant amounts of histamine, which can aggravate conditions like rosacea. Too much histamine can also trigger symptoms such as headaches, dizziness, itching, rashes, and digestive problems. If you’re sensitive or allergic to gluten, wheat, or soy, then soy sauce is totally off-limits.

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While traditional soy sauce is low in calories and carbs (with less than 10 calories and 1 gram of carbs per tablespoon), it’s incredibly high in sodium. A single tablespoon contains over 900 mg, which is more than a third of the maximum recommended daily limit for healthy adults (2300 mg). 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 you skin after you remove your socks, or that your rings or watch fit a little snugger.

The news isn’t all bad. Some research has shown that because it's fermented, soy sauce may help support the growth of beneficial bacteria in the digestive tract, including Lactobacillus bulgaricus, which may improve digestive health and immunity. Interestingly, soy sauce consumption has also been linked to helping people who suffer from seasonal allergies.

If you enjoy soy sauce and can tolerate it well, stick with naturally-brewed varieties, like Kikoman’s Organic Soy Sauce.

Just keep in mind that lite, reduced sodium, or less-sodium sauces can still be quite high in salt. Most still provide about 600 mg of sodium per tablespoon.

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The flavor is less intense than soy sauce, but I like Bragg’s Coconut Liquid Aminos, which is made with organic coconut blossom nectar, distilled water, organic apple cider vinegar, and sea salt. It's gluten- and soy-free, and all-natural. Plus a one tablespoon portion provides just 140 mg of sodium, or 6% of the recommended daily cap. It can be used as a one-to-one substitute in any recipe, or as a condiment.

One of my favorite ways to use coconut aminos is in a simple stir-fry sauce, mixed with a little fresh-squeezed tangerine juice, fresh grated ginger root, minced garlic, and crushed red pepper. Sauté with a generous portion of veggies, and serve with a lean protein over a small scoop of brown or wild rice, topped with chopped nuts or pumpkin seeds. Dinner, done!

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Cynthia Sass, MPH, RD, is Health's contributing nutrition editor, a New York Times best-selling author, and a private practice performance nutritionist who has consulted for five professional sports teams.