Does Kikkoman Soy Sauce Have Iodine?

December 19, 2025 •

3 min read

According to nutritional data, Kikkoman Naturally Brewed Soy Sauce contains 0 µg of iodine per serving, making it essentially iodine-free. This fact is crucial for individuals monitoring their iodine intake, especially those on a low-iodine diet for health reasons, such as preparing for thyroid-related medical procedures.

Quick Summary

Kikkoman soy sauce, brewed from water, soybeans, wheat, and salt, contains no detectable iodine based on nutrition labels. The potential for iodine contamination depends on the type of salt used during production, with iodized salt or kelp additives being primary sources, which Kikkoman avoids. This makes the product a suitable option for those on a low-iodine diet, provided no kelp-based products are added.

Key Points

No Detectable Iodine: Kikkoman Naturally Brewed Soy Sauce contains 0 µg of iodine per serving, based on nutritional information.
Limited Ingredients: The standard recipe includes only water, soybeans, wheat, and salt, with no artificial additives or iodine-rich kelp.
Salt Type is Key: Kikkoman uses non-iodized salt, unlike some other brands that may use iodized salt, a potential source of iodine.
Important for Low-Iodine Diets: Due to its lack of iodine, Kikkoman is a suitable condiment for individuals adhering to a low-iodine dietary protocol.
Check Labels for Additives: Always check the ingredient list of other soy sauces, as some may contain kelp or other iodine-rich additives not found in standard Kikkoman products.

Kikkoman's Ingredients and Natural Brewing Process

Kikkoman's standard naturally brewed soy sauce is made with just four primary ingredients: water, soybeans, wheat, and salt. The company explicitly states that it uses no artificial additives, colors, or preservatives. This adherence to a traditional, centuries-old fermentation process is key to understanding its nutritional profile, including its iodine content. The fermentation process itself does not introduce iodine into the product. During this process, specific microorganisms act on the soybeans and wheat, which contain no inherent iodine, to create the rich, umami flavor.

The Source of Iodine in Other Soy Sauces

While Kikkoman's core product is iodine-free, it's important to understand where iodine might be found in other soy sauces. The most common sources are the addition of kelp extract or the use of iodized salt. Some specialty soy sauces, particularly those with a seaweed base, may contain significant levels of iodine. This is because seaweed, like kelp, is extremely rich in the mineral, with some types containing over 2,000% of the daily recommended intake in a single gram. However, since Kikkoman does not use these additives, its iodine content remains undetectable.

The Role of Salt in Soy Sauce Production

The type of salt used in food production is a major factor influencing iodine content. Iodized salt is table salt to which potassium iodide or potassium iodate has been added to prevent iodine deficiency. Most processed foods in regions with Universal Salt Iodization (USI) programs will have higher iodine levels as a result. However, many soy sauce manufacturers, including Kikkoman, rely on non-iodized salt for their brewing process. A study analyzing Taiwanese soy sauces found that most were iodine-free, with the few that contained iodine either having kelp extract or a much higher salt content, suggesting the use of iodized salt. Kikkoman's commitment to its four core ingredients and natural brewing method prevents the inclusion of these iodine-rich additives.

Reading Labels and Avoiding Hidden Iodine

For those on a strict low-iodine diet, knowing what to look for on a product label is essential. The ingredient list is the most reliable source of information. A standard Kikkoman label will clearly list only water, soybeans, wheat, and salt. If a different brand or specialty soy sauce lists any form of seaweed (like kombu or kelp extract) or a type of salt that is not specified as non-iodized, it is best to avoid it. The nutritional information panel may also explicitly list iodine content, though this is not universally required.

Kikkoman vs. Other Soy Sauce Types

Comparison Table: Iodine Content in Sauces


Sauce Type	Primary Ingredients	Iodine Potential	Notes
Kikkoman Soy Sauce	Water, Soybeans, Wheat, Salt	None detected (0 µg)	Brewed naturally with no additives.
Some Taiwanese Soy Sauces	Varies, may contain kelp extract	High in some varieties	A study found a few brands with high iodine from kelp or iodized salt.
Soy Sauce with Kelp	Soybeans, wheat, salt + kelp	Very High (from kelp)	Specifically includes seaweed, a high-iodine ingredient.
Fish Sauce	Fish, salt, water	Medium-to-High	Derived from seafood, which is a natural source of iodine.
Salsa & Dips (with iodized salt)	Varies widely	Low-to-Medium	Depends entirely on whether iodized or non-iodized salt is used.

Conclusion: Kikkoman and Your Low-Iodine Diet

In conclusion, for those seeking to minimize their dietary iodine, Kikkoman Naturally Brewed Soy Sauce is a safe choice. Its transparent ingredient list of only water, soybeans, wheat, and salt confirms that no iodine-containing additives, such as kelp or iodized salt, are used in its production. This makes it a valuable seasoning option for individuals following a low-iodine diet for thyroid health or other medical reasons. As always, reviewing the ingredient list of any food product is the best way to ensure it meets specific dietary requirements. For further information on the role of iodine in diet and nutrition, consulting reputable health and nutrition websites can be beneficial.

Frequently Asked Questions

Yes, standard Kikkoman Naturally Brewed Soy Sauce is considered safe for a low-iodine diet because its ingredients do not include sources of iodine, and its nutrition label indicates 0 µg of iodine.

Other brands of soy sauce might contain iodine if they use iodized salt or add iodine-rich ingredients like kelp extract during production. Kikkoman avoids these additives.

While the standard soy sauce is iodine-free, other Kikkoman products, especially specialty sauces, might contain ingredients that introduce iodine. Always check the specific product's ingredient list and nutrition label.

No, soybeans themselves do not contain significant levels of iodine. The iodine content in soy products primarily comes from additives like iodized salt or kelp during processing.

To be certain, always read the ingredient list to ensure there is no mention of kelp, seaweed, or other marine-based additives. Additionally, look for brands that specify the use of non-iodized salt.

The iodine content in both regular and less-salt Kikkoman soy sauce is undetectable, as neither recipe uses iodine-containing ingredients.

Common sources of iodine in processed foods include iodized salt, dairy products, eggs, and food additives like kelp extract.