Is Miso High in MSG? A Deep Dive into Umami

November 15, 2025 •

2 min read

Over 1,200 types of miso exist in Japan, and a common question for health-conscious foodies is whether this umami-rich paste contains MSG. While traditional miso does not contain added MSG, it is naturally rich in glutamate, the amino acid that provides that savory flavor.

Quick Summary

Authentic miso does not have added MSG, but its deep umami flavor comes from naturally occurring free glutamate, released during fermentation. The presence of artificial MSG is typically found in cheaper, mass-produced instant versions, rather than traditional varieties.

Key Points

Naturally Occurring Glutamate: Authentic miso paste's umami flavor comes from naturally occurring free glutamate, not added MSG.
Traditional vs. Instant: Traditional miso paste is fermented slowly, while instant versions may contain added MSG to enhance flavor.
Glutamate is not MSG: Glutamate is a natural amino acid found in many foods, while MSG is a food additive derived from it.
Longer Fermentation, More Umami: The older and darker the miso (like red miso), the higher its natural glutamate content due to a longer aging process.
Check the Label: To avoid artificial MSG, always check the ingredients list for monosodium glutamate, especially with instant or pre-made products.
Health Benefits: Miso's natural fermentation provides probiotics and other nutrients, which are absent in pure MSG.

Understanding the Umami in Miso

Miso is a fundamental ingredient in Japanese cuisine, providing a savory umami flavor. The question of whether miso is high in MSG often stems from a misunderstanding of umami, the fifth basic taste. It's important to distinguish between glutamate, a naturally occurring amino acid, and monosodium glutamate (MSG), a manufactured food additive.

The Natural Fermentation Process

Traditional miso is made through the fermentation of soybeans, koji, salt, and sometimes grains. This process, which can take weeks to years, uses koji enzymes to break down proteins in soybeans into amino acids, including glutamic acid. The resulting free glutamate provides the umami taste.

Koji: A key element that breaks down proteins and starches.
Glutamate Release: Protein breakdown during fermentation releases natural glutamate.
Aging: Longer aging increases free glutamate, deepening umami flavor.

Glutamate vs. MSG: What's the Difference?

Glutamate is naturally present in foods like tomatoes and parmesan. The body processes it as a nutrient. MSG is a manufactured sodium salt of glutamic acid, used as a flavor enhancer. The body metabolizes both similarly. The distinction is whether glutamate is natural or added.

The Case of Instant Miso

Traditional miso is rich in natural glutamate, but instant miso products often contain added MSG. This is often due to quicker production methods that don't develop natural umami. To avoid added MSG, check ingredient lists for traditionally fermented miso.

Comparison: Miso vs. Added MSG


Feature	Traditional Miso Paste	Added MSG (flavor enhancer)
Source of Umami	Naturally occurring free glutamate from fermentation.	Manufactured monosodium glutamate, a crystalline extract.
Flavor Complexity	Rich, multi-dimensional flavor with salty, sweet, and tangy notes.	Pure, one-dimensional umami taste.
Production Method	Slow, traditional fermentation using soybeans, koji, and salt.	Commercial fermentation of starches or sugar cane to produce concentrated glutamate.
Ingredient List	Simple ingredients: soybeans, rice or barley, koji, salt.	Listed as 'monosodium glutamate' or 'MSG'.
Nutritional Profile	Contains probiotics and vitamins from fermentation.	No additional nutritional benefits; simply a flavor additive.

Different Types of Miso and their Umami Levels

Glutamate levels vary by miso type and fermentation time.

White Miso (Shiromiso): Milder, less intense umami.
Yellow Miso (Shinshu Miso): Deeper flavor, higher glutamate.
Red Miso (Akamiso): Longest fermentation, highest glutamate and potent umami.

Conclusion

Is miso high in MSG? No, traditional miso does not contain added MSG. Its umami comes from naturally occurring glutamate. High-quality miso achieves savory depth through natural fermentation. Added MSG is more likely in instant or pasteurized products. Choose authentically fermented miso by checking ingredient labels to enjoy its natural umami without added enhancers.

For more information on the chemistry of umami, you can consult resources like the Umami Information Center.

Frequently Asked Questions

No, the glutamate naturally found in miso is the same as the glutamate in many other protein-rich foods, and the human body processes it in the same way. It is a fundamental building block of proteins and is not harmful.

People who report sensitivity to added MSG may still be able to consume traditional miso without issue, as the glutamate is naturally occurring and part of a complex food matrix. However, individual sensitivities vary, and some may find any form of concentrated glutamate problematic.

No, traditional miso soup made with authentic miso paste and dashi does not contain added MSG. However, many instant, store-bought miso soup packets add MSG to boost flavor cheaply and quickly.

Always read the ingredient label. If 'monosodium glutamate,' 'MSG,' or other flavor enhancers are listed, it contains added MSG. High-quality miso paste will only list ingredients like soybeans, rice or barley, koji, and salt.

Red miso (akamiso) typically has the most natural glutamate. Its longer fermentation period allows for a greater breakdown of proteins, resulting in a more concentrated umami flavor compared to younger, lighter varieties like white miso.

Yes, the fermentation process is key. The koji mold added to the mixture breaks down the proteins in the soybeans, releasing glutamic acid. This free glutamic acid is what provides the potent, savory umami taste.

Yes, miso is an excellent natural flavor enhancer. It provides a more complex and nuanced umami flavor than pure MSG, along with other benefits like probiotics.