Does Miso Reduce Inflammation? What the Science Says

October 28, 2025 •

3 min read

Recent studies in both human and animal subjects have linked the consumption of fermented soy products, including miso, with a reduction in markers of chronic inflammation. This savory Japanese paste, made from fermented soybeans, contains a powerful combination of probiotics and antioxidants that work to combat inflammation in the gut and throughout the body.

Quick Summary

The anti-inflammatory effects of miso are linked to its rich content of probiotics and antioxidants, which support gut health and regulate immune responses. Fermentation increases the bioavailability of beneficial compounds, helping to reduce systemic inflammation.

Key Points

Miso's Probiotic Content: The fermentation process of miso produces beneficial probiotics, which are crucial for maintaining a healthy gut microbiome and regulating immune response.
Source of Antioxidants: Miso contains natural antioxidants, including soy isoflavones, that fight oxidative stress and help downregulate pro-inflammatory cytokines.
Promotes Short-Chain Fatty Acids: Miso consumption increases the production of beneficial short-chain fatty acids (SCFAs), such as butyrate, which support intestinal health.
Longer Fermentation for Potency: Darker, longer-fermented miso varieties generally offer a richer concentration of beneficial compounds and stronger anti-inflammatory potential.
Heat Sensitivity of Probiotics: To preserve the live probiotics, always add unpasteurized miso to foods after removing them from high heat.
Beneficial for Gut and Immune Health: By promoting a healthy gut, miso helps support a balanced immune system and can reduce systemic inflammation.

The Anti-Inflammatory Powerhouse: Probiotics and Beyond

Miso's potential to reduce inflammation is not based on a single component but a synergistic blend of compounds created during its fermentation process. The traditional method of making miso involves culturing soybeans with salt and a fungus called Aspergillus oryzae, also known as koji. This process unlocks numerous health benefits, with its anti-inflammatory effects being one of the most prominent.

The Critical Role of Probiotics

Fermentation makes miso a natural source of beneficial probiotics. These live microorganisms are key to a healthy gut microbiome, which, in turn, plays a major role in regulating the body's immune and inflammatory responses. A balanced and diverse gut flora helps prevent the overgrowth of harmful bacteria that can cause intestinal inflammation and other issues. Some of the benefits include:

Enhancing immune function: Probiotics can help balance the immune system, preventing overactive inflammatory responses.
Improving intestinal barrier integrity: The increase in beneficial gut bacteria helps fortify the gut lining, which can become permeable due to an unhealthy diet, leading to systemic inflammation.
Promoting nutrient absorption: A healthy gut is more efficient at absorbing nutrients, and fermentation reduces anti-nutrients in soybeans, further boosting absorption.

Antioxidants: Fighting Free Radical Damage

In addition to probiotics, miso contains potent antioxidants, such as soy isoflavones and phenolic acids, which help protect the body from oxidative stress.

Soy isoflavones: These compounds, particularly genistein, help regulate the body's inflammatory signaling pathways by downregulating pro-inflammatory cytokines.
Phenolic acids: Also derived from the fermentation of soybeans and grains, these compounds have free-radical-scavenging properties that combat the oxidative damage often associated with chronic inflammation.

Short-Chain Fatty Acids (SCFAs): The Gut's Fuel

The fermentation of fiber by gut microbes produces short-chain fatty acids (SCFAs), like butyrate, which have significant anti-inflammatory effects. Butyrate, in particular, serves as the primary energy source for the cells lining the colon, helping to maintain intestinal health and prevent inflammation. Research has shown that miso intake can increase SCFA production, further enhancing its anti-inflammatory properties.

Types of Miso and Anti-Inflammatory Potential

Not all miso is created equal. The type of miso, its ingredients, and fermentation time can all affect its nutrient profile and potential anti-inflammatory benefits. Lighter, younger miso tends to be milder, while darker, longer-fermented miso is richer in flavor and often has a more developed probiotic and antioxidant profile. For the most significant probiotic benefits, it is crucial to choose unpasteurized, 'live' miso.


Feature	Light Miso (Shiro)	Dark Miso (Aka)
Fermentation Time	Shorter (a few weeks to a few months)	Longer (up to several years)
Flavor Profile	Sweet, mild, less salty	Salty, rich, deep, umami
Probiotic Potential	Generally lower due to shorter fermentation	Potentially higher due to extended fermentation
Antioxidant Content	Contains antioxidants, but less concentrated	Higher concentration of isoflavones and other antioxidants
Best for...	Dressings, light sauces, soups finished off-heat	Robust soups, marinades, glazes

How to Maximize Miso's Benefits

To ensure you reap the most anti-inflammatory benefits from miso, follow these simple guidelines:

Use unpasteurized miso: Look for labels that specify 'unpasteurized' or 'live active cultures,' and find it in the refrigerated section of your grocery store.
Avoid high heat: Adding miso to boiling water will kill the live probiotics. Instead, remove soup from heat and let it cool slightly before stirring in the miso paste.
Incorporate it into cold dishes: Miso works wonderfully in salad dressings, marinades, and sauces that are not cooked, which preserves the probiotic content.
Balance with low-sodium ingredients: Be mindful of miso's high sodium content and pair it with fresh vegetables and other low-sodium foods to maintain a healthy balance.

Conclusion: A Beneficial Addition for Fighting Inflammation

While more human studies are needed to fully understand all of miso's anti-inflammatory mechanisms, the existing evidence is compelling. The combination of gut-supporting probiotics, powerful antioxidants, and SCFA production makes miso a valuable addition to an anti-inflammatory diet. Its benefits for gut health and immune regulation are well-documented, suggesting a promising role in combating chronic inflammation. By choosing unpasteurized varieties and using them correctly in your cooking, you can easily incorporate this flavorful and healthful fermented food into your lifestyle. For more information on fermented foods and health, the National Institutes of Health provides extensive research and studies.

Frequently Asked Questions

Not all miso is created equal. For maximum anti-inflammatory benefits from probiotics, choose unpasteurized miso with live cultures. Pasteurized varieties are still nutritious but lack the live bacteria.

To preserve live probiotics, add unpasteurized miso at the end of cooking, after the heat has been turned off and the food has cooled slightly. It's also excellent in cold preparations like dressings and dips.

While miso is high in sodium, studies suggest that its fermented compounds may counteract the effect of salt on blood pressure in many people. It's still wise to consume it in moderation as part of a balanced diet and to choose lower-sodium versions if needed.

Research suggests that miso's probiotics and anti-inflammatory properties may help manage conditions like inflammatory bowel disease (IBD) by improving the gut microbiome. However, it is not a cure and should be discussed with a healthcare provider.

Cooking miso at high temperatures can kill the live probiotics, but the paste still contains valuable enzymes, peptides, and antioxidants that aid digestion and have anti-inflammatory effects. The fermentation process creates numerous beneficial compounds that persist even after heating.

Those with a soy allergy should avoid miso as it is made from soybeans. However, some with a mild intolerance find that the fermentation process makes miso easier to digest, as it breaks down many of the soy compounds.

Like other fermented foods, miso introduces beneficial bacteria to the gut, but its unique composition of soy isoflavones and other fermentation byproducts provides specific antioxidant and anti-inflammatory properties. Its effectiveness depends on individual gut flora and other dietary factors.