Does Miso Paste Affect Blood Pressure? Separating Fact from Sodium Concern

November 15, 2025 •

3 min read

Despite its significant sodium content, recent research suggests that miso paste does not negatively affect blood pressure in the same way as regular table salt. This surprising finding often leads to the important question: Does miso paste affect blood pressure, and how do its unique fermented properties manage to counteract the salt?

Quick Summary

Studies show that bioactive peptides from fermented miso can mitigate the blood pressure-raising effects of its sodium. Observational evidence suggests habitual miso soup consumption is not linked to hypertension incidence, and may even help lower heart rate.

Key Points

Counterintuitive Effects: Despite its high salt content, miso paste has not been found to raise blood pressure in the same way as regular table salt.
Bioactive Peptides: The fermentation process in miso produces unique peptides with ACE-inhibitory properties, which can help lower blood pressure by relaxing blood vessels.
Observational Studies: Frequent consumption of miso soup is not associated with an increased incidence of hypertension in studies of Japanese adults.
Decreased Nighttime Pressure: Some research shows that long-term intake of miso may significantly decrease nighttime blood pressure in those with high-normal or stage I hypertension.
Sympathetic Nervous System: Miso's ingredients are thought to calm the sympathetic nervous system, which helps regulate heart rate and blood pressure.
Balanced Approach: The health benefits of miso are part of a broader dietary context, and it is best consumed in moderation alongside other healthy, low-sodium foods.
Heart-Healthy Minerals: Adding potassium-rich vegetables to miso soup can help further offset sodium by increasing its excretion from the body.

Miso's High Sodium vs. Its Health-Protecting Compounds

Miso, a staple of Japanese cuisine, is a fermented paste made from soybeans, salt, and koji. While its high sodium content is a concern for individuals monitoring salt intake, particularly those with hypertension, research indicates that miso's impact on blood pressure is different from an equivalent amount of table salt. The fermentation process introduces unique compounds that appear to mitigate salt-induced blood pressure elevation.

The Role of Fermentation in Mitigating Salt Effects

The fermentation of soybeans breaks down proteins into bioactive peptides, some of which exhibit angiotensin-converting enzyme (ACE)-inhibitory properties. By inhibiting ACE, these peptides can help relax blood vessels and potentially lower blood pressure. Studies also suggest that compounds in miso may calm the sympathetic nervous system, contributing to a lower heart rate and more stable blood pressure, an effect observed in animal studies that wasn't seen with equivalent table salt intake.

Observational vs. Interventional Findings

Observational studies in Japan have generally found no positive correlation between frequent miso soup consumption and high blood pressure. Some interventional studies have even shown potential benefits, such as a 2019 study where long-term miso intake was associated with significantly decreased nighttime blood pressure in individuals with high-normal or stage I hypertension. However, the broader dietary context, which often includes other healthy foods in a traditional Japanese diet, is also acknowledged as a factor.

Comparison: Miso Sodium vs. Table Salt Sodium


Feature	Miso Sodium	Table Salt Sodium
Source	Naturally occurring, fermented soybeans and grains.	Refined sodium chloride (NaCl).
Associated Compounds	Bioactive peptides (e.g., ACE-inhibitors), probiotics, and antioxidants.	Lacks mitigating bioactive compounds.
Impact on Blood Pressure	Mitigated or neutral effect due to protective compounds. May lower nighttime blood pressure.	Increases blood pressure, especially in salt-sensitive individuals.
Role in Diet	Adds umami flavor, probiotics, and nutrients.	Primarily adds saltiness, no probiotic benefits.
Dietary Context	Often consumed as part of a balanced diet with vegetables and other whole foods.	Can be added to processed foods and cooking, often excessively.

How to Consume Miso Healthily

For those managing blood pressure, incorporating miso into a balanced, heart-healthy diet is recommended. Key tips include:

Choose Low-Sodium Miso: Reduced-sodium options are available and are a good choice.
Moderation is Key: While less impactful than table salt, excessive intake of miso should still be avoided.
Pair with Potassium-Rich Foods: Potassium helps balance sodium levels. Add vegetables like spinach, mushrooms, and zucchini to miso soup.
Focus on Unpasteurized Miso: Unpasteurized miso contains live probiotics; add it to dishes after high heat to preserve them.
Eat with Complementary Foods: Enjoy miso as part of a meal including ingredients like tofu, wakame seaweed, and mushrooms for added nutrients.

Conclusion

Moderate consumption of miso paste as part of a balanced diet appears unlikely to negatively affect blood pressure for most individuals, including those with mild hypertension, unlike regular table salt. The bioactive peptides produced during fermentation may counteract sodium's effects, with some studies indicating a potential mild blood pressure-lowering benefit. Opting for low-sodium varieties and pairing miso with potassium-rich foods can further enhance its health benefits. Individuals with medical concerns should consult a healthcare professional. For more detailed information on research regarding miso's health effects, refer to studies like the {Link: biomedcentral.com https://environhealthprevmed.biomedcentral.com/articles/10.1186/s12199-020-00883-4}.

Frequently Asked Questions

Yes, in moderation, and preferably a low-sodium variety. Evidence suggests that the bioactive compounds created during fermentation can help counteract the blood pressure-raising effects of its sodium content, unlike regular salt.

Yes. While chemically both are sodium, the sodium in fermented miso is paired with bioactive peptides and other compounds that mitigate its hypertensive effects. In contrast, regular table salt lacks these protective elements and is more likely to increase blood pressure.

If you are concerned about your salt intake or have hypertension, choosing a low-sodium miso paste is a smart choice. These versions offer a similar flavor profile and fermentation benefits with a reduced sodium load.

Yes. Beyond its unique effect on blood pressure, miso is rich in probiotics that support gut health, which is linked to cardiovascular health. It also contains plant compounds that may help lower cholesterol levels.

You can help reduce the overall impact by adding potassium-rich vegetables like wakame seaweed, mushrooms, or spinach to your soup. Potassium helps your body excretes excess sodium.

Not directly, but color can be a general indicator of saltiness. Darker misos are typically saltier and have been fermented longer. A balanced, moderate approach is important regardless of the type.

To preserve the live probiotics, it is best to add miso paste to your soup or dish after removing it from high heat. This ensures you receive the full spectrum of its probiotic benefits.