Functional Foods · Fermented food
Miso
Fermented soybean paste (Glycine max) · also called Japanese soybean paste, miso paste
Miso is a salty paste made by fermenting soybeans with salt and koji mould. It is used in small amounts, most often in miso soup. No trial of miso itself for a health outcome was found, and the studies of people who eat it are observational. The main cautions are its salt, about 634 mg of sodium in a tablespoon, and soy allergy.
General information, not medical advice. Last substantive update · Not medically reviewed. A named clinician has not signed off on this page. How this page is made
About Miso
Miso is a salty paste made from fermented soybeans. It is a seasoning, used in small amounts. It is a food, not a proven remedy: no trial of miso for a health outcome was found, and the cancer and liver findings are observational and mix miso soup with the rest of a diet.
What it is
Miso is a traditional Japanese fermented food, known mainly as the seasoning in miso soup. A 2021 review describes how it is made in two stages. A mould such as Aspergillus oryzae is grown on a base to make koji. The koji is then added to a salt and soybean mash, which is left to ferment for up to 2 years. The review says very little research has described the microbes involved.
Because the main ingredient is soybean, miso is a soy food. It is also a different food from tofu, natto or tempeh, which have their own pages.
Nutrition and salt
USDA data for miso, per 100 g: 198 kcal, 12.79 g protein, 6.01 g fat, 25.37 g carbohydrate, 5.4 g fibre, 2.56 mg zinc, 0.859 mg manganese, 0.42 mg copper and 29.3 micrograms vitamin K. A tablespoon (17 g) has about 34 kcal, 2.2 g protein and 0.9 g fibre.
The salt stands out: 3,728 mg of sodium per 100 g, about 634 mg in a tablespoon. For comparison, the FDA gives a Daily Value of less than 2,300 mg of sodium a day, and WHO recommends less than 2,000 mg. USDA lists one sample, and brands, colours and low-salt types differ, so check the label.
What the research shows
No trial of miso on its own for a health outcome was found. What exists is mainly observational. In 3,501 Japanese adults, a way of eating rich in soybean products, vegetables, fish, fruit and miso soup went with a lower fatty liver index. Miso soup cannot be separated from the rest of that pattern.
Pooled trials of fermented soy products found small drops in fasting glucose and total cholesterol compared with controls. The abstract does not name the products, so it is not shown for miso, and an umbrella review calls the benefit of fermented soy inconclusive, with some studies indicating possible harm.
For cancer, two pooled analyses of observational studies found no link between miso soup and total cancer (RR 0.99) or gastric cancer. A Japanese cohort of 42,535 adults found high salt intake went with more mouth, throat and oesophagus cancers, and miso soup was positively linked with that group while other salty foods were not. These are links in food questionnaires, not proof of cause.
Fermented is not the same as probiotic
An expert panel defines fermented foods as foods made through desired microbial growth and enzymatic conversions of food components, and separates them from probiotics. Whether a given miso has live microbes, whether they survive heating in soup, and whether they help health were not shown in the sources read. Probiotic supplements are a different question.
At a glance
Traditional uses history, not proof
- Eaten as a seasoning, most often in miso soup, in Japanese cooking
- Long use as food is not proof that it treats any condition
Studied for research
- Protein, fibre and minerals, high certainty for the nutrient content, with a lot of sodium
- Liver fat score, very-low certainty (one food-pattern cohort)
- Blood sugar and cholesterol, low certainty (fermented soy trials, not miso)
- Cancer risk, low and mixed (observational)
- Blood pressure, insufficient evidence
- Gut health and 'probiotic' claims, insufficient evidence
Main compounds
- Sodium (from the salt in the mash)
- Soy protein
- Dietary fibre
- Zinc, manganese and copper
- Vitamin K
- Biogenic amines (tyramine, histamine), formed in fermentation
Common forms
- Miso paste (USDA item 172442, values read)
- Miso soup (miso in broth; studied in Japanese cohorts, values not read)
- White, yellow, red and low-salt types (not read)
- Probiotic or soy isoflavone supplements are different products and are not covered
Research links: 2025 cohort: food pattern with miso soup and fatty liver index · 2024 review: soy products and cancer risk, including miso soup · 2026 cohort: salt, miso soup and mouth, throat and oesophagus cancers · Research Library · Genes & Biomarkers Library
What it is and its history
- Accepted scientific name
- Miso (Japanese fermented soybean paste)
- Naming authority
- A processed food, not a plant. The main ingredient, soybean, is Glycine max (L.) Merr. (GBIF accepted name).
- Common names
- Miso (English); Japanese soybean paste (English); Miso (Spanish)
- Family or group
- Fabaceae (the legume or pea family) for the soybean, as given by GBIF. Miso itself is a fermented food, not a plant.
- Classification
- Plantae > Tracheophyta > Magnoliopsida > Fabales > Fabaceae > Glycine > Glycine max
- Native range
- Not verified from a source read.
- What it looks like
- Fruit: Miso is a paste. USDA gives household portions of 1 tablespoon (17 g) and 1 cup (275 g).
- Harvest and processing
- A 2021 review describes a two-stage fermentation. First a mould such as Aspergillus oryzae is grown on a substrate to make koji. The koji is then added to a salt and soybean mash, which ferments with bacteria and yeast for up to 2 years. The review says very little research has characterised the microbial process. Types (white, yellow, red), grains other than soybean and low-salt versions were not read from a source.
- Look-alikes and adulterants
- Name: Natto, tempeh, soy sauce and gochujang or doenjang; Note: Other fermented soy foods with their own pages; they differ in nutrients, salt, microbes and amines.; Name: Koji and amazake; Note: Koji is the mould-grown starter used to make miso; it is not the same as miso.; Name: Probiotic supplements; Note: Probiotics are a different kind of product from a fermented food.
- Sustainability and conservation
- Not assessed.
Photographs
Traditional use and history history, not clinical proof
| Tradition or era | Documented use | Source |
|---|---|---|
| Traditional Japan | A 2021 review calls miso a traditional Japanese fermented food, known mainly as the seasoning in miso soup. No source read gives its origin date or place. | Allwood JG et al. J Food Sci 2021 (PMID 34056716), abstract read |
Traditional use shows how it was used. It does not show that it works or is safe today.
What is inside, and how it may work
What it contains and how those compounds act in cells and animals. Laboratory and animal mechanisms are not proven effects in people.
Main compounds
| Compound | Family | Where it is concentrated | Activity studied | Level of evidence |
|---|---|---|---|---|
| Sodium | mineral | Added as salt in the mash USDA per 100 g: 3,728 mg; about 634 mg per tablespoon (17 g) | High sodium intake is linked with raised blood pressure (FDA, WHO). 16 14 17 | Authoritative guidance |
| Protein | protein | Soybean USDA per 100 g: 12.79 g; about 2.2 g per tablespoon | Soy protein is the source of the soy allergen. 16 13 | Human data |
| Dietary fibre | fibre | Soybean USDA per 100 g: 5.4 g; about 0.9 g per tablespoon | A nutrient amount only. 16 | Human data |
| Zinc, manganese and copper | mineral | Whole paste USDA per 100 g: zinc 2.56 mg, manganese 0.859 mg, copper 0.42 mg | Nutrient amounts only. Zinc from a zinc tablet was less absorbed when taken with miso soup in a small study. 16 9 | Human data |
| Vitamin K (phylloquinone) | vitamin | Whole paste USDA per 100 g: 29.3 micrograms; about 5 micrograms per tablespoon | A nutrient amount only; relevant to warfarin in principle. 16 | Human data |
| Biogenic amines (tyramine, histamine) | amine | Formed in fermentation No miso value read | Some fermented foods contain them above documented toxic doses; effects include migraines, raised blood pressure and fast heartbeat. 8 3 | Review |
Mechanisms, receptors and pathways
| Target or pathway | Gene or receptor | What was found | Level |
|---|---|---|---|
| Two-stage fermentation (koji, then salt and soybean mash) | Not applicable | A mould such as Aspergillus oryzae is grown to make koji, then bacteria and yeast ferment the koji, salt and soybean mash for up to 2 years. The authors say the microbial process is little studied. 1 | Review |
| Biogenic amine formation | Not applicable | Biogenic amines are products of amino acids broken down by microbes during fermentation. Starter cultures that do not make them have been proposed to lower them in fermented soybean foods. 8 3 | Review |
| Sodium and blood pressure | Not specified in the sources read | The FDA and WHO state that diets higher in sodium are linked with higher blood pressure. This is general guidance, not a test with miso. 14 17 | Authoritative guidance |
Absorption, metabolism and elimination
- Absorption
- Not found for miso nutrients. A small study found that miso soup, among other foods, reduced absorption of a zinc acetate supplement.
- Distribution
- Not found.
- Metabolism
- Not found.
- Elimination
- Not found.
- Bioavailability
- Not established for miso nutrients in people.
Isolated compounds versus whole extracts
The cohort results are for miso soup or for food patterns that include it. The trial results are for fermented soy products in general. Probiotic supplements, soy isoflavone supplements and zinc tablets are different products and are not covered by these food results.
Nutritional composition
Nutrition from USDA FoodData Central (SR Legacy, April 2018 release; item 172442 'Miso'; values read 2026-10-26 from a saved copy of the data feed in the repo). Per 100 g: 198 kcal, 12.79 g protein, 6.01 g fat (1.025 g saturated), 25.37 g carbohydrate (6.2 g sugars), 5.4 g fibre, 3,728 mg sodium, 210 mg potassium, 57 mg calcium, 2.49 mg iron, 48 mg magnesium, 159 mg phosphorus, 2.56 mg zinc, 0.859 mg manganese, 0.42 mg copper, 7 micrograms selenium, 29.3 micrograms vitamin K and 0.08 micrograms vitamin B12. One tablespoon (17 g, the 100 g values multiplied by 0.17): about 34 kcal, 2.2 g protein, 1.0 g fat, 4.3 g carbohydrate, 0.9 g fibre, 634 mg sodium, 36 mg potassium, 10 mg calcium, 0.4 mg iron, 0.4 mg zinc and 5 micrograms vitamin K. USDA lists one sample; brands, colours (white, yellow, red) and low-salt versions differ, so check the label. Miso soup (miso diluted in broth) was not read.
1 high certainty2 low certainty1 very low certainty2 not enough evidence
What was looked at
The 6 benefits and uses checked for Miso, each with how strong the evidence is. Tap one to open it.
- Nutrient content (and salt)High certainty
- Liver fat (fatty liver index) in a Japanese food patternVery low certainty
- Blood sugar, cholesterol and waist size (fermented soy trials)Low certainty
- Cancer risk (miso soup, soy paste and salt)Low certainty
- Blood pressure (Japanese diet score)Not enough evidence
- Gut health and the 'probiotic' questionNot enough evidence
Lab markers tracked in the studies
Fatty liver index (FLI)Fasting blood glucoseTotal cholesterolHigh blood pressure (prevalence)Total cancer risk (pooled relative risk)
What is Miso good for?
The main studied uses and how strong the human evidence is for each. No study tested miso on its own for a health outcome; most results are for food patterns that include miso soup or for fermented soy in general.
Benefits, one by one
Each card is a research question, not a promise. Tap a goal to filter. Open a card to see the studies, doses and limits.
Nutrient content (and salt)
High certaintyMiso paste gives protein, fibre, manganese, copper and zinc, but it is also very salty. Per 100 g, USDA lists 12.79 g protein, 5.4 g fibre and 3,728 mg sodium. A tablespoon (17 g) has about 34 kcal, 2.2 g protein and 634 mg sodium.
2 studiesUSDA item 172442 (miso paste). Miso soup, different colours and types…
Studies, doses and limits
What the trials found
No trial was read showing that eating miso corrects any nutrient shortfall. A tablespoon is a small amount of food, so the nutrients it adds are small, while its sodium is large.
Results
On paper, miso is a modest source of protein, fibre and some minerals, and a high-sodium food. Brands and types differ, so the label shows the true amount.
Effect sizes as reported
USDA per 100 g: 198 kcal, 12.79 g protein, 5.4 g fibre, 2.56 mg zinc, 0.859 mg manganese, 0.42 mg copper, 2.49 mg iron, 57 mg calcium, 3,728 mg sodium. Per tablespoon (17 g): about 34 kcal, 2.2 g protein, 0.9 g fibre, 634 mg sodium.
Why this rating
High that the USDA item contains these amounts (reference data for one USDA sample). Not tested as a way to fix any shortfall. Real products vary.
Form and dose studied
USDA item 172442 (miso paste). Miso soup, different colours and types, and low-salt miso were not read.
Who was studied
General diet.
Limits
Nutrient facts, not trials. One USDA sample from SR Legacy (2018). White, yellow and red types are sold; no source read says how they differ.
Why researchers looked
Miso is a soy food used as a seasoning, so its nutrients and its salt are the first things people ask about.
Traditional use
Miso is a traditional Japanese fermented food, known mainly as the seasoning in miso soup. Long use as food is not proof that it treats any condition.
Proposed mechanism Nutrient database
These are nutrient amounts in the paste, taken from USDA tables. The salt comes from the salt and soybean mash it is fermented in.
A proposed mechanism does not show that the effect happens in people.
Salt is the main caution; see the Safety tab.
Liver fat (fatty liver index) in a Japanese food pattern
Very low certaintyIn 3,501 Japanese adults, a way of eating rich in soybean products, vegetables, fish, fruit and miso soup went with a lower fatty liver index. Miso soup was one part of that pattern, so the result is not about miso on its own.
1 studiesMiso soup as one part of a food pattern. Not miso alone.
Studies, doses and limits
What the trials found
Observational cohort (Nagahama Study). Food habits came from a 15-item questionnaire. The pattern with miso soup was linked with a lower fatty liver index at the start and 5 years later (coefficients -3.01 and -1.03).
Results
A small link with a liver-fat score, for a whole pattern. Not shown for miso itself.
Effect sizes as reported
Partial regression coefficients -3.01 (baseline) and -1.03 (5 years), p<0.01 for both. Strongest in people with BMI under 23.
Why this rating
One observational cohort, a pattern of many foods, a questionnaire of 15 items and an index that is a formula rather than a scan. It cannot separate miso from the other foods.
Form and dose studied
Miso soup as one part of a food pattern. Not miso alone.
Who was studied
3,501 adults in a Japanese community cohort.
Limits
Pattern-level. Cannot show cause. People eating this pattern may differ in many other ways.
Why researchers looked
Researchers look for eating patterns linked with fatty liver disease.
Traditional use
Miso soup is part of the traditional Japanese diet.
Proposed mechanism Observational
Not shown. The study found a link between a food pattern and a score; it did not test a mechanism.
A proposed mechanism does not show that the effect happens in people.
Miso soup is salty; see the Safety tab.
Blood sugar, cholesterol and waist size (fermented soy trials)
Low certaintyPooled trials of fermented soy products found small drops in fasting blood sugar, total cholesterol and waist size compared with controls. The abstract does not say which products were tested, so this is not shown for miso.
2 studiesFermented soy products of unnamed types. Not miso alone.
Studies, doses and limits
What the trials found
A pooled analysis of 15 randomised trials found, versus controls, lower fasting glucose (-6.39 mg/dL), total cholesterol (-5.0 mg/dL), BMI (-0.14 kg/m2), waist (-1.50 cm) and visceral fat. Other measures did not change significantly. An umbrella review of soy foods called the benefit of fermented soy products inconclusive and said some studies indicated possible adverse effects.
Results
Small changes in a few measures, mixed with no change in others. Not specific to miso.
Effect sizes as reported
Fasting glucose -6.39 mg/dL (95% CI -10.38 to -2.40); total cholesterol -5.0 mg/dL (-6.60 to -3.39); waist -1.50 cm (-2.94 to -0.07); BMI -0.14 kg/m2 (-0.28 to -0.01); visceral fat -692.17 mm2.
Why this rating
Low for miso: the pooled trials used fermented soy products that the abstract does not name, the BMI and waist changes are tiny, and the wider umbrella review calls the evidence for fermented soy inconclusive. No miso-specific trial was found.
Form and dose studied
Fermented soy products of unnamed types. Not miso alone.
Who was studied
Adults in 15 randomised trials (details not in the abstract).
Limits
Not specific to miso. Only abstracts were read, so trial quality and differences between trials are not known.
Why researchers looked
Fermented soy foods such as miso, natto and tempeh are studied together for metabolic health.
Traditional use
Fermented soy foods are eaten in several Asian cuisines. Long use as food is not proof that they treat any condition.
Proposed mechanism Not established
Not shown for miso. No mechanism was tested in the analysis.
A proposed mechanism does not show that the effect happens in people.
See the Safety tab for salt and soy allergy.
Cancer risk (miso soup, soy paste and salt)
Low certaintyPooled observational studies found no link between miso soup and total cancer risk (RR 0.99) or gastric cancer risk. One Japanese cohort found miso soup, as a source of salt, went with a higher risk of oral, throat and oesophageal cancers combined. High salt intake itself is the main concern in these studies.
3 studiesMiso soup as eaten in Japan. Not miso paste in other dishes.
Studies, doses and limits
What the trials found
A pooled analysis of 52 studies found no association between miso soup (RR 0.99, 95% CI 0.87 to 1.12) or soy paste (RR 1.00) and total cancer risk. Another pooled analysis of 26 cohorts found no effect of high or moderate miso soup intake on gastric cancer (RR 1.04 and 1.02), while high salt intake went with higher risk (RR 1.25). In 42,535 Japanese adults, high salt intake went with higher risk of oral, pharyngeal and oesophageal cancers combined (HR 1.67); miso soup was positively associated with that risk and other high-salt foods were not (no number in the abstract).
Results
Mixed. The two pooled analyses found no link for miso soup; one large cohort found a link for the combined mouth, throat and oesophagus cancers, tied to salt.
Effect sizes as reported
Total cancer: miso soup RR 0.99 (0.87 to 1.12). Gastric cancer: miso soup high RR 1.04 (0.90 to 1.19), moderate 1.02 (0.94 to 1.11); high salt RR 1.25 (1.10 to 1.41). Mouth, throat and oesophagus: highest vs lowest third of salt HR 1.67 (1.08 to 2.61).
Why this rating
All observational and based on food questionnaires, with only 145 cancers in the cohort. The results point different ways for different cancers. They show links, not cause.
Form and dose studied
Miso soup as eaten in Japan. Not miso paste in other dishes.
Who was studied
Mostly Japanese adults.
Limits
Observational. Food questionnaires can be wrong and people who eat more miso soup differ in other ways. Total cancer is a very broad outcome.
Why researchers looked
Miso is a salty food and Japanese diets are high in salt, which has been linked with some stomach and throat cancers.
Traditional use
Miso soup is a common part of the Japanese diet.
Proposed mechanism Observational
Not shown. The cohorts found links with salt intake; they did not test how salt or miso could act.
A proposed mechanism does not show that the effect happens in people.
High overall salt intake is the common thread. See the Safety tab.
Blood pressure (Japanese diet score)
Not enough evidenceIn 12,213 Japanese workers, a score for the traditional Japanese diet, which includes miso soup, was not linked with having high blood pressure. Miso soup was only one of nine items in the score.
3 studiesMiso soup as one item in a diet score.
Studies, doses and limits
What the trials found
In a cross-sectional study, the adjusted prevalence ratios of hypertension from the lowest to the highest quarter of the traditional diet score were 1.00, 0.94, 0.98 and 0.96 (P for trend 0.29). No miso-only blood pressure study was found.
Results
No clear link for a score of nine foods; nothing specific to miso.
Effect sizes as reported
Highest vs lowest quarter: prevalence ratio 0.96 (95% CI 0.90 to 1.02).
Why this rating
One cross-sectional study of a diet score. It cannot separate miso soup and it cannot show what came first. No trial of miso and blood pressure was found.
Form and dose studied
Miso soup as one item in a diet score.
Who was studied
12,213 employees of Japanese companies.
Limits
Cross-sectional. Many foods in one score. The sodium in miso is a caution for blood pressure; this study does not cancel it.
Why researchers looked
The traditional Japanese diet has been thought to raise blood pressure because it is high in sodium.
Traditional use
Miso soup is a common part of the traditional Japanese diet.
Proposed mechanism Authoritative guidance
Not tested. Guidance bodies say diets high in sodium are linked with raised blood pressure.
A proposed mechanism does not show that the effect happens in people.
Miso is high in sodium by USDA data; see the Safety tab.
Gut health and the 'probiotic' question
Not enough evidenceMiso is a fermented food, but fermented does not mean probiotic. No study read showed that live microbes in miso reach the gut or help health.
2 studiesMiso paste and miso soup. Heating in soup and the effect on microbes …
Studies, doses and limits
What the trials found
No trial of miso and gut symptoms or the gut microbiome was found. A review of koji and miso says very little research has characterised the microbes involved in making miso.
Results
Not shown. Whether a given miso still has live microbes, and whether that matters for health, was not established in the sources read.
Why this rating
No human study of miso and gut health was found; only a definition and a review of how miso is made.
Form and dose studied
Miso paste and miso soup. Heating in soup and the effect on microbes was not read.
Limits
Expert statement and review only; no outcome data for miso.
Why researchers looked
Fermented foods are often described as good for the gut.
Traditional use
Miso is a traditional fermented food.
Proposed mechanism Authoritative guidance
The ISAPP expert panel defines fermented foods as foods made through desired microbial growth and enzymatic conversions of food components, and separates them from probiotics. It gives a mechanistic rationale for how fermented foods could help gut and general health; this is a rationale, not a finding for miso.
A proposed mechanism does not show that the effect happens in people.
Some fermented foods contain biogenic amines; see the Safety tab.
Connections to the rest of health
How Miso connects to the rest of our health knowledge graph. Every link says what kind of connection it is. A safety link (for example to the liver) is a warning, not a benefit. A study that merely mentions a topic never creates a benefit link.
Explore every connection: goals, body systems, organs, symptoms, genes
A. Wellness goals
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Preventive Wellness | High certainty | Nutrient content (and salt): Miso paste gives protein, fibre, manganese, copper and zinc, but it is also very salty. Per 100 g, USDA lists 12.79 g protein, 5.4 g fibre and 3,728 mg sodium. A tablespoon (17 g) has about 34 kcal, 2.2 g protein and 634 mg sodium. | 16 14 | |
| Liver Health | Very low certainty | Liver fat (fatty liver index) in a Japanese food pattern: In 3,501 Japanese adults, a way of eating rich in soybean products, vegetables, fish, fruit and miso soup went with a lower fatty liver index. Miso soup was one part of that pattern, so the result is not about miso on its own. | 10 | |
| Blood Sugar Balance | Low certainty | Blood sugar, cholesterol and waist size (fermented soy trials): Pooled trials of fermented soy products found small drops in fasting blood sugar, total cholesterol and waist size compared with controls. The abstract does not say which products were tested, so this is not shown for miso. | 4 2 | |
| Cholesterol Balance | Low certainty | Blood sugar, cholesterol and waist size (fermented soy trials): Pooled trials of fermented soy products found small drops in fasting blood sugar, total cholesterol and waist size compared with controls. The abstract does not say which products were tested, so this is not shown for miso. | 4 2 | |
| Healthy Weight | Low certainty | Blood sugar, cholesterol and waist size (fermented soy trials): Pooled trials of fermented soy products found small drops in fasting blood sugar, total cholesterol and waist size compared with controls. The abstract does not say which products were tested, so this is not shown for miso. | 4 2 | |
| Preventive Wellness | Low certainty | Cancer risk (miso soup, soy paste and salt): Pooled observational studies found no link between miso soup and total cancer risk (RR 0.99) or gastric cancer risk. One Japanese cohort found miso soup, as a source of salt, went with a higher risk of oral, throat and oesophageal cancers combined. High salt intake itself is the main concern in these studies. | 11 12 7 | |
| Blood Pressure Support | Not enough evidence | Blood pressure (Japanese diet score): In 12,213 Japanese workers, a score for the traditional Japanese diet, which includes miso soup, was not linked with having high blood pressure. Miso soup was only one of nine items in the score. | 6 14 17 | |
| Gut Digestive Health | Not enough evidence | Gut health and the 'probiotic' question: Miso is a fermented food, but fermented does not mean probiotic. No study read showed that live microbes in miso reach the gut or help health. | 5 1 |
B. Body systems
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Digestive System | Biological association | High certainty | Studied for: Nutrient content (and salt) Studied for: Liver fat (fatty liver index) in a Japanese food pattern | 16 14 10 11 12 7 5 1 |
| Endocrine System | Biological association | Low certainty | Studied for: Blood sugar, cholesterol and waist size (fermented soy trials) | 4 2 |
| Cardiovascular System | Biological association | Low certainty | Studied for: Blood sugar, cholesterol and waist size (fermented soy trials) Studied for: Blood pressure (Japanese diet score) | 4 2 6 14 17 |
E. Health conditions
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Food allergy | Adverse effect or risk | Documented risk | Soybeans are a major US food allergen; reactions can be severe. Soybeans are a major food allergen. Preparation or compound: Soy protein in miso |
13 |
| Essential hypertension | Adverse effect or risk | Documented risk | Miso has about 634 mg of sodium per tablespoon (USDA); high sodium intake is linked with raised blood pressure (FDA, WHO). A caution, not a benefit. Miso has about 634 mg of sodium per tablespoon; high sodium intake is linked with raised blood pressure. A caution, not a benefit. Preparation or compound: Sodium in miso |
16 14 17 |
I. Biomarkers
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Fatty liver index (FLI) | Biological association | Very low certainty | Measured in trials: lowered (link). A lab change is not the same as a health benefit. | 10 |
| Fasting blood glucose | Biological association | Low certainty | Measured in trials: lowered. A lab change is not the same as a health benefit. | 4 |
| Total cholesterol | Biological association | Low certainty | Measured in trials: lowered. A lab change is not the same as a health benefit. | 4 |
| High blood pressure (prevalence) | Biological association | Not enough evidence | Measured in trials: no significant change. A lab change is not the same as a health benefit. | 6 14 |
| Total cancer risk (pooled relative risk) | Biological association | Low certainty | Measured in trials: no significant change. A lab change is not the same as a health benefit. | 11 |
K. Biological pathways
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Sodium | Preliminary mechanism | Authoritative guidance | Miso is a high-sodium food; sodium is linked with raised blood pressure. | 16 14 17 |
| Fatty liver index | Preliminary mechanism | Human | A food pattern including miso soup went with a lower index in one cohort. | 10 |
| Fasting glucose and total cholesterol | Preliminary mechanism | Human | Fermented soy products in general lowered both a little in pooled trials; not shown for miso. | 4 |
L. Active compounds
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Sodium | Biological association | Authoritative guidance | High sodium intake is linked with raised blood pressure (FDA, WHO). Preparation or compound: Added as salt in the mash |
16 14 17 |
| Protein | Biological association | Human | Soy protein is the source of the soy allergen. Preparation or compound: Soybean |
16 13 |
| Dietary fibre | Biological association | Human | A nutrient amount only. Preparation or compound: Soybean |
16 |
| Zinc, manganese and copper | Biological association | Human | Nutrient amounts only. Zinc from a zinc tablet was less absorbed when taken with miso soup in a small study. Preparation or compound: Whole paste |
16 9 |
| Vitamin K (phylloquinone) | Biological association | Human | A nutrient amount only; relevant to warfarin in principle. Preparation or compound: Whole paste |
16 |
| Biogenic amines (tyramine, histamine) | Biological association | Review | Some fermented foods contain them above documented toxic doses; effects include migraines, raised blood pressure and fast heartbeat. Preparation or compound: Formed in fermentation |
8 3 |
Each connection is stored with the ingredient, the connected record, the kind of connection, the evidence status, the supporting studies, the preparation or compound involved, and a review date (last reviewed October 26, 2026).
Evidence at a glance: what changed in 2 lab markers
Tap a number to show only those markers. Counts are markers, not people.
The evidence
The research centre for Miso. Every record here was checked against PubMed or the publisher's page; we never list a study we have not verified.
Evidence by outcome
Bars show how many studies we found for each outcome, not how well it works. People are added up across trials only (reviews are not added, to avoid double counting).
How we rate evidence
High certainty
Several well-run trials or reviews agree; further research is unlikely to change the picture much.
Moderate certainty
Good trials point the same way, but some doubt remains.
Low certainty
Small, short or inconsistent trials. The finding could change with better research.
Very low certainty
Very little or very weak human data. Treat as a possibility only.
Mixed findings
Trials or reviews disagree with each other.
Not enough evidence
Not enough human research to say either way.
Evidence against
Good research found no benefit, or found harm.
We take the reviewers' own risk-of-bias and GRADE statements where they exist, and otherwise judge from study size, design, consistency, directness and whether a product matches what is sold. Many publications do not make evidence high. Method note: We started from our existing miso summary and its reference list, re-checked nutrition against saved USDA FoodData Central data, re-read the FDA and WHO sodium pages and the FDA allergy page, and re-read PubMed abstracts for each study. Two pooled analyses reporting miso soup were added from a new search. Only abstracts were read for studies. Items we could not verify are flagged in the research gaps.
Study library: every study we checked 17
| Study | Design | People | Product, dose, length | Result |
|---|---|---|---|---|
| Allwood 2021 Fermentation and the microbial community of Japanese koji and miso: A review. J Food Sci · PMID 34056716 · DOI |
Review n/a |
Review of koji and miso fermentation | Miso and koji |
The review describes miso as a traditional Japanese fermented food known mainly as the seasoning in miso soup. Making it takes two stages: a mould such as Aspergillus oryzae is grown on a substrate to make koji, and the koji is then added to a salt and soybean mash that ferments for up to 2 years. The authors say very little research has characterised the microbial process. Not applicable (Not applicable) Methods, limits and fundingOutcomes: Fermentation process, microbes, possible health benefits and food safety concerns Limitations: Only the abstract was read. The abstract says the review covers possible health benefits and food safety concerns but does not list them, so none are stated here. Funding and conflicts: Funding is not stated in the abstract. Read: abstract |
| Li 2026 Soy Foods Consumption and Multiple Health Outcomes: An Umbrella Review of Meta-Analyses. Mol Nutr Food Res · PMID 41327897 · DOI |
Umbrella review |
23 meta-analyses of observational studies (39 outcomes) and 1 meta-analysis of randomised trials (4 outcomes) | Soy foods in general, including fermented soy products Soy foods |
The authors conclude that soy food intake is more beneficial than harmful overall, especially for cancer and cardiometabolic diseases. They note that the benefits of fermented soy products were inconclusive, and that some studies indicated possible adverse effects. Not given in the abstract (Not given in the abstract) Methods, limits and fundingOutcomes: Health outcomes across soy food types Limitations: An overview of other reviews, mostly of observational studies. Miso is not named in the abstract. Funding and conflicts: Funding is not stated in the abstract. Read: abstract |
| Mah 2019 Bacterial Production and Control of Biogenic Amines in Asian Fermented Soybean Foods. Foods · PMID 30823593 · DOI |
Review n/a |
Review of Asian fermented soybean foods | Asian fermented soybean foods in general |
The amounts of biogenic amines in most products have been reported to be within safe levels, but certain products contain vasoactive biogenic amines above toxic levels. The authors say no government rules on biogenic amines in fermented soybean foods were found worldwide, and suggest starter cultures that do not make them. Not applicable (Not applicable) Methods, limits and fundingOutcomes: Biogenic amines in fermented soybean foods Limitations: Only the abstract was read. It does not say which products were high, and miso is not named in it. Funding and conflicts: Funding is not stated in the abstract. Read: abstract |
| Maleki Sedgi 2025 Effect of fermented soybean on metabolic outcomes, anthropometric indices, and body composition: a systematic review and meta-analysis of clinical trials. Food Funct · PMID 39763426 · DOI |
Systematic review meta analysis |
15 randomised controlled trials (searched to March 2024) | Fermented soy products (the abstract does not say which products or whether miso was among them) Fermented soy foods or products |
Compared with controls, fermented soy lowered BMI (-0.14 kg/m2), waist circumference (-1.50 cm), visceral fat (-692.17 mm2), fasting plasma glucose (-6.39 mg/dL) and total cholesterol (-5.0 mg/dL). The other measures did not change significantly. BMI -0.14 kg/m2; waist -1.50 cm; visceral fat -692.17 mm2; fasting glucose -6.39 mg/dL; total cholesterol -5.0 mg/dL (BMI -0.28 to -0.01; waist -2.94 to -0.07; visceral fat -1011.58 to -372.77; glucose -10.38 to -2.40; total cholesterol -6.60 to -3.39) Methods, limits and fundingOutcomes: BMI, waist circumference, visceral fat, fasting glucose, total cholesterol and other measures Limitations: Not specific to miso; the products tested are not named in the abstract. BMI and waist changes are very small and their intervals nearly reach zero. Only the abstract was read, so trial quality and differences between trials are not known. Funding and conflicts: Funding is not stated in the abstract. Read: abstract |
| Marco 2021 The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on fermented foods. Nat Rev Gastroenterol Hepatol · PMID 33398112 · DOI |
Consensus statement n/a |
Expert panel convened in September 2019 | Fermented foods and beverages in general |
The panel defined fermented foods and beverages as 'foods made through desired microbial growth and enzymatic conversions of food components', and separated them from probiotics. It also reviewed safety, risks and possible health benefits and a rationale for how fermented foods could improve gut and general health. Not applicable (Not applicable) Methods, limits and fundingOutcomes: Definition of fermented foods and how they differ from probiotics Limitations: An expert statement, not a trial. Miso is not named in the abstract. Several panel members report paid work with food, dairy and probiotic companies (conflict of interest statement in PubMed). Funding and conflicts: Several panel members declare consulting, speaking or grant income from food and probiotic companies. Read: abstract |
| Miyake 2025 Close adherence to the Japanese diet is not associated with a high prevalence of hypertension: the Japan Epidemiology Collaboration on Occupational Health Study. Br J Nutr · PMID 40222892 · DOI |
Cross sectional |
12213 12,213 employees of Japanese companies |
Traditional Japanese diet score of nine items (white rice, miso soup, soy products, vegetables, mushrooms, seaweeds, fish, salty food and green tea) Miso soup as one item in a score |
Across the four quarters of the traditional score, the prevalence ratios of hypertension were 1.00, 0.94, 0.98 and 0.96 (P for trend 0.29). A modified score showed a possible, non-significant inverse link (P for trend 0.10). Highest vs lowest quarter, traditional score: PR 0.96 (0.90 to 1.02) Methods, limits and fundingOutcomes: Prevalence of hypertension (140/90 mmHg or more, or blood pressure medicine) Limitations: A score of many foods; miso soup cannot be separated. Cross-sectional: it cannot show what came first. Hypertension was by measurement or medicine use. Funding and conflicts: Funding is not stated in the abstract. Read: abstract |
| Okamoto 2026 Consumption of salt and high-salt foods and the risks of oral, pharyngeal and oesophageal cancers: the JACC Study. Br J Nutr · PMID 40289732 · DOI |
Cohort study |
42535 42,535 Japanese adults aged 40 to 79, median follow-up 14.4 years (145 cancers: 43 oral, 17 pharyngeal, 85 oesophageal) |
Salt intake and high-salt foods by food frequency questionnaire, including miso soup Miso soup as one salt source |
High salt intake (highest vs lowest third) went with a higher risk of the three cancers combined (HR 1.67). Among salt sources, miso soup was positively associated with the combined risk, but other high-salt foods were not. Highest vs lowest third of salt: HR 1.67 (1.08 to 2.61 (P-trend 0.01)) Methods, limits and fundingOutcomes: Oral, pharyngeal and oesophageal cancers combined Limitations: The main finding is about total salt, not miso. The abstract gives no number for miso soup. Few cases (145). Food questionnaire done once in 1988 to 1990. Smoking and alcohol were adjusted for, but other causes can remain. Shows a link, not cause. Funding and conflicts: Funding is not stated in the abstract. Read: abstract |
| Saha Turna 2024 A review of biogenic amines in fermented foods: Occurrence and health effects. Heliyon · PMID 38304783 · DOI |
Review n/a |
Review of biogenic amines in fermented foods | Fermented foods in general |
Biogenic amines form during microbial fermentation. Several fermented foods may contain histamine, tyramine or phenylethylamine at levels above documented toxic doses. High intakes are linked with migraines, raised blood pressure and fast heartbeat. Toxicity can occur at levels a hundred times below suggested toxic doses, depending on a person's sensitivity, alcohol and certain medications. Not applicable (Not applicable) Methods, limits and fundingOutcomes: Biogenic amine levels (histamine, tyramine, phenylethylamine) and health effects Limitations: Only the abstract was read. Miso is not named in the abstract and no miso value was read. Funding and conflicts: Funding is not stated in the abstract. Read: abstract |
| Shibasaki 2025 Effect of Foods, Including Rice, Miso Soup, and Japanese Tea, on the Absorption of Zinc. J Nutr Sci Vitaminol (Tokyo) · PMID 41485970 · DOI |
Crossover pharmacokinetic |
13 13 healthy young volunteers |
Zinc acetate (25 mg zinc) taken fasting or with foods including 200 mL of miso soup Miso soup |
Serum zinc hardly rose when zinc was taken with brown rice, and was not reduced by seaweed soup. With the other foods, including miso soup, zinc absorption was reduced to 14 to 66% of the level with zinc alone. The abstract does not give a separate figure for miso soup. Zinc absorption with foods (other than seaweed soup) 14 to 66% of fasting (Not given in the abstract) Methods, limits and fundingOutcomes: Blood zinc levels over 4 hours (area under the curve) Limitations: Small study of 13 young volunteers using a zinc supplement. Not a study of zinc from food. The figure for miso soup alone is not in the abstract. Funding and conflicts: Funding is not stated in the abstract. Read: abstract |
| Ueba 2025 Dietary Patterns Rich in Soybean Products, Vegetables, Fish, Fruits, and Miso Soup Were Inversely Associated with Fatty Liver Index: The Nagahama Study. J Nutr Sci Vitaminol (Tokyo) · PMID 40024746 · DOI |
Cohort study |
3501 3,501 adults in a Japanese community cohort |
Dietary pattern rich in soybean products, vegetables, fish, fruits and miso soup (15-item food frequency questionnaire, factor analysis) Miso soup as one part of a pattern |
The pattern including miso soup was negatively correlated with FLI at baseline and with FLI after 5 years (partial regression coefficients -3.01 and -1.03, p<0.01 for both). The result was similar by sex and in people with BMI under 23 kg/m2. The authors suggest the pattern is protective against fatty liver disease, especially at BMI under 23. FLI coefficient -3.01 (baseline) and -1.03 (5 years) (Not given in the abstract) Methods, limits and fundingOutcomes: Fatty liver index (FLI) at baseline and after 5 years Limitations: A pattern of several foods; miso soup cannot be separated out. Self-reported questionnaire of only 15 food items. FLI is a formula, not a liver scan. Observational: shows a link, not cause. Funding and conflicts: Funding is not stated in the abstract. Read: abstract |
| Wang 2024 Soy Product Consumption and the Risk of Cancer: A Systematic Review and Meta-Analysis of Observational Studies. Nutrients · PMID 38613019 · DOI |
Systematic review meta analysis |
52 52 studies (17 cohort and 35 case-control) |
Soy products by type, including miso soup, soy paste, natto and tofu Soy products |
High intake of total soy products (RR 0.69), tofu (RR 0.78) and soymilk (RR 0.75) went with lower total cancer risk. No association was found for fermented soy products (RR 1.18, 95% CI 0.95 to 1.47), non-fermented soy products, soy paste (RR 1.00), miso soup (RR 0.99, 95% CI 0.87 to 1.12) or natto (RR 0.96). The authors call for more prospective cohorts to confirm cause. Miso soup RR 0.99; soy paste RR 1.00; fermented soy RR 1.18 (Miso soup 0.87 to 1.12; soy paste 0.88 to 1.14; fermented soy 0.95 to 1.47) Methods, limits and fundingOutcomes: Total cancer risk Limitations: Observational studies and many case-control studies, which can be biased by recall. Total cancer, not specific cancers. Shows a link, not cause. Funding and conflicts: Conflict of interest: none declared (per PubMed). Read: abstract |
| Wu 2021 Dietary Salt Intake and Gastric Cancer Risk: A Systematic Review and Meta-Analysis. Front Nutr · PMID 34957192 · DOI |
Systematic review meta analysis |
26 26 prospective cohort studies, 4,956,350 people, 19,301 gastric cancer cases |
Salt, pickled foods, salted fish, processed meat and miso soup intake Miso soup as one salt source |
High and moderate salt intake were linked with higher gastric cancer risk (RR 1.25 and 1.20). High pickled food and processed meat intake were also linked with higher risk. High (RR 1.04, 95% CI 0.90 to 1.19) and moderate (RR 1.02, 95% CI 0.94 to 1.11) miso soup intake had no significant effect on gastric cancer risk. Miso soup high RR 1.04; moderate RR 1.02; high salt RR 1.25 (Miso soup high 0.90 to 1.19; moderate 0.94 to 1.11; high salt 1.10 to 1.41) Methods, limits and fundingOutcomes: Gastric cancer morbidity and mortality Limitations: Observational cohorts; the studies were mostly of food questionnaires. Gastric cancer only. Shows a link, not cause. Funding and conflicts: Conflict of interest: none declared (per PubMed). Read: abstract |
| s-fda-allergens US FDA: Food Allergies · Source |
Health agency n/a |
Methods, limits and fundingRead: full-text | ||
| s-fda-sodium US FDA: Sodium in Your Diet · Source |
Health agency n/a |
Methods, limits and fundingRead: full-text | ||
| s-gbif-glycine-max GBIF Backbone: Glycine max (L.) Merr. (usageKey 5359660) · Source |
Reference database n/a |
Methods, limits and fundingRead: full-text | ||
| s-usda-fdc-172442 USDA FoodData Central: Miso (FDC 172442, SR Legacy, April 2018) · Source |
Reference database n/a |
Methods, limits and fundingRead: full-text | ||
| s-who-salt WHO: Sodium reduction (fact sheet) · Source |
Health agency n/a |
Methods, limits and fundingRead: full-text |
What we do not know yet
- No trial of miso on its own was found for any health outcome; results are for food patterns with miso soup or for fermented soy in general.
- The cancer cohort gives no number for miso soup in its abstract, and the cohorts are observational.
- No miso-specific tyramine or histamine value was read.
- Wheat or barley in miso made with other grains, gluten, kidney disease advice, thyroid, contamination and shelf life were not researched.
- No official statement on miso in pregnancy, breastfeeding or childhood was found.
- Whether live microbes in miso survive and matter for health was not shown. Only abstracts were read for studies.
How new research is added
New studies are found by a saved PubMed search and placed in a review queue before the page changes.
Lab markers
What changed in blood or saliva tests during trials. A changed number is not the same as feeling or being healthier, and we give no "normal ranges".
Metabolic 2
Fasting blood glucose
Lowered in trials
The sugar level in the blood after not eating overnight.
Low certaintyResults and what it means
Why it was measured
A basic marker of blood sugar control.
Statistical vs. clinical meaning
A small average fall for fermented soy in general, not shown for miso.
Safety implication
None specific.
| Study | Result | People | Product |
|---|---|---|---|
| 4 | -6.39 mg/dL (95% CI -10.38 to -2.40) versus controls | 15 randomised trials | Fermented soy products (types not named in the abstract) |
Total cholesterol
Lowered in trials
All the cholesterol carried in the blood.
Low certaintyResults and what it means
Why it was measured
A common blood marker in diet trials for heart risk.
Statistical vs. clinical meaning
A small average fall for fermented soy in general, not shown for miso.
Safety implication
None specific.
| Study | Result | People | Product |
|---|---|---|---|
| 4 | -5.0 mg/dL (95% CI -6.60 to -3.39) versus controls | 15 randomised trials | Fermented soy products (types not named in the abstract) |
Other 3
Fatty liver index (FLI)
Lowered (link) in trials
A score calculated from waist size, BMI, blood triglycerides and a liver enzyme, used to estimate the chance of fatty liver.
Very low certaintyResults and what it means
Why it was measured
To see whether an eating pattern goes with less liver fat.
Statistical vs. clinical meaning
A link in one cohort for a whole pattern; not shown for miso.
Safety implication
None specific; miso soup is salty.
| Study | Result | People | Product |
|---|---|---|---|
| 10 | Pattern with miso soup: coefficient -3.01 at baseline and -1.03 for FLI at 5 years (p<0.01) | 3,501 adults, Nagahama cohort | Food pattern rich in soybean products, vegetables, fish, fruits and miso soup (observed, not assigned) |
High blood pressure (prevalence)
No significant change in trials
Blood pressure of 140/90 mmHg or more, or use of blood pressure medicine.
Not enough evidenceResults and what it means
Why it was measured
To see whether a traditional diet that includes miso soup goes with more or less high blood pressure.
Statistical vs. clinical meaning
No clear link for a nine-food score; nothing specific to miso.
Safety implication
Miso has a lot of sodium, which guidance bodies link with raised blood pressure.
| Study | Result | People | Product |
|---|---|---|---|
| 6 | Prevalence ratio 0.96 (95% CI 0.90 to 1.02) for the highest vs lowest quarter of the traditional Japanese diet score; P for trend 0.29 | 12,213 employees of Japanese companies | Traditional Japanese diet score including miso soup (observed) |
Total cancer risk (pooled relative risk)
No significant change in trials
How much more or less likely cancer was in people who ate the most of a food versus the least.
Low certaintyResults and what it means
Why it was measured
To see whether eating miso soup or soy paste goes with more or less cancer.
Statistical vs. clinical meaning
No clear link for miso soup. Observational.
Safety implication
Salt is a separate concern in the cohorts.
| Study | Result | People | Product |
|---|---|---|---|
| 11 | Miso soup RR 0.99 (95% CI 0.87 to 1.12); soy paste RR 1.00 (0.88 to 1.14); fermented soy products RR 1.18 (0.95 to 1.47) | 52 observational studies (17 cohort, 35 case-control) | Highest vs lowest intake (observed) |
Safety
What studies and official sources say about side effects, medicines and who should check first. Each point shows what kind of evidence it comes from.
Main points to know 4
- Miso is very salty. USDA lists 3,728 mg of sodium per 100 g of miso, about 634 mg in a tablespoon (17 g). The FDA says diets higher in sodium are associated with a higher risk of high blood pressure, a major cause of stroke and heart disease, and gives a Daily Value of less than 2,300 mg a day. WHO recommends adults take in less than 2,000 mg of sodium a day. Brands and types differ, so check the label. If you have high blood pressure, heart or kidney disease, or have been told to limit salt, ask your clinician or dietitian how miso fits. Authoritative guidance 16 14 17
- Soy allergy. Miso is made from soybeans, and the US FDA lists soybeans among the nine major food allergens. Reactions range from mild to life-threatening. If you have a soy allergy, miso is not safe for you. Some misos are made with other grains; whether they add wheat or barley allergens was not researched, so read the label. Authoritative guidance 13
- MAOI antidepressants and fermented foods. A 2024 review says several fermented foods may contain tyramine or histamine above documented toxic doses, that eating them is linked with migraines, raised blood pressure and fast heartbeat, and that certain medicines make this more likely. A 2019 review says most Asian fermented soybean products are within safe levels but some are above toxic levels. Neither abstract names miso, and no miso-specific value was read. If you take an MAOI, ask your prescriber or pharmacist about miso. Review 8 3
- Salt and some cancers. In one large Japanese cohort, high salt intake went with a higher risk of mouth, throat and oesophagus cancers, and miso soup was among the salt sources linked with it. Two pooled analyses found no link between miso soup and total cancer or gastric cancer, although high salt intake itself was linked with gastric cancer. These are observational and show links, not cause. Observational 7 11 12
Side effects 3
| Effect | How often | Severity and recovery | Evidence |
|---|---|---|---|
| Allergic reactions to soy, from itching and hives to anaphylaxis The FDA page names soybeans as a major allergen; it does not give a figure for miso. | No miso-specific figure was read | can be severe (anaphylaxis) Not described in the sources read. | Authoritative guidance 13 |
| Headache, raised blood pressure or fast heartbeat from biogenic amines (tyramine, histamine) in some fermented foods General to fermented foods. Miso is not named in either abstract. | No miso-specific frequency was read | mild to serious, depending on the person, medicines and alcohol Not described. | Review 8 3 |
| Higher sodium intake and, over time, raised blood pressure A diet-level effect of total sodium, not a finding that miso alone raises blood pressure. | Not applicable | depends on total salt in the diet Not described. | Authoritative guidance 14 17 |
Liver
No liver injury from eating miso was found in the sources read. A liver-safety source such as LiverTox was not searched for miso.
How often. No frequency was found.
Monitoring. No agency monitoring advice was found.
This is a safety connection. It is not evidence that Miso supports liver health.
Medicines and supplements 4
| With | Why it matters | Importance | Evidence | What to do |
|---|---|---|---|---|
| MAOI antidepressants (monoamine oxidase inhibitors) prescription | Tyramine and other biogenic amines form during fermentation. With an MAOI, tyramine can raise blood pressure. | Reviews say some fermented foods have amine levels above toxic doses and that medicines raise the risk, and that most Asian fermented soybean products are within safe levels. No miso value was read, so the size of any risk from miso is not known. | Review Not enough evidence 8 3 | Ask your prescriber or pharmacist before eating miso on an MAOI. |
| Zinc supplements supplement | Foods eaten with a zinc tablet can reduce how much zinc is absorbed. | In 13 healthy volunteers who took 25 mg of zinc as zinc acetate, absorption with most foods, including a 200 mL bowl of miso soup, was 14 to 66% of that with zinc alone. The abstract gives no separate figure for miso soup. This was a zinc supplement, not zinc from food. | Small human study Low certainty 9 | If you take zinc tablets, ask your pharmacist whether to take them with or apart from meals. |
| Warfarin (vitamin K) prescription | Miso contains some vitamin K (USDA: 29.3 micrograms per 100 g, about 5 micrograms in a tablespoon), and vitamin K can work against warfarin. | No source read names miso with warfarin. This is a general caution from the nutrient value, not a documented interaction. | Theoretical Not enough evidence 16 | Tell your anticoagulation clinic about large changes in your diet. |
| Medicines for blood pressure, heart failure or kidney disease prescription | Sodium from food can work against blood pressure control. | No source read tested miso with these medicines. This follows from the general statement that diets higher in sodium are linked with higher blood pressure. | Authoritative guidance Not enough evidence 14 17 | Ask your clinician or dietitian about your own salt limit. |
Who should check first 4
| Situation | Advice | Evidence |
|---|---|---|
| Known or suspected soy allergy | Avoid miso and other soy foods and read labels. Ask an allergist about your own case. For trouble breathing or swelling of the face, lips or throat, call 911 or your local emergency number. | Authoritative guidance 13 |
| High blood pressure, heart or kidney disease, or a salt limit set by your clinician | Miso is a high-sodium food by USDA data. Ask your clinician or dietitian how it fits your limit. No miso-specific kidney or heart advice was read. | Authoritative guidance 16 14 17 |
| Taking an MAOI antidepressant | Ask your prescriber or pharmacist about miso and other fermented foods before eating them. | Review 8 3 |
| Pregnancy, breastfeeding, babies and children | No official statement on miso in pregnancy, breastfeeding or childhood was found in the sources read. The FDA notes lower sodium limits for children under 14. Ask your midwife, doctor or dietitian. | Not found 14 |
Overdose, product quality and regulators
Summary. No toxicity from miso as an ordinary seasoning was found in the sources read. The safety points are salt, soy allergy and the amine question for people on MAOIs.
Animal. Not reviewed.
High dose or long term signals. The cohort and salt findings are about long-term high salt intake overall.
Overdose response. Not found.
Genotoxicity. Not researched.
Contamination of miso (mould toxins, heavy metals, pesticides) and its shelf life were not researched. The 2021 review of koji and miso says it covers food safety concerns, but its abstract does not list them.
Biogenic amines. Biogenic amines form during microbial fermentation, and a 2019 review says some Asian fermented soybean products contain vasoactive amines above toxic levels. Miso is not named in the abstract. 3 8
| Body | Action | Date |
|---|---|---|
| US FDA (United States) | Food Allergies: soybeans are one of the nine major food allergens identified by law in the US. source | 2026-03-11 |
| US FDA (United States) | Sodium in Your Diet: higher sodium is associated with a higher risk of high blood pressure; the Daily Value is less than 2,300 mg a day; lower limits for children under 14. source | 2024-03-05 |
| World Health Organization (International) | Sodium reduction fact sheet: recommends adults take in less than 2,000 mg of sodium a day (less than 5 g salt); high sodium raises blood pressure and the risk of cardiovascular disease, gastric cancer and other conditions. source | 2026-05-11 |
When to get medical help
- Trouble breathing, wheezing, swelling of the lips, face, tongue or throat, widespread hives, repeated vomiting, dizziness or collapse after eating miso or another soy food (possible anaphylaxis): use epinephrine if prescribed, then call 911 or your local emergency number
- Severe headache, pounding heartbeat or very high blood pressure after eating a fermented food while taking an MAOI: seek urgent medical help
Stop using the product and contact a clinician or emergency service. In the US, Poison Control is 1-800-222-1222.
General information only, not medical advice. Ask a clinician or pharmacist before use, especially with medicines, in pregnancy or with a health condition. See the Natural Remedy Safety guide.
Frequently asked questions
What is miso?
Miso is a traditional Japanese paste made by fermenting soybeans with salt and koji, a mould grown on a base such as grain or beans. It is used mainly as a seasoning, especially in miso soup.
What is in miso nutritionally?
By USDA data, miso has 12.79 g of protein, 5.4 g of fibre, 2.56 mg of zinc and 0.859 mg of manganese per 100 g. A tablespoon (17 g) has about 34 kcal and 2.2 g of protein. Real products differ, so read the label.
How much sodium is in miso?
Is miso healthy?
Is miso a probiotic?
Can I eat miso if I have a soy allergy?
Miso is made from soybeans, and soybeans are a major food allergen in the US. If you have a soy allergy, avoid it and ask your allergist. For trouble breathing or swelling of the face or throat, call 911 or your local emergency number.
Is miso safe with an MAOI antidepressant?
Does miso cause or prevent cancer?
Does miso help the liver?
Not shown for miso itself. In one Japanese cohort, a food pattern that included miso soup went with a lower fatty liver index, but miso soup could not be separated from the other foods.
Does miso lower blood sugar or cholesterol?
Is miso bad for blood pressure?
Miso is very high in sodium, and the FDA and WHO link high sodium intake with higher blood pressure. A study of 12,213 Japanese workers found no link between a diet score that includes miso soup and high blood pressure. If you have high blood pressure, ask your clinician about your salt limit.
Is miso safe in pregnancy or breastfeeding?
No official statement on miso in pregnancy, breastfeeding or childhood was found in the sources read. Ask your midwife, doctor or dietitian.
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Editorial transparency
- Written by
- AlternativeMed editorial team. Research compiled with AI assistance, then checked against the sources listed.
- Medical review
- None. This page has not been reviewed by a physician or pharmacist.
- First published
- 2026-10-26
- Last substantive update
- 2026-10-26
- How we research
- We started from our existing miso summary and its reference list, re-checked nutrition against saved USDA FoodData Central data, re-read the FDA and WHO sodium pages and the FDA allergy page, and re-read PubMed abstracts for each study. Two pooled analyses reporting miso soup were added from a new search. Only abstracts were read for studies. Items we could not verify are flagged in the research gaps.
- How we rate evidence
- See "How we rate evidence" in the Evidence tab.
- Independence
- No product is promoted on this page. No affiliate links are shown. The expert statement on fermented foods lists paid work for food and probiotic companies by several panel members; this is noted where it is used.
Sources 17
Each source was opened and checked. Where we read only the abstract, it says so. The small numbers in the text point here.
- Allwood JG, Wakeling LT, Bean DC. Fermentation and the microbial community of Japanese koji and miso: A review.. J Food Sci. 2021. PMID 34056716. DOI 10.1111/1750-3841.15773. (abstract)
- Li W, Wei X, Zhang J, et al.. Soy Foods Consumption and Multiple Health Outcomes: An Umbrella Review of Meta-Analyses.. Mol Nutr Food Res. 2026. PMID 41327897. DOI 10.1002/mnfr.70255. (abstract)
- Mah JH, Park YK, Jin YH, et al.. Bacterial Production and Control of Biogenic Amines in Asian Fermented Soybean Foods.. Foods. 2019. PMID 30823593. DOI 10.3390/foods8020085. (abstract)
- Maleki Sedgi F, Mozaffari N, Pashaei MR, Hajizadeh-Sharafabad F. Effect of fermented soybean on metabolic outcomes, anthropometric indices, and body composition: a systematic review and meta-analysis of clinical trials.. Food Funct. 2025. PMID 39763426. DOI 10.1039/d4fo02668c. (abstract)
- Marco ML, Sanders ME, Gänzle M, et al.. The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on fermented foods.. Nat Rev Gastroenterol Hepatol. 2021. PMID 33398112. DOI 10.1038/s41575-020-00390-5. (abstract)
- Miyake H, Nanri A, Okazaki H, et al.. Close adherence to the Japanese diet is not associated with a high prevalence of hypertension: the Japan Epidemiology Collaboration on Occupational Health Study.. Br J Nutr. 2025. PMID 40222892. DOI 10.1017/S0007114525000844. (abstract)
- Okamoto K, Eshak ES, Muraki I, et al.. Consumption of salt and high-salt foods and the risks of oral, pharyngeal and oesophageal cancers: the JACC Study.. Br J Nutr. 2026. PMID 40289732. DOI 10.1017/S000711452500056X. (abstract)
- Saha Turna N, Chung R, McIntyre L. A review of biogenic amines in fermented foods: Occurrence and health effects.. Heliyon. 2024. PMID 38304783. DOI 10.1016/j.heliyon.2024.e24501. (abstract)
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- . US FDA: Food Allergies. . . (full-text)
- . US FDA: Sodium in Your Diet. . . (full-text)
- . GBIF Backbone: Glycine max (L.) Merr. (usageKey 5359660). . . (full-text)
- . USDA FoodData Central: Miso (FDC 172442, SR Legacy, April 2018). . . (full-text)
- . WHO: Sodium reduction (fact sheet). . . (full-text)
