Soybeans fermented with Aspergillus oryzae koji, salt and usually a grain, for anywhere from weeks to years. Longer ferments darken it and deepen the flavour as proteins break down into free amino acids.
Ordered by how well the human research supports them — strongest first. A rating describes the state of the evidence, not how impressive the food is. How we rate evidence.
Observational data links fermented soy intake with lower cardiovascular mortality in Japanese cohorts. These findings are hard to separate from the wider dietary pattern they sit in and have not been tested in trials.
Insufficient evidence. Not enough human research to say anything useful yet.
Evidence is limited for miso affecting the gut microbiome. Human trials measuring microbial outcomes after miso intake are essentially absent, and most miso is heated before it is eaten.
Insufficient evidence. Not enough human research to say anything useful yet.
Observational data from Japan does not show the rise in blood pressure that miso sodium content alone would predict, and a few small trials report neutral or slightly favourable effects. The evidence is thin and does not license treating miso as low-sodium.
Insufficient evidence. Not enough human research to say anything useful yet.
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| Nutrient | Amount | % DV |
|---|---|---|
| Macronutrients | ||
| Calories | 198 kcal | 10% |
| Protein | 12.8 g | 26% |
| Total fat | 6.01 g | 8% |
| Carbohydrate | 25.4 g | 9% |
| Fibre | 5.4 g | 19% |
| Total sugars | 6.2 g | — |
| Water | 43 g | — |
| Fats | ||
| Saturated fat | 1.02 g | 5% |
| Monounsaturated fat | 1.12 g | — |
| Polyunsaturated fat | 2.88 g | — |
| Cholesterol | 0 mg | 0% |
| EPA (omega-3) | 0 g | — |
| DHA (omega-3) | 0 g | — |
| DPA (omega-3) | 0 g | — |
| Linoleic acid (omega-6) | 2.48 g | — |
| Vitamins | ||
| Vitamin A | 4 µg | 0% |
| Vitamin C | 0 mg | 0% |
| Vitamin D | 0 µg | 0% |
| Vitamin E | 0.01 mg | 0% |
| Vitamin K | 29.3 µg | 24% |
| Thiamin (B1) | 0.098 mg | 8% |
| Riboflavin (B2) | 0.233 mg | 18% |
| Niacin (B3) | 0.906 mg | 6% |
| Pantothenic acid (B5) | 0.337 mg | 7% |
| Vitamin B6 | 0.199 mg | 12% |
| Folate | 19 µg | 5% |
| Vitamin B12 | 0.08 µg | 3% |
| Choline | 72.2 mg | 13% |
| Minerals | ||
| Calcium | 57 mg | 4% |
| Iron | 2.49 mg | 14% |
| Magnesium | 48 mg | 11% |
| Phosphorus | 159 mg | 13% |
| Potassium | 210 mg | 4% |
| Sodium | 3728 mg | 162% |
| Zinc | 2.56 mg | 23% |
| Copper | 0.42 mg | 47% |
| Manganese | 0.859 mg | 37% |
| Selenium | 7 µg | 13% |
| Other measured compounds | ||
| Beta-carotene | 52 µg | — |
| Alpha-carotene | 0 µg | — |
| Lycopene | 0 µg | — |
| Lutein + zeaxanthin | 0 µg | — |
| Caffeine | 0 mg | — |
| Ash | 12.8 g | — |
Nutrient values are per 100 g of the USDA reference entry named on this page and vary with variety, growing conditions, storage and preparation.
Source record: Miso (USDA FoodData Central, FDC ID 172442).
% DV uses the FDA Daily Values for adults and children aged 4 and over. A dash means no Daily Value has been established for that nutrient.
Compounds present in meaningful amounts. Presence is banded rather than quantified, because whole-food levels vary enormously with variety, growing conditions, storage and preparation.
Phytoestrogen
Soy phytoestrogens that bind oestrogen receptors far more weakly than oestradiol and with a preference for the beta receptor. Only some people…
Fermentation converts much of the soy isoflavone content to the aglycone form.
Microorganism
Live microorganisms present in unpasteurised fermented foods. Health effects in research are strain-specific, so a food containing live cultures is…
Unpasteurised miso contains live organisms; most is destroyed if it is boiled in soup.
Only effects with real support are listed. If a preparation method is missing, it is because nothing dependable is documented — not because it makes no difference.
Adding miso to boiling stock kills the live organisms and drives off aroma compounds, which is why it is traditionally stirred in off the heat.
Fermentation hydrolyses isoflavone glycosides to aglycones, which are absorbed faster and more completely than the forms in unfermented soy.
Allergies, interactions and intake concerns. Every food gets this section — a reference where everything is uniformly good is not a reference.
Too much
Salt is what keeps miso stable through a long fermentation, and it is among the saltiest foods in ordinary use. Portions are small, but miso soup drunk daily is a meaningful sodium source.
Allergy
Soy is a major regulated allergen. Many misos are made with barley or wheat koji, so they are not automatically gluten-free either.
Interaction
Long-fermented soy products accumulate tyramine and are on restriction lists for people taking non-selective monoamine oxidase inhibitors.
Worth knowing
Soy isoflavones can interfere with absorption of levothyroxine when eaten close to the dose. The usual advice is to separate them in time rather than to avoid soy.