Miso: a heavy salt carrier with mixed evidence on blood pressure and cancer

In a randomized trial on 187 Japanese men with high-normal or raised blood pressure who were not taking blood pressure medicines, switching to miso soup and a boxed lunch made with low-sodium, high-potassium seasonings lowered systolic pressure by 2.1 mmHg (95% CI 0.6 to 3.6). Soup and lunch changed together, so the effect cannot be pinned on the soup. Those seasonings were the trial's test food, not advice to swap salt for potassium, and we hold no card on potassium-rich seasonings for people on blood pressure medicines or with kidney disease. The salt in miso is real. USDA lists 3,728 mg of sodium per 3.5 oz (100 g), 162% of the Daily Value, from one record, and white, red and reduced-salt misos differ widely. A cup of miso soup in the US survey database carries about 1,144 mg. In 40 adults with high-normal or mildly raised pressure, a trial gave two bowls a day for 8 weeks, with 3.8 g of salt. Daytime blood pressure did not rise against a low-salt soy food, and night-time pressure came out lower, but that salt still counted toward each day's total. That trial was small, used one maker's specially chosen misos, and its abstract gives no effect size.

The numbers, per 3.5 oz (100 g)

As people eat it, per 3.5 oz (100 g)

How much is actually in it

• Miso is mostly a salt carrier: USDA lists 3,728 mg of sodium per 3.5 oz (100 g), 162% of the Daily Value, alongside 12.8 g of protein. — USDA SR Legacy record for Miso (n = 1 record) Evidence E source
  Sodium 3728 mg per 3.5 oz (100 g) (162% DV); copper 0.42 mg (47% DV); protein 12.79 g (26% DV)

What a real portion looks like

• A cup of miso soup in the US food survey database carries about 1,144 mg of sodium, and the usual unspecified amount of miso paste is counted as 12 g. — USDA FNDDS records Miso (41420110, FDC 2707439) and Soup, miso or tofu (FDC 2707455) (n = 2 records) Evidence E source
  Miso soup sodium 467 mg per 3.5 oz (100 g), 1144.2 mg per 245 g cup; miso paste quantity not specified 12 g, 1 cup 275 g

What your body absorbs

• Fermentation changes how soy isoflavones are absorbed: tempeh, rich in the fermented aglycone form, gave higher blood peaks of daidzein and genistein than unfermented soy protein in 59 adults. — 59 healthy adults (21 premenopausal women, 17 postmenopausal women, 21 men), randomized crossover of soy milk, textured vegetable protein and tempeh at 0.44 mg isoflavones per kg (n = 59) Evidence B source
  Tempeh gave higher serum peak daidzein (P < 0.001) and genistein (P < 0.01) and higher AUC than textured vegetable protein; soy milk absorbed fastest
• The fermented-is-better-absorbed idea has limits: in 16 postmenopausal women, fermented soy milk with far more aglycones did not raise total isoflavone excretion, which stayed near 31% of intake. — 16 postmenopausal women, double-blind crossover of fermented or non-fermented soy milk at 20, 40 and 80 mg isoflavones, three 14-day periods (n = 16) Evidence B source
  Aglycone share 36-69% fermented vs 7-10% non-fermented; total urinary isoflavone excretion similar, recovery about 31%

What it does to your health

• Swapping to low-sodium, high-potassium miso soup and lunch lowered systolic blood pressure by 2.1 mmHg in 187 Japanese men not on medication. — 187 Japanese men aged 35 to 67 with high-normal or raised blood pressure, not on antihypertensives, given boxed lunches and instant miso soup made with low-sodium, high-potassium seasonings or regular ones (n = 187) Evidence B source
  Systolic blood pressure change -2.1 mmHg (95% CI -3.6 to -0.6) versus control; meal sodium 1175 vs 2243 mg, potassium 1476 vs 703 mg

Safety, limits and interactions

• In 527 Japanese adults aged 50 to 81, how often they drank miso soup was not linked to blood pressure or hypertension, though frequent drinkers had lower heart rates. — 527 people aged 50 to 81 at a Japanese hospital health examination, grouped from under one to seven or more bowls of miso soup a week (n = 527) Evidence C source
  No association between miso soup frequency and blood pressure or hypertension; lower heart rate with higher frequency
• In a Japanese cohort of 42,535 adults followed for about 14 years, miso soup was the one salty food linked to higher risk of mouth, throat and esophageal cancers. — 42,535 Japanese adults aged 40 to 79 in the JACC Study, food frequency questionnaire 1988-1990, median follow-up 14.4 years, 145 cases (n = 42535) Evidence C source
  Highest vs lowest salt tertile HR 1.67 (95% CI 1.08 to 2.61); miso soup positively associated with combined oral, pharyngeal and esophageal cancer, other high-salt foods not
• The FDA label for transdermal selegiline (EMSAM) at 9 mg/24 h or more puts most soybean products on the tyramine avoid list, naming soy sauce and tofu. Miso is a soybean product but is not named. — Adults using EMSAM (selegiline transdermal system) at 9 mg/24 h or 12 mg/24 h (n = -) Evidence E source
  Avoid list in label Table 5, miscellaneous class

What people believe that the data does not support

• Miso is often sold as a longevity food, but a 2026 pooling of 50 cohort studies with more than three million people found no link between miso and death from any cause, heart disease or cancer. — 50 prospective cohort studies, more than three million healthy adults, fermented foods and all-cause, cardiovascular and cancer mortality Evidence C source
  Miso not significantly associated with mortality; cheese, fermented milks and chocolate associated with lower all-cause and cardiovascular mortality

Who this works differently for

• Two bowls of miso soup a day for 8 weeks, carrying 3.8 g of salt, did not raise daytime blood pressure and lowered night-time blood pressure against a low-salt soy food in 40 adults with high-normal pressure or stage I hypertension. — 40 men and women aged 40 to 69 with high-normal blood pressure or untreated stage I hypertension, randomized double-blind to 1.1 oz (32 g) of miso a day (3.8 g salt) or soy food (0.2 g salt) for 8 weeks (n = 40) Evidence B source
  No change in daytime clinical blood pressure; night-time blood pressure significantly lower with miso than soy food; no effect on lipids or glucose
• Across 13 prospective studies with 517,106 people, men with high miso soup intake had a 17% higher relative risk of gastric cancer, while non-fermented soy foods went the other way. — 517,106 participants and 5,800 gastric cancer cases in 13 prospective studies, 10 of them in Japan (n = 517106) Evidence C source
  Miso soup in men RR 1.17 (95% CI 1.02 to 1.36); total soy food RR 0.78 (0.62 to 0.98); non-fermented soy RR 0.63 (0.50 to 0.79)
• An older pooling of 28 studies found miso eaters had 18% higher odds of gastric cancer, while soy foods overall were tied to 42% lower odds. — 28 studies on soy products and gastric cancer (16 case-control, 10 cohort, 2 cross-sectional), English and Chinese literature 1988-2008 Evidence C source
  Miso OR 1.18 (95% CI 1.09 to 1.28); soybean products OR 0.58 (0.52 to 0.65); tofu OR 0.90 (0.80 to 1.00)
• Miso is still soy for children with soy food allergy syndromes: a 20-month-old with Down syndrome and soy-induced FPIES reacted after eating miso and green peas at home. — One 20-month-old girl with Down syndrome and severe milk- and soy-induced food protein-induced enterocolitis syndrome (n = 1) Evidence D source
  FPIES symptoms after ingesting green peas and miso at home; soy-based seasoning had been tolerated in hospital

What is still unknown

• Miso soup showed no link with total cancer risk in a 2024 pooling of 52 observational studies, unlike tofu and soy milk, which were tied to lower risk. — 52 observational studies (17 cohort, 35 case-control) on soy products and cancer, searched to October 2023 Evidence C source
  Miso soup RR 0.99 (95% CI 0.87 to 1.12); soy paste RR 1.00 (0.88 to 1.14); tofu RR 0.78 (0.70 to 0.86); soy milk RR 0.75 (0.60 to 0.93)

The bottom line

Miso is often sold as a longevity food. A 2026 pooling of 50 cohort studies with more than three million adults found no link between miso and death from any cause, heart disease or cancer. Across 52 observational studies, miso soup showed no link with total cancer risk either (relative risk 0.99, 95% CI 0.87 to 1.12), while tofu and soy milk were tied to lower risk. That total can hide signals at single sites, and the stomach is where the data disagree. In 13 prospective studies of 517,106 people, men with high miso soup intake had a relative risk of gastric cancer of 1.17 (95% CI 1.02 to 1.36). Non-fermented soy went the other way. An older pooling of 28 studies put the odds for miso at 1.18. These are associations from food questionnaires, the higher risk was seen in men, and miso travels with salt, so the signal may belong to the salt. Fermentation changes the form of soy isoflavones. Tempeh, mostly the fermented form, gave higher blood peaks than unfermented soy protein in 59 adults. Fermented soy milk did not raise total isoflavone excretion in 16 postmenopausal women. Neither study used miso, and neither measured a health outcome. Cautions sit mostly with salt. In a Japanese cohort of 42,535 adults followed about 14 years, miso soup was the one salty food associated with mouth, throat and esophageal cancers. That rests on 145 cases, and hot soup is a competing explanation. In 527 Japanese adults aged 50 to 81, how often they drank miso soup was not linked to blood pressure, though that was a single-hospital snapshot and people with high blood pressure may already have cut back. Miso is still soy for a child with soy allergy syndromes. A 20-month-old with soy-induced FPIES reacted after eating miso and green peas at home, though which food caused it was not tested. We have no card on miso in pregnancy or alongside medicines, so nothing on this page shows that daily miso is safe with any medicine. If you take regular prescription medicines, ask the prescriber before making miso a daily habit.

Sources

1. miso-r3-01 · USDA FoodData Central SR Legacy, dataset
   Miso (FDC 172442, SR Legacy, Legumes and Legume Products): sodium 3728 mg per 100 g = 162% DV; copper 0.42 mg = 47% DV; protein 12.79 g = 26% DV; Foundation samples 0, CoFID match none
   USDA FoodData Central, SR Legacy, FDC 172442 · checked 2026-09-28
2. miso-r3-02 · USDA FNDDS portion weights and nutrient values, dataset
   Miso (FNDDS 41420110, FDC 2707439): 1 cup 275 g; Quantity not specified 12 g. Soup, miso or tofu (FDC 2707455): Sodium, Na 467 MG per 100 g; 1 cup 245 g = 1144.2 MG
   USDA FNDDS 2021-2023, food code 41420110 (FDC 2707439) and FDC 2707455 · checked 2026-09-28
3. miso-r3-11 · randomized crossover trial in humans
   Consumption of tempeh (mainly isoflavone aglycon) resulted in higher serum peak levels of both daidzein (P < 0.001) and genistein (P < 0.01) and the associated area under the curve (P < 0.001 and P < 0.03, respectively) compared with textured vegetable protein (predominantly isoflavone glucosides).
   J Nutr, 2006 · checked 2026-09-28
4. miso-r3-12 · randomized crossover trial in humans
   However, total urinary isoflavone excretion was similar for both groups (P>0.05), with urinary isoflavone recovery at approximately 31 %.
   Br J Nutr, 2005 · checked 2026-09-28
5. miso-r3-04 · randomized controlled trial in humans
   They were given a boxed lunch and miso soup (average Na and K content for the intervention group: 1175 and 1476 mg; for the control group: 2243 and 703 mg, respectively). ... The mean difference in systolic blood pressure change after adjustment for baseline values between the two groups was -2.1 (95% CI: -3.6, -0.6) mmHg.
   Nutrients, 2021 · checked 2026-09-28
6. miso-r3-05 · cross-sectional study in humans
   Results The frequency of miso soup consumption was not associated with blood pressure. The heart rate was, however, lower in the participants who reported a high frequency of miso soup consumption.
   Intern Med, 2017 · checked 2026-09-28
7. miso-r3-08 · cohort study in humans
   Among the salt sources, miso soup consumption was positively associated with the combined risk of oral, pharyngeal and oesophageal cancers; however, the consumption of other high-salt foods was not.
   Br J Nutr, 2026 · checked 2026-09-28
8. sf-tymaoi-10 · agency advice
   Concentrated yeast extract (e.g., Marmite), sauerkraut, most soybean products (including soy sauce and tofu)
   EMSAM (selegiline transdermal system), FDA-approved label, sections 2.3 and 7.2 (Table 5) · checked 2026-10-08
9. miso-r3-09 · meta-analysis of cohort studies
   Miso and bread consumption showed no significant associations with mortality.
   Front Nutr, 2026 · checked 2026-09-28
10. miso-r3-03 · randomized controlled trial in humans
    A total of 40 subjects aged 40-69 years with high-normal BP or stage I hypertension were randomly assigned to two groups: 1) the miso group (32 g 2:1 w/w Nenrin and MK-34-1 with 3.8 g salt/day) or 2) the control soy food group (14.4 g soy food with 0.2 g salt/day). ... Compared with the soy food intake, miso intake for 8 weeks did not affect daytime clinical BP but significantly decreased nighttime BP without affecting pulse rate (PR).
    Hypertens Res, 2019 · checked 2026-09-28
11. miso-r3-06 · meta-analysis of cohort studies
    Among 11 types of soy food, high intake of total soy food (the highest vs the lowest category: RR: 0.78, 95% CI: 0.62-0.98) and nonfermented soy food (RR: 0.63, 95% CI: 0.50-0.79) were inversely associated with GC risk, while high intake of miso soup was associated with the risk in male (RR: 1.17, 95% CI: 1.02-1.36).
    Medicine (Baltimore), 2017 · checked 2026-09-28
12. miso-r3-10 · meta-analysis of observational studies
    The overall ORs (95%CI) of Meta-analysis on subjects who consumed soybean products, tofu and miso were 0.58 (0.52 - 0.65), 0.90 (0.80 - 1.00) and 1.18 (1.09 - 1.28), respectively.
    Zhonghua Yu Fang Yi Xue Za Zhi, 2010 · checked 2026-09-28
13. miso-r3-13 · case report in humans
    After discharge, she exhibited an FPIES symptom as a consequence of ingesting green peas and miso; hence, we recommended the elimination of peas, in addition to soy, milk, and egg yolk, from her diet.
    JMA J, 2025 · checked 2026-09-28
14. miso-r3-07 · meta-analysis of cohort and case-control studies
    No association was found between high consumption of fermented soy products (RR: 1.18; 95% CI: 0.95, 1.47), non-fermented soy products (RR: 0.95; 95% CI: 0.77, 1.18), soy paste (RR: 1.00; 95% CI: 0.88, 1.14), miso soup (RR: 0.99; 95% CI: 0.87, 1.12), or natto (RR: 0.96; 95% CI: 0.82, 1.11) and cancer risk.
    Nutrients, 2024 · checked 2026-09-28