Miso soup, salt and blood pressure in Japanese diets
What it found
In animal studies, miso lessened salt's effect on blood pressure and heart rate, and in people who often ate miso soup, heart rate was lower.
Human data on blood pressure are still inadequate.
What they found
Studies in people
Blood pressure in people
Two daily servings of miso soup for 3 months did not change blood pressure in people with normal blood pressure or stage I hypertension. Observational studies found no link between how often people ate miso soup and their blood pressure or rate of high blood pressure.
Heart rate in people
People who ate miso soup often had lower heart rates than those who ate it less. In winter, people who rarely ate miso soup had higher heart rates than in other seasons, but frequent eaters did not.
Animal and lab studies
Blood pressure in animals
In salt-sensitive rats, habitual miso soup intake weakened the rise in blood pressure from salt. One study found the drop reached 35 mmHg, and another estimated the effect matched a 30% cut in salt loading.
Nerve activity in animals
In mice with pressure overload, miso soup lowered a urine marker of sympathetic nerve activity and lowered heart rate compared with high-salt water (499 vs 535 beats per minute). In normal mice, injected miso liquid lowered blood pressure and nerve activity.
Brain effects in animals
When high-salt fluid was infused into the brains of mice, blood pressure and heart rate rose less if the mice had first been given diluted miso liquid. This suggests miso ingredients act in the brain.
Possible mechanism
Miso is a fermented soybean product. Small peptides in it may block an enzyme called ACE, and miso may also reduce oxidative stress in the brain, both of which could lower nerve activity.
What the authors conclude
“The intake of miso soup does not increase blood pressure and heart rate compared with the equivalent intake of salt, probably in part due to the lowering of SNA.”
Also in their conclusions
- They say the intake of miso soup does not increase blood pressure and heart rate compared with the equivalent intake of salt, probably in part due to the lowering of sympathetic nerve activity.
- They note that data are inadequate to conclude the effects of miso on blood pressure and heart rate in humans.
- They call for interventional studies to establish the effects of miso on blood pressure and heart rate in people.
How it was done
Japanese people eat more salt than Westerners, and miso soup is a major source. Since salt is needed to make miso, some people are told to cut back on miso soup to reduce salt. The authors wanted to see whether miso affects blood pressure and heart rate differently from the same amount of plain salt.
They reviewed basic animal studies and clinical studies in people on miso intake, salt intake, sympathetic nerve activity, blood pressure and heart rate. The animal work included salt-sensitive rats and mice, and mice with pressure overload from aortic banding. The human work included a 3-month trial of two daily servings of miso soup in people with normal blood pressure or stage I hypertension, and observational studies of how often people ate miso soup.
What it can’t tell you
- The animal results cannot be directly applied to people.
- The human studies mostly followed people over time or asked about habits, so they can show links, not cause and effect.
- People who often eat miso soup may also eat more vegetables, seaweed and fish, so the benefits seen may come from other foods too.
Who paid
- Conflicts
- The author declares no competing interests.
- Authors work at
- Kyushu Hospital, Japan
The paper
- Title
- Review of the health benefits of habitual consumption of miso soup: focus on the effects on sympathetic nerve activity, blood pressure, and heart rate
- Type
- ReviewThe authors read earlier studies and describe what they found. It isn’t a new study.
- Evidence
- Studies in people · animals · lab
- Summarised from
- Full text
- Licence
- CC BY. Words in quotation marks are the authors’; the rest is our summary.
- Cite
- Ito K (2020). Review of the health benefits of habitual consumption of miso soup: focus on the effects on sympathetic nerve activity, blood pressure, and heart rate. Environmental health and preventive medicine. doi:10.1186/s12199-020-00883-4Free full textPubMed 32867671DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error