Sunomono may influence gut environment to lower BP in men, study suggests
The team believe the seaweed and vinegar that accompanies the side dish may be behind the health benefit, with the two ingredients likely responsible for an increase in short-chain fatty acid (SCFA)-producing bacteria.
“Men who did not habitually eat sunomono had significantly higher blood pressure, even though their weight and BMI were the same," explains Hiroaki Kanouchi, study author and Professor at Graduate School of Human Life and Ecology Division of Human Life and Ecology Professor at Osaka Metropolitan University.
"We believe it could be promoting growth of good gut microbiota, but we would need more studies to confirm that."
The team began a cross-sectional study that involved 746 individuals (257 men and 489 women) aged 40 years and over.
Nutrient intake was first estimated based on the self-administered diet history questionnaire that included the intake frequency of vinegar-based side dishes (Sunomono and pickles)
Blood pressure was categorised into four groups and the link between the intake of vinegar-based side dishes and blood pressure categories was also analysed.
The analysis was adjusted for age, body mass index, smoking history, excessive alcohol intake, energy intake, protein intake, sodium intake, potassium intake, and seaweed intake.
Results revealed approximately 13.6% men and 6.1% women had no Sunomono eating habits.
In men, eating Sunomono, but not pickles, was significantly related to the blood pressure categories.
However, more frequent consumption of Sunomono did not show an improvement in the blood pressure category.
The relationship between eating Sunomono and blood pressure categories was not recognised in women.
"Vinegar is hard to observe because it isn't a big ingredient in meals; you might get a little in vinaigrette or pickles, but people rarely drink the pickle's vinegar brine,” explains Professor Kanouchi. “In sunomono, vinegar is part of the dish, people usually finish it."
The findings point to consuming sunomono -- at least monthly – as linked to lower average blood pressure among men, even when adjusted for age, BMI, smoking history, and intake of sodium, potassium, and alcohol, amongst other factors.
Easy lifestyle change
"We are not sure how the vinegar causes these health benefits; increasing vinegar consumption doesn't lead to further improvement in blood pressure.
However, diet is one of the easiest things to change! I want everyone to know that even occasionally eating sunomono could make a difference in blood pressure," Professor Kanouchi concludes.
One suggestion put forward raises the one possibility of an improved intestinal environment as a result of seaweed and vinegar intake.
Human studies have shown that the diversity of gut microbiota is related to blood pressure
Gram-negative microbiota are highly abundant in the high blood pressure category, whereas short-chain fatty acid (SCFA)-producing bacteria are less abundant compared to that of normotensive patients.
Recently, one report demonstrated the effect of vinegar intake on gut microbiota using a rat model of hyperoxaluria.
They showed that the abundance of SCFA-producing bacteria was significantly increased by daily oral administration of two millilitres per kilogram (mL/kg) Shanxi-aged vinegar containing water for four weeks, but there was a concern regarding the extremely high vinegar dosage.
Published online: DOI: 10.1016/j.heliyon.2022.e09505
“Association of blood pressure and dietary intake of Sunomono, Japanese vinegared side dishes, in community-dwelling Japanese: A cross-sectional study.”
Authors: Hiroaki Kanouchi et al.