New observational research out of Japan is highlighting the virtues of vinegar. Scientists from Osaka University report regular consumption of sunomono among older men (40+) correlates with lower blood pressure. Sunomono is a Japanese side dish prepared with rice vinegar and either sliced cucumber or seaweed.

Prior research tells us that people who drink 30 mL of vinegar on a daily basis tend to display lower blood pressure levels. However, studied individuals also lost notable weight, which may explain the aforementioned lower blood pressure.

“The benefits of vinegar in a healthy diet are well known. Our research is the first observational study of these benefits; we didn’t ask participants to change anything,” co-author Hiroaki Kanouchi explains in a statement.

Researchers say that studying sunomono provided a unique opportunity to perform an observational project assessing if vinegar consumption (within the context of an otherwise normal diet) correlates with blood pressure fluctuations. Sunomono is a very common food in Japan, typically eaten habitually by older generations. Locally, Japanese supermarkets offer a wide variety of individually prepackaged sunomono portions. In other words, sunomono is a big source of dietary vinegar among the Japanese.

To study this topic researchers recruited 1498 men and women over the age of 40 who had already been screened for hypertension or other disqualifying health issues. Among that larger group, 746 subjects had their blood pressure tested and categorized per the Japanese Society of Hypertension’s guidelines. Those same participants then completed a dietary survey that focused heavily on consumption of sour vinegary foods like sunomono.

“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. In sunomono, vinegar is part of the dish, people usually finish it,” Kanouchi explains.

As researchers assessed all of the collected data, a pattern started to emerge. “Men who did not habitually eat sunomono had significantly higher blood pressure, even though their weight and BMI were the same,” Professor Kanouchi notes. “We believe it could be promoting growth of good gut microbiota, but we would need more studies to confirm that.”

Consuming sunomono at least once per month was found to correlate with lower average blood pressure among male subjects. This held true even after study authors accounted for a multitude of other factors including BMI, age, smoking history, and sodium/potassium/alcohol consumption habits.

“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.

The study is published in Heliyon.