The Arizona State University team behind this new research had previously studied whether drinking red wine vinegar could promote blood sugar balance. After coming up with promising results, they wondered if vinegar could also play a role in mental health given the gut-brain connection.
To dive into this previously unexplored topic area, they gathered 25 healthy college student volunteers during the peak of the pandemic last winter. Over the course of a four-week, placebo-controlled trial, about half of the students drank a liquid apple cider vinegar beverage (2 tablespoons vinegar diluted in 1 cup of water) twice daily with meals. The other half consumed a low-dose vinegar pill once daily. This pill did not have enough acetic acid–the main active ingredient in vinegar–to be considered to elicit a health effect. However, it was described as a vinegar pill and had the stench to prove it, so the control group that received it thought they were getting the real deal, making this a placebo-controlled, blinded study.
Over the course of the four weeks, the students’ diet and exercise routines remained the same. They were all instructed to complete validated questionnaires about their mood before the study started and after it wrapped up. They also provided urine samples for testing before and after the study.