Peppermint group N=20. Mkay. 2 of those lost to followup, one because they didn't like the taste (control group got peppermint cordial). The result might be real but needs followup before we all starting gulping down peppermint oil.
pretty tiny amount of peppermint was consumed
FWIW, I had an Indian co-worker who took peppermint oil frequently and said that it was very good for his upset stomach.
How could they be? The peppermint cordial almost certainly contains peppermint oil!
The authors chose it because it wasn't explicitly listed on the ingredients list, but what was listed was "flavorings". I highly doubt coca cola used anything other than peppermint oil to flavor a peppermint drink. That would be bizarre to say the least.