Even worse, the placebo group drank peppermint cordial. The researchers are arguing there is no peppermint oil in it because it's not a listed ingredient, but the listed ingredients have "flavorings". Which, I'd be shocked if it weren't peppermint oil.

This is the "placebo" they used [1]

[1] https://www.tesco.com/shop/en-GB/products/254854798