This is why I grew up to learn to only trust medical studies over anecdote. Even then it's good to be skeptical. Placebo can be incredibly powerful.
Any sources?
Firstly, The thing is about the placebo effect, is that it is an actual effect.
Placebos are tough to account for in studies specifically because they actually DO help, for something to have medicinal properties it needs to have a greater effect than a placebo. Placebos even have been known to work when people know they are placebos.
The second one is that humans are terrible at self diagnosis / analysis, we are way too emotionally influenced, too biased, and there are too many variables to make conclusions on treating yourself. That's where scientific studies do a good job of removing biases and variability from the equation.
I'm not saying banana peels definitely don't help, because I honestly don't have a bloody clue, but I would caution telling other people about it with such certainty until there is some well researched initial evidence behind it.
We all, by merit of commenting here and having access to the Internet, have these qualifications.
Sounds like it works and achieved the intended effect. This is why I grew past my "I only believe what the scientists tell me to" phase and decided to selectively trust medical studies, since it's my life and my anecdote, and I'll decide what does or does not work in my anecdote.
I was merely pointing out the persuasive power of placebo affect which has resulted in a billion dollar 'holistic' industry to treat medical conditions and my personal experience growing up with someone who believes that non-sense. Which gave me a strong bias towards scientific results over 'natural' ones.