I tend to be suspicious about various and sundry advertised on TV that will :cure what ails ya". The placebo effect is so significant I really suspect most of these things are just that, but maybe some have a therapeutic effect.
I tried melatonin because my wife said it works great, and some others said the same, and could discern zero effect, but that is highly qualitative of course. I've seen some recent stuff suggesting it could be bad for us.
One thing I know is that the stomach is a chemical factory and a lot of stuff we eat doesn't survive intact after pH 1.5 sloshing about with a lot of enzymatic activity.