COPD supplements

I have seen more than dozens of supplements that claim to be helpful with breathing with COPD. Of these dozens, I've researched each and every one and most, if not all, are a scam. How disheartening. Does anyone know of a supplement that is helpful for COPD and doesn't claim to "cure it in 2-3 days". I'm sure there are more people than myself that would like to know if there is something out there that is helpful without worrying if it would make the problem worse, or heaven forbid, create a different problem.