packisbak1,
As far as I know, except for garlic, nobody has tested the efficacy of any of these and then reported on the results. Lots of anecdotal information though, both pro and con. One garlic study I read showed that it killed freshwater ich in 24 hours at concentrations of 117 ppm to 570 ppm, but had no effect at 30 ppm - just to put things in perspective, they were talking on the order of 1 gram of garlic extract PER GALLON - I bet that smelled nice! It was in the North American Journal of Aquaculture 2003, volume 65 issue 1.
In my opinion, if a product does not list its active ingredients on the label it doesn't get used by me. I am wary of "natural cures" "herbal remedies" and "tonics".
Although I am not personally a big fan of hyposalinity treatments for ich, (I use copper) I would go that route before ever using a "natural" cure as the backbone of my quarantine protocol.
JHemdal