Test Tube Study
An in vitro study is a trial that tests a substance in a test tube. Such studies are really only spurs for further research, as they don't prove that a treatment is effective in real life. An herb or supplement taken by mouth must be absorbed into the bloodstream, survive processing by the liver, and still manage to be effective when diluted by the fluids of the body. It's a long leap from a test tube result to a treatment that actually works.