Dietary supplements often are taken for their drug-like effects, but, unlike drugs, they are subject to very little federal regulation because they are (supposed to be) made solely from "natural" substances. So, with that in mind, read this article by Alison Young. Here's an excerpt:
For the second time in recent weeks, scientists have found a "non-natural" amphetamine-like compound in dietary supplements – yet federal regulators have issued no warnings to consumers about the ingredient. Tests of 21 supposedly all-natural supplements by U.S. Food and Drug Administration scientists found nine products that contain the compound, according to their findings published in the Journal of Pharmaceutical and Biomedical Analysis.