Where does this idea come from that "natural" stuff is always good for you? Poison nightshade is "natural." Most drugs are "natural" in a way (penicillin, cephalosporins, aspirin, etc. all originally come from nature.) And even natural stuff that is <i>benign</i> can have unforeseen consequences when combined with other, powerful drugs (as an example, grapefruit juice interferes with anti-rejection drugs and is thus gravely dangerous post-transplant).
That's even ignoring the hazards of low quality control, non-standardized dosing, contamination with other substances, and likely ineffectiveness that you get with things the FDA doesn't regulate or test (like herbs). They should be used with <i>extreme</i> caution; in low enough doses that they're truly harmless, they likely won't have any major physiological effect at all (i.e., 5 milligrams of Ibuprofen isn't gonna make you sick--won't do a damn about your headache either). And if they have a physiological effect, after all, that means they're messing with your system, somehow (which may or may not be harmless).
Meanwhile, their advocates, often coming from the herb or herb-based cure books business, can be as big cronies as those of mainstream pharmaceuticals, and are not as strictly regulated. Food for thought. <i>"Just because the establishment is out to get you, doesn't mean its detractors aren't."</i>