It has been a stunning triumph of marketing and propaganda that many people believe that treatments that are “natural” are somehow magically safe and effective (an error in logic known as the naturalistic fallacy). There is now widespread belief that herbal remedies are not drugs or chemicals because they are natural. The allies in Congress of those who sell such products have even passed laws that embody this fallacy – taking herbal remedies away from FDA oversight and regulating them more like food than drugs.
The other major fallacy spread by the “natural remedy” industry is that if a product has been used for a long time (hundreds or thousands of years), then it must also be safe and effective because it has stood the test of time (this fallacy is referred to as the argument from antiquity). This fallacy even has a specific regulatory term to invoke it – GRAS or “generally recognized as safe.” With food and food ingredients the FDA does not require evidence of safety if the ingredient is generally recognized as safe. This might make sense when referring to foods that have be eaten by humans for a long time. Although the logic is still dubious, it’s just practical – the FDA could not take upon itself the task of proving that every food eaten by humans has no significant negative health consequences. It is more a recognition of practicality than reality.