"Natural" doesn't necessarily mean better
If there's one fallacy that grips the brains of proponents of "natural healing," "holistic medicine," or, as the vast majority of it is, quackery, it's an appeal to nature. Basically, the idea that underlies the appeal to nature is a profane worship of nature as being, in essence, perfect, with anything humans do that is perceived as somehow being "unnatural" being viewed as, at the very least, inferior and at the very worst pure evil.
Source: scienceblogs.com