David Gorski in Science-Based Medicine:
There are many fallacies that undergird alternative medicine, which evolved into “complementary and alternative medicine” (CAM), and for which the preferred term among its advocates is now “integrative medicine,” meant to imply the “best of both worlds.” If I had to pick one fallacy that rules above all among proponents of CAM/IM, it would have to be either the naturalistic fallacy (i.e., that if it’s natural—whatever that means—it must be better) or the fallacy of antiquity (i.e., that if it’s really old, it must be better). Of course, the two fallacies are not unrelated. In the minds of CAM proponents, old is more likely to have been based on nature, and the naturalistic fallacy often correlates with the fallacy of antiquity. Basically, it’s a rejection of modernity, and from it flow the interest in herbalism, various religious practices rebranded as treatments (thousands of years ago, medicine was religion and religion was medicine—the two were more or less one and physicians were often priests as well), and the all-consuming fear of “toxins,” in which it is thought that the products of modernity are poisoning us.
Yes, there is a definite belief underlying much of CAM that technology and pharmaceuticals are automatically bad and that “natural” must be better. Flowing from that belief is the belief that people were happier and much healthier in the preindustrial, preagricultural past, that cardiovascular disease was rare or nonexistent, and that cancer was seldom heard of. Of course, it’s hard not to note that cancer and heart disease are primarily diseases of aging, and life expectancy was so much lower back in the day that a much smaller percentage of the population lived to advanced ages than is the case today. Even so, an implicit assumption among many CAM advocates is that cardiovascular disease is largely a disease of modern lifestyle and diet and that, if modern humans could somehow mimic preindustrial or, according to some, even preagricultural, lifestyles, that cardiovascular disease could be avoided.