Terrain Theory Revisited

I will outrage some of you. Others, perhaps the majority, will agree with what I write here. Some may simply scratch their heads and wonder what on earth I’m even talking about. What I’m talking about is terrain theory, the supposed challenge to germ theory, which is the basis of today’s understanding of infectious disease.

Essentially, terrain theory proposes that our physical health is largely influenced by how we take care of ourselves: how we eat, sleep, and exercise. It also assumes that exposure to toxins can influence disease processes. A body weakened by a poor environment becomes more susceptible to disease, while a strong body resists disease. For most people, this theory sounds quite reasonable, as it conforms with our own experience. We know that when we take care of ourselves, we get sick less often.

What has become controversial within the terrain theory community is the argument that germ theory, the observation that disease is caused by infectious agents (microbes, viruses, fungi, and parasites) is flat-out wrong. Many who ascribe to the terrain theory model of disease deny the existence of infectious disease entirely, arguing that it’s the body itself—weakened from poor self-care—that activates the disease process. No environmental organisms necessary.

I find that argument unconvincing.