There are two contrasting theories as to why people get sick – germ theory and terrain theory.
Germ theory suggests that there is usually a specific cause for any disorder, for example a bacterial infection. The cause is bacteria. A physician thinking in this way would use anti-biotics as a first line of treatment. Whether it is bacteria or a fungus or a virus, the doctor diagnoses a specific agent as the cause and the treatment plan would be to deal with that agent.
Terrain theory on the other hand argues that it is the health of the body’s internal environment that is the fundamental cause of disease, and that pathogens such as bacteria or viruses are opportunists. In other words, the bacteria or viruses are symptoms not causes. A physician thinking in this way would be more likely to think of lifestyle or diet changes to improve health and enable the body to heal itself. A body in balance is able to fight off infection and, even if it is infected, is more able to deal with it without serious illness.
While germ theory and terrain theory are not directly related to acupuncture theory, they are useful ideas to bear in mind when talking about how acupuncture can work. If a patient goes to the doctor with mild low mood and anxiety for example, the problem could be framed as a deficiency of serotonin in the brain. Such a deficiency could be addressed by prescribing antidepressants. The cause of the low mood is a lack of a certain hormone.
This is not the way an acupuncturist would approach such a problem. The acupuncturist would try to figure out why the patient feels low. Low mood can be the symptom of many different imbalances in the body. By questioning and observing, feeling the pulse and looking at the tongue the acupuncturist seeks to work out what is going on. It could be that the problem starts in the gut and with difficult digestion, leading to fatigue and lack of sleep. This is quite commonly the case. There is more and more evidence in western medical research showing that there is an intimate link between our gut health and our mood. Acupuncture in this case would be working to improve the patient’s digestion to fundamentally improve general well-being. The cause of the low mood may indeed be the lack of serotonin in the brain but instead of prescribing a pill, acupuncture supports the body’s resources so that it can function naturally and produce its own hormones appropriately.
This approach is useful for cases when western allopathic medicine fails to prevent a chronic condition from recurring and necessitating the use of harsh drugs over extended periods. In these cases, improving the body’s “terrain” can be very beneficial. I would add a caveat here. If you have sepsis for example, you need immediate strong anti-biotic medication. If you have a serious mental health condition, you need specialist medical help. I always tell my patients that if they get hit by a bus, they do not need to call an acupuncturist!