Just how acupuncture prevents disease is not based, it seems, on understanding it but on restoring proper flow through the meridians. Since meridians and the energy flow do not seem to exist physically, it is very easy to explain how the flow of energy can be restored to normal by placing needles in the skin. All one has to do is have faith and use one's imagination since there is nothing to see or measure. There are no studies, to my knowledge, that have demonstrated if acupuncture prevents disease, let alone shown how.
X-ray the spine to see if an asymptomatic individual has any misalignments.
In fact, spinal manipulation has not been shown in peer-reviewed studies to do anything more than reduce lower back pain. A recent study on chiropractic and asthma showed no improvement of asthma by spinal manipulation. If this technique is unable to treat diseases which, by their own theory should respond to manipulation, then it's hard to believe it will do anything to preserve long-term health, other than that of the chiropractor's bank account. In fact, homeopathy doesn't even appear to consider the causative processes of disease. The major focus is on substances that, in the right quantities, simulate the patient's symptoms.