There has been a fascination with acupuncture in the west since 1971 when Nixon and his enterouge took a trip to China. One of his political analyst, James Reston, had a bout of severe appendicitis and received post surgical pain relief with acupuncture. Upon his homecoming, Reston wrote an article that appeared in the NY times which may have in some way set the foundation for the Chinese Medical movement in the west as we know it today where you can find, usually somewhere close, one of the 28,000 certified acupuncturist (either by state regulation or the National Commision for acupuncturists) in all of the fifty two of the United States.
There are Eastern and Western theories as to why acupuncture is as effective as it is, and there are quite a few studies that have been done or are currently underway. Safe to say that acupuncture, when performed by a trained and licensed practitioner, is a safe and effective treatment for a myriad of diseases. The World Health Organization has a comprehensive list of what it has found acupuncture to be a "proven effective treatment."
The history of acupuncture dates back at least 4,000 years. In the tradition of Eastern medicine, acupuncture is described as a form of healing which causes the movement of Qi (energy) in channels called meridians. Qi is defined as a vital substance; the combination of the air we breath the food we eat and movement. Some describe it as an electromechanical force, some describe it as life's energy, others the essence of life. Acupuncture is the practice of inserting fine, hair like in diameter needles at specific points in the body to stimulate, disperse, and regulate the flow of qi, or vital energy, and restore a healthy energy balance.
Western practitioners view the acupuncture points as places to stimulate nerves, muscles and connective tissue. This stimulation appears to boost the activity of your body's natural painkillers and increase blood flow.
Neurohormonal Theory: Some studies suggest that the analgesic action of acupuncture is associated with the release of natural endorphins in the brain.
Recent studies showing micro fiber ducts in the blood and lymph vessels that seem to follow the path of meridians.
Other Western theories:
Meridian pathways have been observed objectively. When injecting radioactive dye into a meridian, the dye flows along the expected meridian pathway, which does not correspond to any other anatomical structure.
Electrical conductivity of acupoints is measurably different than that of surrounding tissue.
Brain imaging via PET and MRI has demonstrated that there is a correlation between acupuncture stimulation and the activation or suppression of corresponding regions of the brain cortex.