How Acupuncture Works? By: Chris Kresser LA.c

In this post we’re going to explore how acupuncture works from a western scientific perspective. As I’ve argued in the previous articles, there is no disagreement between the fundamental anatomical and physiological concepts of western and Chinese medicine. However, as methods of scientific inquiry have progressed, the mechanisms of acupuncture are beginning to be more clearly understood. Acupuncture effects every major system of the body, including the cardiac, gastrointestinal, circulatory, cerebral, genitourinary, endocrine and immune systems. It would take an entire book to describe all of the mechanisms involved, and in fact there is such a book for those who are interested in that level of detail. In this post my purpose is to summarize that research in a way that’s easy for lay people to understand, while providing links to more technical resources for medical professionals and others that might be interested. Broadly speaking, acupuncture has three primary effects:  It relieves pain.

1. It reduces inflammation.
2. It restores homeostasis.

Homeostasis refers to the body’s ability to regulate its environment and maintain internal balance. All diseases involve a disturbance of homeostasis, and nearly all diseases involve some degree of pain and inflammation. In fact, research over the last several decades suggests that many serious conditions like heart disease previously thought to have other causes are in fact primarily caused by chronic inflammation. If we understand that most diseases are characterized by pain, inflammation and disturbance of homeostasis, we begin to understand why acupuncture can be effective for so many conditions.
Several modes of action have been identified for acupuncture, which I’ll discuss below. The mechanisms can get quite complex. But ultimately acupuncture is a remarkably simple technique that depends entirely upon one thing: the stimulation of the peripheral nervous system. It’s important to point out that when nerves supplying acupoints are cut or blocked there is no acupuncture effect.
A large body of evidence indicates that acupoints, or “superficial nodes” as they are more accurately translated, have abundant supply of nerves. According to Chen Shaozong, “For 95% of all points in the range of 1.0 cm around a point, there exist nerve trunks or rather large nerve branches.” 1
The following is a list of mechanisms that have been identified so far:

• Acupuncture promotes blood flow. This is significant because everything the body needs to heal is in the blood, including oxygen, nutrients we absorb from food, immune substances, hormones, analgesics (painkillers) and anti-inflammatories. Restoring proper blood flow is vital to promoting and maintaining health. For example if blood flow is diminished by as little as 3% in the breast area cancer may develop. Blood flow decreases as we age and can be impacted by trauma, injuries and certain diseases. Acupuncture has been shown to increase blood flow and vasodilation in several regions of the body.
• Acupuncture stimulates the body’s built-in healing mechanisms. Acupuncture creates “micro traumas” that stimulate the body’s ability to spontaneously heal injuries to the tissue through nervous, immune and endocrine system activation. As the body heals the micro traumas induced by acupuncture, it also heals any surrounding tissue damage left over from old injuries.
• Acupuncture releases natural painkillers. Inserting a needle sends a signal through the nervous system to the brain, where chemicals such as endorphins, norepinephrine and enkephalin are released. Some of these substances are 10-200 times more potent than morphine!
• Acupuncture reduces both the intensity and perception of chronic pain. It does this through a process called “descending control normalization”, which involves the serotonergic nervous system. 2 I will explain this process in further detail in the next post.
• Acupuncture relaxes shortened muscles. This in turn releases pressure on joint structures and nerves, and promotes blood flow.
• Acupuncture reduces stress. This is perhaps the most important systemic effect of acupuncture. Recent research suggests that acupuncture stimulates the release of oxytocin, a hormone and signaling substance that regulates the parasympathetic nervous system. You’ve probably heard of the “fight-or-flight” response that is governed by the sympathetic nervous system. The parasympathetic nervous system has been called the “rest-and-digest” or “calm-and-connect” system, and in many ways is the opposite of the sympathetic system. Recent research has implicated impaired parasympathetic function in a wide range of autoimmune diseases, including arthritis, lupus, rheumatoid arthritis and inflammatory bowel disease.

Several other mechanisms have been identified, but the ones I’ve listed above are the most relevant and clearly understood.
Some purists object to acupuncture being described in biomedical terms. They claim that such descriptions are “reductionistic” and narrow-minded, and don’t take into account those aspects of acupuncture that we may not yet understand.
Others who are still committed to the “energy meridian” model are opposed to the biomedical descriptions because, in their eyes, such scientific inquiry “takes the magic” out of acupuncture.
While I agree that there we don’t yet fully understand how acupuncture works, I think it’s vital that practitioners of acupuncture are able to explain what we do know about it from a biomedical perspective to their patients and colleagues in the medical profession. As practitioners we have a moral obligation to provide each patient with the latest medical understanding available in terms they can understand and relate to. Doing this will improve patient outcomes and open the door for acupuncture to be integrated into the healthcare system, which is needed now more than ever.
I would also suggest that explaining the mechanisms of acupuncture in scientific terms should not in any way lessen our appreciation of its uniqueness. The fact that inserting fine needles into the skin can have such a broad range of powerful effects is just as remarkable when those effects are explained in terms of the nervous system as when they are explained in terms of “energy” and “meridians”. When you consider that the Chinese made these discoveries hundreds of years before the birth of Christ, acupuncture is even more impressive.
What’s more, as others have pointed out, acupuncture is inherently holistic even without the “energy meridian” theory because it restores internal homeostasis through the simple act of piercing the skin with a needle.
In the next article I’ll explain the latest theory on how acupuncture relieves pain in more detail. Stay tuned, and as always, I welcome your comments!
 

1. Shaozong, C. Modern acupuncture theory and its clinical application. (Chapter 5 The Morphologic Relationship between Points and Nerves). International Journal of Clinical Acupuncture. 2001;121(2):149-158 
2. Dung HC. Anatomical features contributing to the formation of acupuncture points. American Journal of Acupuncture. 1984;12:139-143