According to traditional Chinese medical theory, acupuncture points are situated on meridians along which qi, the vital energy, flows. There is no known anatomical or histological basis for the existence of acupuncture points or meridians. Modern acupuncture texts present them as ideas that are useful in clinical practice. According to the NIH consensus statement on acupuncture, these traditional Chinese medical concepts "are difficult to reconcile with contemporary biomedical information but continue to play an important role in the evaluation of patients and the formulation of treatment in acupuncture.
The earliest written record that is available about acupuncture is Huangdi Neijing, which suggests acupuncture originated in China and would explain why it is most commonly associated with traditional Chinese medicine (TCM). Different types of acupuncture (Classical Chinese, Japanese, Tibetan, Vietnamese and Korean acupuncture) are practiced and taught throughout the world.
Acupuncture has been the subject of active scientific research since the late 20th century but it remains controversial among Western medical researchers and clinicians. Due to the invasive nature of acupuncture treatments, it is difficult to create studies that use proper scientific controls. Some scholarly reviews have concluded that the effectiveness of acupuncture as a treatment can be explained primarily through the placebo effect, while other studies have suggested some efficacy in the treatment of specific conditions. The World Health Organization published a review of controlled trials using acupuncture and concluded it was effective for the treatment of 28 conditions and there was evidence to suggest it may be effective for several dozen more. Additionally, the National Center for Complementary and Alternative Medicine (NCCAM) of the National Institutes of Health (NIH), the American Medical Association (AMA) and various government reports have studied and commented on the efficacy (or lack thereof) of acupuncture. There is general agreement that acupuncture is safe when administered by well-trained practitioners using sterile needles, and that further research is appropriate.