Ever since Westerners started using acupuncture to treat their aches and pains, a debate has raged as to whether the ancient Chinese medicine really did work.
Now scientists have discovered that deep-needle acupuncture can combat pain.
A study found that the technique can turn off parts of the brain involved in pain, which could explain how the practice may work as an anaesthetic.
Researchers found that an acupuncture technique using deep needling led to the deactivaton of part of the brain's limbic system, which helps the body to be conscious of pain.
Neuroscientists believe that the findings show that acupuncture has a measurable effect on the brain and that the study could provide a possible mechanism to explain how acupuncture can relieve pain.
The research was carried out on a set of volunteers by scientists at Hull York Medical School as part of a new BBC TV series called Alternative Medicine: The Evidence, to be broadcast on Tuesday evening on BBC2.
Professor Kathy Sykes of Bristol University, who will present the programme, said that the medical school's MRI brain scanners showed that certain forms of acupuncture have a deep and measurable effect on the brain.
"The particular area of the brain that MRI shows deactivation for during acupuncture is part of the pain matrix which is involved in the perception of pain," Professor Sykes said. "It helps someone decide whether something is painful or not. So it could be that acupuncture in some ways changes a person's pain threshold."
The study tested two forms of acupuncture on separate sets of volunteers. One involved inserting needles into the skin on the back of the hand by about a millimetre. The other inserted needles up to a centimetre into the same pressure points.
Brain scanning images of the group that underwent superficial needling show nerve activation in the motor cortex of the brain, the area that normally responds to touch or pain.
However, when the acupuncturist used the deeper needles, which were also rotated as part of an acupunctural effect called de chi, the scientists found a measurable deactivation in the brain's limbic system.
Mark Lythgoe, a neuroscientist at University College London who helped to oversee the study, said that the findings were significant because they demonstrated a physical effect on the brain. "This may account for the way it works. This is a possible novel neurobiological mechanism for the action of acupuncture," Dr Lythgoe said.
As part of the programme, Professor Sykes visited China, where she witnessed a conscious patient undergoing open-heart surgery with the help of acupuncture but without the use of general anaesthetics.
The people in the study who experienced deep-needle acupuncture said that they felt a tingling sensation but not pain. The scientists said they were used to seeing drugs or other medical treatments activating parts of the brain and they were surprised to see something that had the opposite effect.
"I'm just thrilled that we managed to do a real scientific experiment, shaped and run by scientists and acupuncturists together, where we found something quite unexpected - that acupuncture is having a measurable effect on the brain," Professor Sykes said.
The BBC series will also investigate other forms of alternative medicine, such as healing and herbalism.