Sceptics have long said acupuncture is all in the mind. But a study has found that the ancient Chinese practice is as effective as popular painkillers for treating disabling conditions such as arthritis.
A team of scientists from two British universities carried out brain scans on patients while they underwent the 2500-year-old treatment.
The scans showed differences in the brain’s response to acupuncture needles compared with tests using "dummy needles" that did not puncture the skin.
Doctors found that the part of the brain that manages pain and the nervous system responded to acupuncture needles and improved pain relief as much as 15 per cent.
Dr George Lewith, from the University of Southampton’s Complementary Medicine Research Unit, said the improvement might seem modest, "but it’s exactly the same size of effect you would get from real Prozac versus a placebo or real painkillers for chronic pain".
"The evidence we now have is that acupuncture works very well on pain."
The findings, published in the scientific journal NeuroImage, have been welcomed by acupuncturists, who have long faced scepticism from scientists.
Persis Tamboly, of the British Acupuncture Council, said: "We’re really thrilled about this research. There will be critics of this subject until our dying days, but research like this substantiates what we’ve always maintained - that acupuncture works."
The council hopes the findings will help to make acupuncture become accepted as a National Health Service treatment.
Despite its controversial status, more than two million acupuncture treatments are performed each year. Celebrity supporters include Cherie Blair, Kate Winslet and Joan Collins.
The 14 patients in the study were put through three tests in random order, while "brain maps" were created using sophisticated positron emission tomography, or PET, scans at University College London.
In one test, researchers used blunt needles that pricked the skin, but which the brain registered as the sensation of touch. Dummy needles, where the tip was pushed back once it touched the skin, were then used, and in the third test the patients underwent acupuncture treatment with real needles.
The acupuncture needles had two measurable effects on the patients’ brains: as with the dummy needles, the brain released natural opiates in response to the expected effect of the needles.
But the scans showed that the real needles had an extra effect and stimulated another part of the brain called the ipsilateral insular. This improved pain relief 10-15 per cent - similar to the effect of taking conventional analgesic drugs.
The study, though, does not explain how acupuncture treats other problems such as stress or disease.
Dr Lewith said: "Further research is definitely planned. I have been involved in acupuncture research for 25 years, and I’m now getting a very realistic understanding of the effects of this mechanism."