The Cochrane Review reviewed 33 separate trials into acupuncture and its so-called "sham" counterpart. The latter also involves the insertion of needles - but not into traditional "energy points".
The scientist leading the review said the results showed that putting needles into particular locations might not be that important. Acupuncture is still regarded as a "complementary" therapy, but is increasingly being viewed as a potential mainstream treatment for certain conditions, such as chronic pain.
The endorsement by the Cochrane Collaboration is likely to lead to further calls for it to be made more widely available on the NHS.
The traditional explanation of its effects involves tapping into a network of "meridians" around the body to regulate the flow of an energy called "chi". Acupuncture points are located at various positions along these meridians.
However, many modern acupuncture specialists believe that the insertion of needles actually cause subtle changes in the nervous system and brain activity which can be beneficial - and place needles in other parts of the body rather than concentrating solely on traditional acupuncture points.
The Cochrane reviews involved a total of 6,736 patients, who were given acupuncture to prevent either mild to moderate "tension" headaches, or migraine attacks. Following a course of at least eight weeks, acupuncture patients suffered fewer headaches than those given only painkillers.