How acupuncture reduces pain is not clear.
尚不清楚针灸疗法减轻疼痛的原理。
One theory explaining this phenomenon suggests that acupuncture blocks pain signals from reaching the brain.
有一种理论这样解释这一现象，针灸疗法阻止疼痛信号传递到大脑。
Another theory relates acupuncture to the production of chemicals in the body which reduce pain.
另一种理论提出，针灸疗法会促进体内减少疼痛的化学物质的产生。
A lot of people now subscribe to these theories.
现在许多人都赞同这些理论。
As a unique contribution of traditional Chinese medicine, acupuncture spread to many other Asian countries, such as Japan, as early as the 6th century.
由于中医的独特效果，针灸传播至许多其他亚洲国家，例如早在6世纪的时候传到日本。
It was introduced to the West in the 17th century.
17世纪，这一疗法传到了西方。
Today acupuncture has become popular round the world, as have other traditional Chinese medicines.
与其他传统中医一样，现在针灸在世界范围内流行开来。
The World Health Organization recommends acupuncture as a good treatment for over forty medical problems.
世界卫生组织推荐针灸为治疗四十多种医学问题的良方。
While doubts about its safety have faded away, interest continues to grow.
而有关其安全性的疑虑也消失了，反而对它的兴趣在持续增长。