Acupuncture is actually a real type of medicine or medicinal theory that is based on actual anatomy and physiology. Concentrating on the improving the flow of Oxygen (Qi), Blood (Xue) and Nutrients (Ying Qi).
The impairment of blood flow or blood stagnation is the number 1 cause of disease. Which makes sense, if there is a problem with blood flow to any area of the body there will be impaired function.
The body cannot heal without blood flow to the affected area so this make sense, as acupuncture helps the body heal itself. Acupuncture does this by causing the blood vessels to dilate or constrict to either; increase or decrease blood flow to specific areas of the body. This is done to relieve pain and improve organ function.
It also works by stimulating the nervous system by activating nociceptor sensory nerves and proprioceptor fibers that travel from the skin, to the spine and to the brain. Acupuncture does this by improving nerve signals to your brain to realise opioids (natural painkillers) to shut off the pain signal eliminate the pain.