A large proportion of the benefit from any treatment, whether it is medical care or complementary and alternative care like chiropractic, comes from the so-called "placebo effect".  This effect seems to come from the body's increased ability to heal itself when the mind and beliefs becomes involved.  It also means that a lot of treatments may actually be less effective than you thought, even drugs and surgery...read more here .  (This pdf first appeared in "The Star" in Sept 2008).